CODE OF 1
P RACTICE
Repair And Overhaul
Ex Electrical Apparatus
Publication No: 300
Revi sion 1
December 1991
BEAMNAEMT
CODE OF PRACflCE
FOR THE
REPAIR AND OVERHAUL OF ELECTRICAL
APPARATUS FOR USE IN POTENTIALLY
EXPLOSIVE ATMOSPHERES
(other than Mining Applications or
Explosive Processing and
Manufacture)
T hi s Code has been prepared by the BEAMA
Committee for Electrical Equipment in Flammable
Atmospheres (CEEFA) a nd the Association of
Electrical and Mechanical Trades (AEMT) with the
participation of User Organisations.
The HSE have also been consulted and participated
in the preparation of this Code.
The Department of Energy considers repairs or
overhauls which meet the provisions of this Code
will be appropriate for offshore installations on
the United IGngdom Continental Shelf.
This code of practice takes the form of recommendations.
Whilst it is
intended to cover the majority of situations which will be met in practice it
is not possible for the code to cover every contingency. The reader should
therefore bear in mind that specific situations may call for add itional
precautions which are not specified in thjs code.
In particular, compliance
with the code does not necessarily confer immunity from any statutory or legal
requirement. In case of doubt about any particular apparatus or procedure the
reader should refer to the original manufacturer, user or certifying authority
in order to satisfy himself as to the steps which need to be taken to deal with
the particular circumstances facing him.
This publkation shall not be reproduced or repeated, in whole or in part, nor
stored in any informat ion storage or retrieval system without the previous
written consent of both BEAMA Limited and AEMT Limited.
Published jointly by BEAMA Limited and AEMT Limited
© 1984
BEAMA/AEMT
Reprinted January 1994 (editorial revision).
Reprinted August 1998
Price: £35 (Overseas £40)
Printed in England:
ISBN 0 9509409 1 7 (AEMT)
ISBN 0 90 1639 12 5 (BEAMA)
The main parts of the code of practice are:-
PART ONE
PARTTWO PART THREEPART FOUR PARTFIVE PART SIX
PARTSEVENPARTElGHT-
GENERAL REQUIREMENTS
TYPE OF PROTECTION 'd' (FLAMEPROOF)
TYPE OF PROTECfiON 'i' (INTRINSIC SAFETY)
TYPE OF PROTECTION 'p' (PRESSURIZED)
TYPE OF PROTECTION 'e' (INCREASED SAFETY)
TYPE OF PROTECTION 'N' or 'n' (NON-SPARKING)
TYPE OF PROTECTION's' (SPEClAL PROTECTION)
PR0TECJ10N BY ENCLOSURE FOR USE IN THE
PRESENCE OF COMBUSTIBLE DUSTS
CONTENTS:
Page
Foreword
IV
PART ONE -GENERAL REQUIREMENTS
Introduction
Section One - General
Section Two - Guidance for the Manufacturer
Section Three - Guidance for the User
Section Four- Guidance for the Repairer
1-1
1-2
1-7
1-7
1-8
Appendix 1 -Identification of Repaired Apparatus
PART TWO- TYPE OF PROTECTION 'd' (FLAMEPROOF)
2-1
2-1
2-1
Introduction
Section One -General
Section Two - Repair and Overhaul
Section Three - Reclamation
Section Four- Modifications
2-6
2-7
PART THREE- TYPE OF PROTECTION 'i' (INTRINSIC SAFETY)
3-1
3-1
3-1
Introduction
Section One -General
Section Two -Repair and Overhaul
Section Three -Reclamation
Section Four- Modifications
3-4
3-4
11
PART FOUR -TYPE OF PROTECTION 'p' (PRESSURIZED)
Introduction
Section One - General
Section Two -Repair and Overhaul
Section Three -Reclamation
Section Four -Modifications
Page
4-1
4-1
4-1
4-5
4-6
PART FIVE- TYPE OF PROTECfiON 'e' (INCREASED SAFETY)
5-1
5-1
5-1
5-6
5-7
Introduction
Section One - General
Section Two -Repair and Overhaul
Section Three- Reclamation
Section Four - Modifications
PART SIX- TYPE OF PROTECTION 'N' or 'n' (NON-SPARKING)
6-1
Introduction
Section One - General
Section Two - Repair and Overhaul
Section Three -Reclamation
Section Four- Modifications
6-1
6-1
6-5
6-7
PART SEVEN -TYPE OF PROTECfiON 's' (SPECIAL PROTECTION)
7-1
Introduction
Section One - General
Section Two -Repair and Overhaul
Section Three - Reclamation
Section Four -Modifications
7-1
7-1
1-3
7-4
PART EIGHT- PROTECTION BY ENCLOSURE FOR USE
IN THE PRESENCE OF COMBUSTIBLE DUSTS
Introduction
Section One - General
Section Two -Repair and Overhaul
Section Three- Reclamation
Section Four -Modifications
8-1
8-1
8-1
8-5
8-6
w
FOREWORD
Since 1970 there have been sweeping changes in the field of electrical
equipment for potentially explosive atmospheres with the introduction,
internationally, of developments in explosion protection concepts, construction
and test specifications, codes of practice and safety legislation.
Over the same period there have been corresponding increases in the production
and use of potentially explosive substances in manufacturing and finishing
processes which have widened the application of explosion protected apparatus
far beyond the traditional sector represented by the oil refining and
distribution industry.
Many more manufacturers, users, installers and repairers are now involvedt some
for the first time, in this specialized technical field which is more
constrained by detailed Standards, codes of practice, application and
legislation than other sections ofthe electrical industry.
The construction and test Standards are framed to facilitate apparatus having
acceptable levels and margins of safety. Overall level of safety depends also
upon the strict observance of codes of practice.
This code recommends
procedures and practices to be followed in connection with repairs and
overhauls.
lV
PART ONE- GENERAL REQUIREMENTS
0.
INTRODUCTION
This code is divided into separate parts, each concerned with an
individual type of protection.
In those cases where an apparatus
incorporates more than one type of protection, reference should be made
to the parts involved.
The reader should, however, note that this
code excludes types of protection 'o' - oil filling, 'q' - sand filling
or quartz filling etc. and also type 'm' which is generally
considered to be irreparable.
The objective of this code, as well as giving guidance on the practical
means of maintaining the electrical safety and performance requirements
of repaired apparatus, also recommends procedure:s for maintaining after
repair compliance of the apparatus with the provisions of the
Certificate of Assurance or Conformity or with the provisions of the
appropriate explosion protected Standard where a certificate is not
available.*
The nature of the explosion protection offered by each type of
protection varies according to its unique features:.
For example, the
nature of explosion protection afforded by Type of Protection 'd' is
essentially mechanical, whereas that afforded by Type of Protection 'i'
is essentially electrical.
Reference should! be made to the
appropdate Standard(s) for details.
·
Users are recommended to utilise the most appropriate repair facilities
for any particular item of equipment, whether they be the facilities of
the manufacturer or a suitably competent and equipped repairer.**
The code recognises the necessity of a required level of competence for
the repair of apparatus. Some manufacturers may recommend that the
apparatus be repaired only by them.
In the case of the repair or overhaul of apparatu1s which has been the
subject of third party certification, such as by BASEEFA, it may be
necessary to clarify the position of the continued conformity of the
apparatus with the certificate.
* NOTE:
While most apparatus of this kind is certified by a recognised
third party test house, such as BASEEFA, some apparatus may be
self-certified by manufacturers or other bodies and may not attract
a Certificate of Assurance or Conformity.
** NOTE: Whilst some manufacturers recommend that certain equipment be
returned to them for repair and some nominate repairers, there are
also competent independent repair organisations who have the
facilities to carry out this class of work.
1-1
Assuming that repairs and overhauls are carried out using good
engineering practices then:1.
If manufacturers' specified parts or parts as specified in the
certification documentation are used in a repair or overhaul then
the a pparatus should remain in conformity with the certificate.
2.
If repairs or modifications are carried out on apparatus
specifically as detailed in the certification documents then the
apparatus should still conform with the certificate.
3.
If repair or overhaul is carried out on apparatus in accordance
with this code of ·practice and the re levant Standard(s), although
not in compliance with 1 & 2 above, then it is unlikely that the
apparatus wi11 be unsafe although it may not conform fully with
the certificate.
4.
If other repair or modification techniques are used then it wiLl
be necessary to ascertain, from the manufacturers, and/or the
certification authority, the suitability of the apparatus for
continued use in a potentiaJly explosive atmosphere.
SECTION ONE- GENERAL
1.
Scope
This code of practice
(i)
gives guidance, principally of a
technical nature, on the repair and overhaul of certified apparatus
designed for use in potentially explosive atmospheres (other than
mining applications or explosive processing and manufacture).
(ii)
does not cover maintenance, other
than when repair and overhaul cannot be disassociated from maintenance,
neither does it give advice on cable entry systems which may require
renewa1 when the apparatus is re-installed. Recommendations regarding
routine maintenance, and the selection and installation of electrical
apparatus for use in potentially explosive atmospheres may be found in
BS 5345 and BS 6467 Pt 2.
(iii)
practices are adopted throughout.
assumes that good engineering
This Part of the code of practice
(i)
covers those aspects of repair
and overhaul which are common to all explosion protected apparatus and
subsequent sections provide guidance relevant to specific types of
protection.
(ii)
also identifies certain specific
responsibilities under the Health and Safety at Work etc. Act 1974 as
applicable to those who are likely to be concerned with the repair of
certified apparatus.
1-2
NOTE
Much of the content of this code is concerned with the re pair and
overhaul of electrical rotating machines.
This is not because they
are the most important items of expJosion protected equipment; rather
because they are often major items of repairable capital equipment in
which, whatever type of protection is involved, sufficient commonality
of construction exists as to make possible more detailed guidelines for
their repair and overhauL
2.
References
Standards and other publications relevant to thjs code are listed in
AnnexA.
3.
D efinition and Explanation of Terms
3.1
Serviceable Condition
A condition which permits a replacement or reclaimed component part to
be used without prejudice to the performance or explosion protection
aspects of the apparatus, with due regard to the certification
requirements as applicable, in which such a component part is used.
3.2
Repair*
An action to restore a faulty apparatus to its fully serviceable
condition and in compliance with the relevant Standard.
3.3
Overhaul*
An action to restore to fully serviceable condition an apparatus which
bas been in use or in storage for a period of time but which is not
.Q.ecessarily faulty.
3.4
Maintenance
Routine actions taken in accordance with the recommendations of Section
Four of BS 5345 Part 1, to preserve the fully serviceable condition of
the installed apparatus.
3.5
Component Part
An indivisible item from an assembly of such parts which form an
apparatus.
* NOTE:
The term "repair" a nd/or "overhaul" employed in this code are/is
equated with the term "refurbishing.. used in Guidance Notes GS8,
relating to the H ealth and Safety at Work etc. Act 1974.
1-3
3.6
Reclamation
A means of repair involving, for example, the removal or addition of
material to reclaim component parts which have sustained damage., in
order to restore such parts to a fully serviceable condition in
accordance with the relevant Standard.
3.7
Modification
A change, to the design of the apparatus which may affect
fit, form or function.
3.8
material~
Manufacturer
The maker of the apparatus (who may also be the supplier, the importer
or the agent) in whose name usually the certification (where
appropriate) of the apparatus was originally registered.
3.9
User
The user of the apparatus.
3.10
Repairer
The repairer of the apparatus - who may be the manufacturer, the user
or a third party (repair agency).
3.11
Certification
In the context of this Code, certification, leading to the issue of a
Cer.tificate of Assurance or a Certificate of Conformity, refers
primarily to assessments of apparatus carried out by any one of the
test houses** notified to the European Communities Commission under
ArticJe 14 of the Framework EEC Directive 76/117/EEC, as publis'hed in
the Official Journal of the European Communities No. L 24/25.
This Code may a_lso apply to apparatus certified by other recognised
certification authorities, or to apparatus which has been
self-certified by manufacturers or users as complying with recognised
Standards.
**NOTE:
BASEEFA (British Approvals Service for Electrical Equipment in
Flammable Atmospheres) and SIRA Test and Certification Ltd are
now the British National Testing and Certification Authorities
recognised as the test houses nominated to the European Commission
under the European Directives concerned with apparatus for use in
potentially explosive atmospheres in surface industries.
1-4
3.12
Certificate References
A certificate reference number may refer to a single design or a range
of apparatus of similar design.
The suffix ''B" or "X" to the reference number indicates special
conditions of use and the certification documents need to be studied
before such apparatus is installed, repaired or overhauled.
An 'S' suffix indicates that the apparatus is intended for use rn a
safe area only, but it may form part of a certified system. The 'S'
suffix has been superseded by [EExia] for new equipment.
3.13
Marking
Explanatory information on the marking of apparatus can be found in
BASEEFAEx-Memo No.1.
It may be necessary to remove or supplement the label in certain
circumstances as follows -
3.14
i)
if after repair or overhaul an apparatus is
changed such that it no longer conforms with
either the Stand~d or certificate, the
certification label should be removed but the
rating and other details should be preserved.
ii)
if the ·apparatus is changed during repair or
overhaul so that it still complies with the
Standard but does not necessarily comply with
the certificate, the certification label should
be supplemented by the addition of marking
referred lo in Part 1 Section 4 Clause 5
(p 1-9).
Copy Winding
Copy Winding is defined as that process by which a winding is totally
or partially replaced by another, the characteristics and properties of
which are comparable with the original.
•
4.
Statutory Requirements
The folJowing references on certain specific requirements of the Health
and ·Safety at Work etc. Act 1974 are for guidance only and the reader's
attention is drawn to the complete requirements of the Act and relevant
regulations made from time to time under the Act.
4.1
Manufacturer
The manufacturer's responsibj}jties under the Health and Safety at Work
etc. Act 1974 are stated in Section 6 of the Act, in particular:
1-5
"Clause 6 (1) (c)
to take such steps as are necessary to secure that there will
be available in connection with the use of the article at
work adequate information* about the use for which it is
designed and has been tested, and about any conditions
necessary to ensur~~ that, when put to that use, it will be
safe and without risks to health."
For further
clarification reference should be made to the Guidance Notes
on the Health & Sa£ety at Work etc. Act 1974, GS8.
*NOTE: Adequate Information
It is not reasonably practical to assume that adequate information is
or can be so widely d 1rculated that it is always available where and
when it is needed.
Sources of adequate information are users,
manufacturers or certifying authorities.
4.2
User
Apart from the need to comply with Section 2 of the HeaJth and Safety
at Work etc. Act 1974 (regarding safe installation and maintenance
duties of the employer), the user is also required to pay due regard to
Section 6 of the Act should he wish to undertake the repair or overhaul
of the equipment himself. However, the user should also be aware of
the following Guidance Note GS8 issued by the Health and Safety
Executive.
"61.
When an article is sent for refurbishing and the
ownership passes 1to the refurbisher, then so do the duties
under Section 6."
The user should also have regard to the following:
The Electricity at Work Regulations 1989 and HSE Memorandum of Guidance
on tbeEWR.
4.3
Repairer
The repairer's responsibility is covered by the following extract from
the Guidance Note GS8 issued by the Health and Safety Executive.
"61. .... If, however, it is sent for repair or modification
and the ownership does not pass to the repairer or modifier,
then it would appear that neither do the duties under
Section 6.
But where the repairer or modifier is involved
in the erection or installation of such an article on any
premises when it iis to be used by persons at work, then he
may have duties lander subsection 6(3).
However, in the
event of an accident occurring, e.g. as the result of the
negligence of the 1repairer or modifier, be may be held liable
under Section 36 of the Act."
1-6
SECTION TWO - GUIDANCE FOR THE MANUFACTURER
1.
Documents
In addition to the certificate, other documents, e.g. the appropriate
drawings, specifications, etc., suitable for the repair and/or
overhaul, should be available.
1.1
Repair and Overhaul Data
The data available for the repair and/or overhaul should generally
include, but need not be limited to, details of:
-
technical specification
performance and conditions of use
dismantUng and assembly instructions
certification limitations, where specified
marking (including certification marking)
recommended methods of repair/overhaul for the apparatus
The information may be subject to manufacturers' amendments including
those relative to certification.
1.2
Spare Parts
A list of spare parts should be included with the repair and/or
overhaul data which should identify those parts that particularly
affect the means by which the apparatus complies with the appropriate
Standard or certificate.
SECTION THREE- GUIDANCE FOR THE USER
1.
Certificates and Documents
The certificate and other related documents should be obtained as part
of the original purchase contract.
2.
Records and Work Instructions
It will be in the interest of the user that the repairer is notified,
wherever possible, of the fault and/or nature of the work to be done.
Records of any previous repairs, overhauls or modifications should be
kept by the user and made available to the repairer.
The user
should inform the repairer, for safety and health reason s, as to the
nature. of any harmful contaminating dust to which the apparatus sent
for repair has been exposed so that appropriate precautions may be
taken before work commences.
Special requirements stipulated in users' specifications, and which are
supplementary to the various Standards, should be brought to the
attention of the repairer.
3.
Re-instailation of Repaired Apparatus
Before repaired apparatus is re-commissioned, cable entry systems
should be checked to ensure they are undamaged and are appropriate to
the apparatus type of protection.
Recommendations may be found in BS 5345.
1-7
SECTION FOUR- GUIDANCE FOR THE REPAIRER
1.
Certification and Standards
The repairer's attention is directed to the need to be informed of, and
to comply with the rel~vant explosion protected Standards and
certification requirements applicable to the apparatus to be repaired
or overhauled.
Ll
Tiaining
The repairer of the apparatus should ensure that those concerned with
the repair and/or overhaul of the certified apparatus are trained and
supervised on this type of work.
Such training should cover:
i)
General principles of types of protection and
marking
ii)
Those aspects of equipment design which affect
the protection concept
iii)
Certification and Standards
iv)
The identification of replacement parts or
components authorized by the manufacturer
v)
The particular techniques to be employed in
repairs referred to in other parts of this code.
Appropriate refresher training should be given from time to time.
2.
Testing
Should it prove impracticable to carry out certain tests, e.g. a
component of a complete apparatus taken off site for repair, such as a
rotor of a rotating machine, it would be necessatry before putting the
repaired equipment back into service to ascertain from the user or
manufacturer the consequences of omitting such tests.
Attention is drawn to Section 40 of the Health amd Safety at Work etc.
Act 1974 which states:-
1-8
"In any proceedings for an offence under any of the rel~ant
statutory provisions consisting of a failure to cqmply with a
duty or requirement to do something so far as is practicable
or so far as is reasonably practicable, or to use the best
practicable means to do something, it shall be for the
accused to prove (as the case may be) that it was not
practicable or not reasonably practicable to clio more than was
in fact done to satisfy the duty or requiirement, or that
there was no better practicable means than was in fact used
to satisfy the duty or requirement."
3.
Documentation
The repairer should seek to obtain all necessary information/d~ta from
the manufacturer or user for the repair and/or overhaul of the
apparatus. This may include information relating to previous repairs,
overhauls or modifications. He should also have availaQ.le, and refer
to, the relevant explosion protected Standard.
The repairer should
ensure that the user receives copies of records of all work carried out
on the apparatus.
4.
Spare Parts
It is preferable to obtain new parts from the manufacturer, and the
repairer should ensure that only appropriate spare parts are used :in
the repair or overhaul of certified apparatus.
Depending on the
nature of the apparatus, those spare parts may be identified by the
manufacturer, the apparatus Standard or the relevant certification
documentation.
4.1
Sealed Parts
Parts which are required by the apparatus. specification and certificate
documents to be sealed may be replaced only by the particular spare
part(s) detailed in the parts list.
Note:
5
Devices incorporated in an apparatus to indicate interference
by third parties (e.g. security seals) as distinct from those
required in the certification documents, are not intended to
fa] I within the scope of this sub-clause.
Sparking
Any evidence of unusual sparking identified by t:he repairer should be
referred to the manufacturer.
To avoid the incidence of incendive sparking, the only precautions wbieh
can be taken at present relate to bonding.
Any bonding arrangements should be replaced andl positioned to at least
the provisiqns of the original specifi~tion.
1-9
On dismantling rotating machines, if inspection of the rotor indicates
signs of sparking, this should be referred to the manufacturer for
advice.
At present, it is not possible to deal with corona discharges should
they occur.
6.
Identification of Repaired Apparatus
Apparatus should be marked to identify tbe repair or overhaul and the
repairer's identity.
The preferred marking for repaired apparatus is
given in Appendix I (Page,l-14).
Records should also be maintained giving full details of the repair work
carried out.
7.
Quality Assurance
Adequate quality control and quaJity assurance procedures should be
followed.
NOTE:
In this context, 'adequate' denotes that the procedures should be
documented and supervised by staff who have been trained in such QA and
QC procedures. Guidance may be obtained from BS 5750.
8.
Reclamations
8.1
Exceptions
This clause is only concerned with reclamations which affect explosion
protection.
Where explosion protection is not affected, reclamation should be
affected by good engineering practice.
8.2
Exclusions
Some component parts are considered not to be reclaimable and are
therefore excluded from the scope of this document:
e.g.
i)
Component parts made from the following
materials glass, plastics, or any material
that is not dimensionally stable
ii)
Fasteners
iii)
Component parts, e.g. some encapsulated
assemblies, which have been stated by the
manufacturer not to be subjected to .rep~ir.
1-10
8.3
Requirements
Any reclamation should be carried out by trained personnel~ skilled in
the process to be employed1 using good engineering practices.
If any proprietary process is used, the instructions of the originator
of such a process should be followed.
All reclamations should be properly documented and records retained.
Such records should include -
i)
Identification of the component part
ii)
Method of reclamation
iii)
Detrul of any dimensions which diffe r from those
in relevant certification documents or the
original dimensions of the component part.
iv)
Date
v)
Name of the orgi'misation carrying out the
reclamation
If the reclamation is carried out other than by the user, the user
should be provided with a copy of the record.
A reclamation procedure which would result in dimensions affecting
explosion protection integrity being different from those given in
relevant certification documents may be permissible if such changed
dimensions still meet the stipulations of the relevant explosion
protection Standard.
1n the event of any uncertainty regarding the permissibility, from an
explosion protection safety point of view, of an intended reclamation
procedure, the advice of the manufacturer or certifying authority
should be sought.
It may also be necessary to carry out tests to
verify that the reclamation procedure is acceptable.
8.4
RecJamation Procedures
The following outlines some of the reclamation procedures which MAY be
applicable to explosion protected apparatus.
IT SHOULD BE RECOGNISED THAT NOT ALL PROCEDURES ARE
APPLICABlE TO AlL MEIHODS OF PROTECITON. DETAILED
ADVICE IS GIVEN IN TilE APPROPRIATE PARTS OF THIS CODE.
It wiJJ be the responsibility of the repairer to satisfy himself, on
the completion of reclamation, that the apparatus is in a fully
serviceable condition and complies with the Standard(s) for the
relevant explosion protection concept.
1-11
8.4.1
Metal Spraying
This method should be used only when the extent of the wear or damage,
plus the machining necessary to prepare the component part for
reclamation, does not weaken tbe part beyond safe limits. A sprayed
metal inlay, whilst adding some stiffness, should not be taken into
account when strength is considered.
Indeed, the machining process
prior to the application of metal spray may introduce stress raisers
which may further weaken the component.
Detailed procedures are_given in BS 4761.
Metal spraying is not recommended for some high speed, large diameter
applications and is only acceptable where the materials are
metallurgically compahble and the parent base metal is free from
defects.
See also BS 4495 and BS 4950 for other spraying processes.
8.4.2
Electro-plating
Electro-plating is an acceptable procedure provided the part is not
weakened beyond safe limits. Detailed procedures for Chromium and
Nickel plating are given in BS 4641 and 4758 respectively.
8.4.3
Sleeving
This method should be used only when the extent of the wear or damage,
plus the machining necessary to prepare the part for reclamation, does
not weaken the part beyond safe limits. A sleeve, whilst adding some
stiffness, should not be taken into account when strength is
considered.
8.4.4
Brazing or welding
Reclamation by brazing or welding may be considered so long as the
technique employed ensures the correct penetration and fusion of braze
or weld with parent metal, resulting in adequate reinforcement, the
prevention of distortion, the relief of stresses and the absence of
It should be recognised that welding raises the
blow-holes.
temperature of the component to a high level and may cause fatigue
cracks to propagate.
8.4.5
Metal Stitching
The cold reclamation of a fractured casting by tbe technique of closing
the fracture with nickel aHoy stitches and sealing the crack by nickel
aiJoy chain studding may be admissible subject to a suitable thickness
of casting.
8.4.6
Machining of Stator and Rotor Cores (Rotating Machines)
Damaged stator or rotor cores should not be machined (skimmed) without
reference to the manufacturer to ascertain the maximum permissible air
gap, which should not be exceeded.
1-12
This restriction could affect the viability of fitting a new shaft into
an existing core if the core then requires trueing up tq restore
concentricity.
8.4.7
Threaded Holes for Fasteners
Threads which have been damaged to beyond an acceptable extent, may be
reclaimed, depending upon the type of explosion protection, by the
following means -
i)
ii)
iii)
iv)
v)
Oversize drilling and re-tapping
Oversize drilling, re-tapping and the fitting of
a proprietary thread insert
Oversize drilling, plugging, re-drilling and
re-tapping
Plugging, re-drilling and tapping elsewhere
Plug-welding, re-drilling and tapping
8.4.8
Re-Machining
Re-machining worn or damaged surfaces may be considered providing the
component part is not weakened beyond safe limits, provided that the
integrity of the encl0sure is maintained and the required surface
finish is achieved.
9.
Modifications
No modification should be made to certified apparatus unless that
modification is permitted in the certificate or is approved in writing
by the manufacturer. Subsequent parts of this code of practice give
detailed guidance regarding modifications in the context of different
types of protection.
Particular attention is drawn to the need for
care when adding an inverter to an Ex rotating machine in ensuring that
this is done only when the intended combination of inverter and
rotating machine is specified in the certificate or in the rotating
machine manufacturer's documentation. Third Party repairers should
use special care to establish that any inverter on which they are asked
to work is so specified.
Where a modification is proposed which would result in the apparatus
not conforming with either the certification documents or the relevant
explosion protected Standard, the user should be informed in writing
and his written instructions obtained.
If the proposal is carried out
the certification label would be removed (see Section 1 Clause 3.13
page 1-5).
10.
Temporary Repairs
A temporary repair intended to achieve continued short term operation
of apparatus should only be carried out if retention of explosion
Certain temporary repair procedures
protection aspects is ensured.
may thereby be debarred. Any temporary repair should be brought up to
full repair standard as soon as possible.
1-13
11.
Removal of damaged Windings
The procedure of softening the impregnating varnish of windings with
solvents before stripping is acceptable.
The alternative procedure, of the application of heat to facilitate the
removal of windings, is acceptable provided that the operation is
carried out with caution so as not to affect significantly the
insulation between the laminations of magnetic parts.
Particular
caution is necessary and, if in doubt, the advice of the manufacturer
sought regarding the construction of the core and the inter-laminar
insulation material in respect of apparatus with type of protectjon 'e'
and apparatus with any other type of protection having temperature
class T6, T5 or T 4.
The need for particular caution in those circumstances arises from the
fact that an increase in core loss, which could result from degradation
of inter-laminar insulation, could significantly affect type 'e'
parameters (tE time etc.) or result in the temperature classification
being exceedea.
It is the repairer's responsibility to satisfy
himself, as in all reclamation procedures, that on completion of the
reclamation the apparatus is in a fully serviceable condition and
complies with the Standard(s) for the releva nt explosion concept (see
page 1-11, Clause 7.4 Reclamation Procedures).
1-14
Appendix 1
Identification of repaired apparatus by marking
Marking Information
Repairs not affecting the int~ ofthe explosion features need not be marked.
All other repaired and overhauled apparatus should be marked on the main part in a
visible place. 'This marking should be legible and durable taking into account possible
chemical corrosion.
The marking should include;
(i)
the relevant symbol (see below);
(li)
the standard number "IEC 79-19, or national equivalent;
(Iii)
the name of the repairer or his registered trade mark;
(iv)
the repairer's reference number relating to the rt1pair;,
( v)
the date of the overhaul/ repair.
The marking may be on a plate permanently attached to the repaired apparatus.
In the event of subsequent repairs, the earlier plate may be removed, a record being
made of all the markings on it.
Symbols
1.
This mark shall be used when the original certificate is available, and the
apparatus is repaired in full compliance with the certificate and standard.
2. 1bis mark shall be used when the apparatus has been repaired in compliance with
the standard only.
3. The earlier BBAMA AEMT Code of Practice upright triangle, with "R;, mit
should no longer be used.
1 - 15.
( 1QQ~ Revision )
PART1WO ·1YPE OF PROTECTION 'd'- FLAMEPROOF
0
lNTRODUCfiON
This part of the code of practice is intended to complement BS 5345,
Parts 1 and 31 with regard to matters in respect of repair and overhaul
of Ex 'd' apparatus.
A Hst of relevant constructional and testing Standards which should be
referred to when repairing or overhauling Ex 'd' apparatus can be found
in Annex A (Page v).
This part of the code of practice should be read in conjunction with the
General Requirements -Part One of this code.
Type of Protection 'd' - A type of protection in which parts which can
ignite an explosive atmosphere are placed in an enclosure which can
withstand the pressure developed during an internal explosion of an
explosive mixture and wbic:h prevents the transmission of the explosion
to the explosive atmosphere surrounding the enclosure..
SECTION ONE- GENERAL
1.
Scope
This part of the code outlines the requirements of the Manufacturer,
User and Repairer in connection with the repair and overhaul of
electrical apparatus, type of protection 'd', and gives recommendations
as to compliance with apparatus certification requirements and relevant
certification Standards.
SECfiON TWO- REPAIR AND OVERHAUL
1.
Enclosures
i)
It is preferable to obtain new parts from the
manufacturer. Damaged parts may be repaired,
given that the type of protection as stipulated
in the certification documents (if appropriate)
is preserved.
Particular attention should be
paid to the correct assembly of flameproof
enc.losures after repair or overhaul, to ensure
that the joint(s) complies with the .requirements
of the Standard.
Where joints are not
gasketed, they may be protected by the use of
grease, non-setting sealing compound or
non-hardening tape, in accordance with BS 5345,
Paril3.
ii)
Where gaskets which are not part of the
flamepath are incorporated into the flameproof
joints, r_eplacements should be of the same
2-1
materials and dimensions as the original. Any
proposed change of material should be referred
to the apparatus manufacturer, user or
certification authority.
2.
ill)
The drilling of holes into an enclosure is a
modification and should not be carried out
without reference to the manufacturer or, in
exceptional circumstances, to the certifYing
authority.
iv)
c:;are should be taken when changing surface
finish, paint, etc., as this may affect the
surface temperature of the enclosure and thus
the temperature classification.
v)
Before a rewound or repaired rotating machine is
put back into service, it is essential to ensure
that fan cover ventilation holes are not blocked
or so damaged as to impair the passage of
cooling air over the machine, and that any fan
clearances are in compliance with the
requirements of the Standard, if appropriate.
Should a fan or fan cover be so damaged as to
require renewal, the replacement parts must be
of the same dimensions and at least the same
quality as the original parts and should, where
appropriate, take account of the requirements of
the Standard to avoid frictional sparking and
electrostatic charging, and the chernjcal
environment in which the machine is used.
Cable and Conduit Entries
Entries into flameproof enclosures should conform, after repair or
overhau~ to the conditions detailed in the appropriate Standard and/or
certification documents where applicable.
3.
Terminations
Care should be taken when refurbishing terminations to maintain
clearance and creepage distances.
Any replacement terminals,
busrungs, or parts, should conform to the relevant apparatus Standard
and/or certification documents, where applicable.
4.
Insulation
A class of insulation the same as, or superior to, that originally
provided may be employed, e.g. a winding insulated with cJass E
material may be repaired using class F material.
A superior class of insulation compared with that orjginally used does
not permit an increase in apparatus rating without ·r eference to the
manufacturer.
2-2
5.
Internal Connections
There are no particular requirements relating to this type of
protection but repairs to internal connections should be of a standard
at least equivalent to that of the original design.
6.
Windings
6.1
General
The original winding data should preferably be obtained from the
manufacturer; if this is not possible then use may be made of copy
winding techniques. The materials used in rewinding should comprise a
recognised insulation system.
If the system is superior in cJass
to the original, advantage should not be taken to jncrease the rating
of the winding, without reference to the manufacturer, as the
temperature classification of the apparatus could then be adversely
affected.
6.2
Repair of Rotating Machine Rotors
Faulty die cast aluminium rotor cages should be replaced by new rotors
obtained from the manufacturer or his distributor. Bar wound cage
rotors may be rewound using similar materials of identical
specification.
Particular care is necessary to ensure that, when
replacing conductors in a cage rotor, such conductors are tight in the
slots. The method of ~chieving tightness employed by the manufacturer
should be adopted. .
6.3
Testing after Repair of Windings
6.3.1
General
Windings, after complete or partial repair, should be subjected,
preferably with the apparatus assembled, to the following tests, so far
as is reasonably practicable:
a)
The resistance of each winding sbouJd be measured at room
temperature and verified.
In the case of three phase
windings the resistance of each phase, or between line
terminals should be balanced.
b)
An insulation resistance test should be applied to measure
the resistance between the windings and earth, between
windings where possible, between windings and auxiliaries,
and between auxiliaries and earth. A minimum test voltage
of 500 volts d.c. is recommended.
Minimum acceptable insulation resistance values are a
function of rated voltage, temperature, type of apparatus and
whether the rewind is partial or complete.
However, for
example, the insulation resistance should not be Jess than 20
megohms at 20°C on a completely rewound apparatus intended
for use up to 660V.
2-3
6.3.2
c)
A high voltage test in accordance with a relevant Standard
should be applied between windings and earth, between
windings where possible, and between windings and aUXIliaries
attached to the windings.
d)
The apparatus should preferably be energised at rated supply
and the supply current/secondary voltage measured.
The
measured value should be compared with that derived from the
manufacturer•s data, where available, and in three-phases
systems should be balanced in all phases.
e)
High voltage (e.g. lOOOV ac/1500V de and above) and other
special apparatus may require additional tests which should
be agreed with the user or the manufacturer.
Rotating Machines
Rotating machines, in addition to the above tests, should be subjected
to the following tests, so far as is reasonably practicable:
6.4
a)
The machine should be run at full speed and the cause of any
untoward noise and/or vibration investigated and corrected.
b)
The stator windings of cage machines should be energised at
an appropriate reduced voltage, with the rotor locked, to
obtain the full load rated current and to check balance on
all phases.
(The test, which in some respects is an
alternative to a full load test, is 1used to confirm the
integrity of the stator winding and its joints and to
indicate the presence of rotor defects).
c)
High voltage (e.g. 1000V ac/1500V de and above) and non-cage
machines may require alternative and/or additional tests
which should be agreed with the user or n:mnufacturer.
Note:
Guidance on test voltages and additional tests for rotating
machines is given in BS 4999, Part 143.
AuxiliaryEquipment
a)
Temperature sensors
If such sensors are included to monitor winding temperatures,
it is recommended that they are embedded into the winding
before varnishing and curing.
b)
Flameproof brake units
Where a flameproof brake unit attached to a rotating machine
is also certified, and is in need of repair, it is
recommended that it be returned to the manufacturer, together
with the machine. This course is recommended because of the
close construction constraints.
2-4
c)
Other auxiliary devices
Where auxiliary devices are based on different types of
protection, then the corresponding parts of this Code should
be consulted before any repairs are undertaken.
7.
Light Transmitting Parts
No attempt should be made to re-cement or repair light transmitting
parts, and only compl~te replacement assemblies, as specified by the
manufacturer, should be used.
Solvents should not be used for cleaning light transmitting parts made
from plastics. Household detergents are recommended for this purpose.
8.
Encapsulated Parts
In general, encapsulated parts are not considered suitable for repair.
9.
Batteries
Batteries are rarely used in type of protection 'd' apparatus. Where
batteries are employed, the manufacturer's advice should be followed.
10.
Lamps
Lamp types specified by the manufacturer should be used as replacements
and the maximum wattage specified should not be exceeded.
11.
Lampholders
Replacements listed by the manufacturer should be used.
12.
Ballasts
Chokes or capacitors should be replaced only by manufacturer's listed
parts, unless reference is made to the manufacturer to determine if
alternatives may be used.
2-5
SECfiON THREE- RECLAMATION
Reclamations using the techniques detailed in Part One, Section Four, may be
used with type of protection 'd' apparatus subject to the following
restricHons.
1.
Enclosures
Reclaimed component parts of flameproof enclosures may only be used if
they pass, when appropriate, the applicable over-pressure test.
Damag¢ to components .wbich are not an integral part of the flameproof
enclosure, e.g. fixing lugs, may be repaired by welding, or metal
stitching but care is required to ensure that the integrity and
stability of the apparatus is not impaired.
It is particularly
important to check that any cracks being repaired do not extend into
the flameproof enclosure.
The efficacy of reclaiming or repairing by the technique of welding maY'
be further compounded by considerations of different base materials,
e.g. aluminium, cast iron or steel.
It is suggested that if
uncertainty exists the repairer seeks advice, preferably from the
manufacturer, before this technique is adopted.
1.1.
Flameproof Joints
Damaged or corroded flameproof joint faces may be machined after
consultation with the manufacturer wherever possible, providing any
resultant joint gap and flange dimensions are not affected in such a
way that they contravene the construction standard.
It is
particularly important that tbe quality of surface finishes is not
reduced below that allowed for in the Standard, where applicable.
a)
b)
c)
Flanged Joints
Welding, electroplating and re-machining flanged joint faces
may be permissible, having due regard to the limitations of
the technique (Part One). However, metal spraying by the
unfused method is not generally recommended.
Spigoted/CyJindrical Joints
Machining the male part will require addition of metal to,
and machining of, the female part (or vice versa), thus
ensuring that tbe flamepath dimensions comply with the
Standard.
If only one part is damaged, that part may be
restored to its original dimensions by the addition of metal
and re-machining.
The addition of metal may be by
electro-plating, sleeving or welding, but metal spraying by·
the unfused method is not generally recommended.
Threaded Joints
(i) Cable and conduit entries. It is not recommended that
damaged male threaded parts be reclaimed; new components
should be used. Damaged female threads may be repaired
after consultation with the manufacturer.
(ii) Screwed covers. Reclamation of the threaded parts of
screwed covers and of the associated housings may be
impracticable and is not recommended.
2:-6
1.2
Threaded Holes for Fasteners
R~clamation of damaged threaded boles may only be achieved using the
techniques described in Part One, provided that there is due
consultation with the manufacturer and the Standard is not contravened.
2.
Shafts and Housings
Shafts and bearing housings, including flameproof joints, may be
reclaimed, e.g. by the use of metal spraying or sleeving techniques, any
subsequent machining sl1all be to the flamepath dimensions as specified
in the Standard. Welding may be appropriate having due regard to the
limitations of this technique. (See relevant Section of Part 1).
3.
Journals
Journals may be built up by electro-plating or metal spraying.
4.
Rotors and Stators
Rotors and stators may be lightly skimmed to remove eccentricities and
surface damage providing that the resultant increased air gap between
rotor and stator does not result in, for example, change of pressure
piling characteristics or in higher external surface temperatures that
.infringe the temperature class of the machine. It is suggested that if
uncertainty exists with regard to possible detrimental effects the
repairer seeks advice, preferably from the manufacturer, before this
procedure is adopted.
Skimmed or damaged stator cores should be submitted to a "flux test" to
ensure that there are no remaining hot spots which could infringe the
temperature classification or cause subsequent damage to the stator
windings.
SECTION FOUR- MODIFICATIONS
1.
Enclosures
No modification affecting the explosion protection should be carried out
to parts of a flameproof enclosure without reference to the manufacturer
or, in exceptional circumstances, with the certifying authority.
2.
Cable or Conduit Entries
-
Additional entries should not be made without reference to the
manufacturer.
2-7
Indirect entry, where the external conductors are connected by means of
a plug and socket, or within a terminal box, should not be changed to
direct entry, i.e. where the external conductors and cables are
connected within the main enclosure.
3.
Terminations
Termination assemblies contammg a flameproof joint should not be
modified, e.g. terminals with bushings between indirect entry terminal
box and main encl0sure. · Termination assemblies not containing a
flameproof joint may be replaced by alternatives of adequate design and
construction in terms of number, current carrying capacity, creepage
and clearance distances, and quality.
4.
5.
Windings
i)
lt is permissible to rewind apparatus for another voltage,
after reference to the manufacturer, provided that, for
example, the magnetic loading, current densities, and
losses are not increased, appropriate new creepage and
clearance distances are observed and the new voltage is
within the limits of the certification documents.
The
rating plate should be changed to show the new parameters.
ii)
Rewinding a rotating machine for a different speed is not
permissible without reference to the manufacturer, since
the electrical and thermal characteristics of the machine
could be significantly altered so as to take it outside
the limits imposed by the assigned temperature class
(T-rating).
Auxiliary Equipment
In cases where additional auxiliary equipment is requested, e.g.
anti-condensation beaters or temperature sensors, the manufacturer
should be consulted to establish the feasibility of, and procedure for,
the proposed addition.
2-8
PART THREE- TYPE OF PROTECTION 'i'- INTRINSIC SAFE'IY
0.
INTRODUCTION
This code of practice is intended to complement BS 5345 Parts 1 and 4
with regard to matters in respect of repair and overhaul of Ex 'i'
apparatus.
A Jist of relevant constructional and testing Standards, which should be
referred to when a repair or overhaul of Ex 'i' apparatus is to be
carried out, can be found j.n Annex A (Page v).
This code of practice should be read in conjunction with the General
Requirements Part One of this code.
Type of protection 'i' - A circuit ·in which no spark or any thermal
effect pmduced in the test conditions prescribed in the relevant
Standard(s) (which include normal operation and specific fault
condition) is capable of causing ignition of a given explosive
atmosphere.
SECfiON ONE - GENERAL
1.
Scope
This Part of the code outlines the requirements of Manufacturer, User
and Repairer in connection with the repair and overhaul of electrical
apparatus type of protection 'i' and gives recommendations as to
compliance with current apparatus certification requirements, and
relevant certification Standards.
Note; IntrinsicaUy safe equipment may have one of two categories of
approval, Exia and Exib -(for Zone 0 areas only Exia is accepted).
However, the _recommendations for repair and overhaul apply to both
categories and are irrespective of what hazardous area (i.e. Zone 0,
Zone 1 or Zone 2), the equipment is installed. Furthermore, the safety
of intrinsically safe systems depends upon all pieces of apparatus which
form it and upon the interconnecting wiring. The same consideration
should be given to those parts of the system which are installed in the
non-hazardous area as for those parts installed in the hazardous area.
SECfiON TWO -REPAIR AND OVERHAUL
1.
Enclosures
The enclosures of intrinsically safe apparatus are intended to provide a
minimum degree of protection of JP 20 for indoor applications, or a
minimum of IP 54 if the apparatus is used in outdoor applications. Any
repairs should not result in reduction in the degree of protection.
A more stringent degree of protection than that specified in the
Standard may have been provided to cater for environmental conditions,
in which case any repair should not jeopardize such higher degree of
protection.
3-1
2.
Cable Entries
Special entries are used to maintain the required degree of protec6on
of the enclosure.
Any repairs should not result in reduction in the
degree of protection.
3.
Terminations
Care should be taken when refurbishing terminal compartments to
maintain terminal clearances and creepages in accordance with the
Standard.
4.
Fuses
The replacement of fuses should be carried out with care. Replaceable
fuses are normally used to protect transformers and it is important
that the replacement is rated as specified and has the same
characteristics and rupturing capacity.
5.
Relays
H a relay is found to be faulty, the replacement should be obtained
from the equipment manufacturer.
6.
Shunt Diode Safe!)' Barriers
These devices are totally encapsulated and no repair is possible.
It
is not necessary to replace a faulty device with one of exactly the
same type number and manufacture but the replacement should have the
same certification marking and electrical rating.
The replacement
should not degrade the safety of the installation, e.g. by reducing
creepage-clearance distances below those specified in the appropriate
Standard.
7.
Printed Circuit Boards
These parts or the equipment often have critical distances between
conducting tracks (creepage distances) which !;hould not be reduced.
Therefore, when components are replaced care should be taken in
positioning them on the board. Where boards .need to be varnished
after rep~ir, at least two coats of insulating varnish of the type
prescribed by the manufacturer should be paplied in the approved
manner, i.e. brush, dip, coating, etc.
3-2
8.
Optocouplers
Only components of the same or directly equivalent type and
certification should be used as replacements.
9.
Electrical Components
Some component(s), e.g. Zener diodes, of particular type(s) may have
been specialJy selected and only these types may be used as
replacements. Normally these will be obtained only from the equipment
manufacturer.
·
10.
Batteries
Only those types specified in the equipment manufacturer's instructions
should be used as replacements. Where batteries are encapsulated tbe
whole assembly should be.replaced.
11.
Internal Wiring
Certain distances between conductors, and their segregation, are
critical.
Therefore, if disturbed, jnternal wiring should be
re-located in its original position.
12.
Transformers
If a transformer is found to be faulty, the replacement should be
obtained from the equipment manufacturer. No attempt should be made
to repair or replace any embedded (encapsulated) thermal trip device.
13.
Encapsulated Components
Encapsulated components, e.g. batteries with internal current limiting
resistors or fuse-Zener diode assemblies, are non-repairable and should
be replaced only with approved assemblies from the equipment
manufacturer.
14.
Non-Electrical Parts
Where apparatus has non-electrical pans, e.g. fittings or windows,
that do not affect the electrical circuit, or creepage or cJearance
distances and, hence, the intrinsic safety, then these parts may be
replaced by new parts of equivalent type.
3-3
SECTION THREE- RECLAMATION
No attempt should be made to reclaim components on which intrinsic safety
depends.
SECfiON FOUR- MODIFICATIONS
Modifications which may affect the intrinsic safety of the apparatus should not
be carried out without reference to the manufacturer and/or the certification
authority.
Note:
After modification, apparatus should be assessed to ensure that it
complies with the intrinsically safe system documentation before it is
reinstaJJed. It is recommended that this assessment is carried out by
a person other than the one who carried out the modification.
3-4
PART FOUR- TYPE PROTECITON tp'- PRESSURIZED
0.
INTRODUCTION
This part of the code of practice is intended to compliment BS 5345,
Parts 1 and 5, with regard to matters in respect of repair and overhaul
of Ex 'p' apparatus.
A list of relevant constructional and testing Standards, which should
be referred to when a repair or overhaul of Ex 'p' apparatus is to be
carried out, can be faun~ in Annex A (Page v).
This part of the code of practice should be read in conjunction with
the General Requirements - Part One of this code.
Type of protection tp• - A type of protection by which the entry of a
surrounding atmosphere into the enclosure of the electrical apparatus
is prevented by maintaining, inside the said enclosure, a protective
gas at a higher pressure than that of the surrounding atmosphere. The
overpressure is maintained either with or without a continuous flow of
the protective gas. ·
SECfiON ONE- GENERAL
1.
Scope
This part of the code outlines the requirements of the Manufacturer,
User and Repairer in connection with the repair and overhaul of
electrical apparatus, type of protection 'p', and gives recommendations
as to the compliance with current apparatus certification requirements
and relevant Standards.
SECTION TWO -REPAIR AND OVERHAUL
1.
Enclosures
l.l
While it is preferable to obtain new parts from the manufacturer, in
principle, a damaged part may be repaired or replaced with another
given that, when compared with the original, it:
i)
is of at least equivalent strength;
ii)
does not result in a greater leakage rate of
protective gas;
iii)
does not restrict the flow of protective gas
jnto or through the enclosure;
4-1
iv)
is not shaped or fitted so as to permit the
potentially explosive atmosphere to enter the
enclosure;
v)
is not of a construction which would result in
stagnant volumes of atmosphere inside the
enclosure;
vi)
does not reduce the rate of heat dissipation
from the enclosure or its contents.
1.2
Gaskets or other sealing devices should be replaced with others of the
same materiaL
However a different gasket material may be used
provided that it is suitable for its purpose and is compatible with the
environment.
2.
Cable and Conduit Entries
Entries should preserve the degree of protection originally provided,
and should not allow increased leakage of protective gas.
3.
Terminations
There are no specific requirements but the preservation of creepage and
clearance distances as originally provided should be ensured.
4.
Insulation
Any replacement insulation used in the course of repair or overhaul
should be at least of the quality and class of that originally
employed.
5.
Internal Connections
There are no particular requirements but internal connections should
not be electrically, thermally or mechanically inferior to those
originally fitted and should be of a standard at least equivalent to
that of the original design.
6.
Windings
6.1
General
The original winding data should preferably be obtained from the
manufacturer; if this is not possible then use may be made of copy
winding techniques. The materials used in rewinding should comprise a
If superior in class to the original,
recognised insulation system.
advantage should not be taken to increase the rating of the winding as
the temperature classification of the apparatus could then be adversely
affected.
4-2
6.2
Repair of Rotating Machine Rotors
Faulty die cast aluminium rotor cages should be replaced by new rotors
obtained from the manufacturer or his distributor. Bar wound cage
rotors may be rewound using similar materials of identical
sp~cification.
Particular care is necessary to ensure that, when
replacing conductors in a cage rotor, such conductors are tight in the
slots. The method of achie:vi:ng tightness employed by the manufacturer
should be adopted.
6.3
Testing after Repair of Windlings
6.3.1
General
Windings, after complete or partial repair, should be subjected,
preferably with the apparatus assembled, to the following tests, so far
as is reasonably practicable:
a)
The resistance of each winding should be measured at room
temperature and verified.
In the cas~ of three phase
windings the re1sistance of each phase, or between Une
terminals should be balanced.
b)
An insulation resistance test should be applied to measure
the resistance between the windings and earth, between
windings where possible, between windings and ~uxiliaries,
and between amdiliaries and earth. A minimum test voltage
of 500 volts d.c. is recommended.
Minimum acceptable insulation resistance values are a
function of rated voltage, temperature, type of apparatus and
whether the rewind is partial or complete. _ However, for
example, the ins-ulation resistance should not be less than 20
megohms at 20°C on a completely rewound apparatus· intended
for use up to 660V.
c)
A high voltage t'est, jn accordance with a relevant Standard,
should be applied between wjndings and earth, between
windings where possible, and between windings and ·auxiliaries
attached to the windings.
d)
The apparatus should preferably be energised at rated supp'ly
and the supply current/secondary voltage measured.
The
measured value slhould be compared with that derived from the
manufacturer's data, where available, and in three-phase
systems should be balanced in :au phases.
e)
High voltage (e.~~· 1000V ac/1500V de and above), and otller
special apparatus may require additional tests wrucb should
be agreed with the user or manufacturer.
4-3
6.3.2
Rotating Machines
Rotating machines, in addition to the above tests, should be subjected
to the following tests, so far ~ts is reasonably practicable:
a)
The machine shnuld be run at full speed and the cause of any·
untoward noise amd/or mechanical V'ibration investigated and
corrected.
b)
The stator windings of cage machines should be energised at
an appropriate ~reduced voltage, with the rotor locked, to
obtain the fuU load rated current and to ensure balance on
all phases.
(The test, which in some respects is an
alternative to a full load test, is used to confirm the
integrity of the~ stator winding and its joints and to
indicate the presence of rotor defects).
c)
High voltage (e.g.. lOOOV ac/1500V de and above) and non-cage
machines may 1require alternative and/or additional tests
which should be agreed with the user or manufacturer.
Guidance on tes:t voltages and additional tests for rotating
machines is given in BS 4999, Part 143.
7.
Light Transmitting Parts
Solvents should not be used for cleaning light transmitting parts made
from plastics. Household detergents are recommended for this purpose.
8.
Encapsulated Parts
In general, encapsulated parts are not considered suitable for repair.
9.
Batteries
Batteries are rarely, if ever, used in type of protection 'p'
apparatus. Where batter.ies are employed, the manufacturer's advice
should be sought.
10.
Lamps
Lamp types specified by the~ manufacturer should be used as replacements
and the maximum wattage specified should not be exceeded~
11.
Lampholders
Replacements listed by the manufacturer should be used.
4-4
12.
Ballasts
Chokes or capacitors should be replaced only by manufacturer's listed
parts, unless reference is made to the manufacturer to de termine if
alternatives may be used.
SECfiON THREE- RECLAMATION
Reclamation using the techniques detailed in Part One, Section Four, may be
used with type of protection 'p' equipment subject to the following
restrictions:
1.
Enclosures
Damage to enclosures, terminal boxes and covers may be repaired by
welding or metal stitching but care is necessary to ensure that the
integrity of the apparatus is not significantly impaired as to degrade
the type of protection, in particular, that it remains capable of
withstanding the impact test and the appropriate level of overpressure.
1.1
Joints
Damaged or corroded ·joint faces may be machined provided that the
mechanical strength and operation of the component is not impaired and
the degree of protection is not affected.
Spigoted joints are normally provided to achieve close tolerance
location.
Thus, machining the male part will require addition of
metal to, and the machining of, the female part (or vice versa) to
retain the location p roperties of the joint.
If only one part is
damaged, that part may be restored to its original dimensions by the
addition of metal and re-machining. The addition of metal may be by
electro-plating, sleeving, or welding, but metal spraying by the
unfused method is not generally recommended.
1.2
Threaded Holes
Reclamation of damaged threaded holes may be achieved using the
techniques descnbed in Part One of this code.
2.
Shafts and Housings
Shafts and bearing housings may be reclaimed, preferably by use of
metal spraying or sl~eving techniques.
Welding may be appropriate
having due regard to the limitations of this technique, see Part One of
this code.
4-5
3.
Journals
Journals may be built up by electro-plating or metal spraying.
4.
Rotors and Stators
Rotors and stators may be lightly skimmed to remove eccentricities and
surface damage, after consultation with the manufacturer, providing
that the resultant increased air gap between rotor and stator does not
result in higher external surface temperatures that infringe the
temperature class of the .machine.
Skimmed or damaged stator cores should be subjected to a "flux test" to
ensure that there are no remaining hot spots which could infringe the
temperature classification or cause subsequent damage to the stator
windings.
SECfiON FOUR- MODIFICATIONS
1.
2.
Enclosures
i)
Enclosures not containing a source of release of
flammable gas may be modified. Any modified
part should meet the conditions given in Section
Two: Clause 1.1.
ii)
Enclosures with an internal source of release of
flammable gas such as analysers, chromatographs,
etc. should not be modified in any way
whatsoever
without
reference
to
the
manufacturer.
iii)
The point(s) at which the level of overpressure
and the rate of flow of purging gas is (are)
monitored should not be altered nor should the
setting of any timer or other monitoring devices
be changed.
Cable and Conduit Entries
Special care to be taken that if alteration is made to entries the
specified type and degree of protection are maintained.
3.
Terminations
Modification of terminations may be made using good engineering
practices.
4-6
4.
5.
Windings
i)
It
ii)
Re·winding a rotating machine for a different
speed is not permissible without reference to
the manufacturer, since the electrical and
thermal characteristics of tbe machine could be
signiificantly altered so as to take it outsjde
the limits imposed by the assigned temperature
class (T-rating), if appropriate, and the
efficacy of the pressurizing system could be
jeopardized.
iis permissible to rewind apparatus for
another voltage, after reference to the
manufacturer, provided that, for example, the
magnetic loading, current densities and losses
are :not increased, appropriate new creepage and
clea1rance distances are observed and the new
voltage
is
within
the
limits
of the
certi~fication documents.
The rating plate
should be changed to show the new parameters.
Auxiliary Equipment
In cases where additional auxiliary equipment is requested, e.g.
anti-condensation beaters or temperature sensors, the manufacturer
should be consulted to establish the feasibility of, and procedure for,
the proposed addition.
4-7
PART FIVE -1YPE OF PROTECTION 'e'- INCREASED SAFE1Y
0.
INTRODUCfiON
This part of the code of practice is intended to compliment BS 5345,
Parts 1 and 6, with regard to matters in respect of repair and overhaul
of Ex 'e' apparatus.
A list of relevant constructional and testing Standards, which should
be referred to when a repair or overhaul of Ex 'e' apparatus is to be
carried out, can be found.in AnnexA (Page v).
This part of the code of practice should be read in conjunction with
the General Requirements - Part One of this code.
Type of Protection 'e' - A type of protection by which measures are
applied so as to prevent, with a higher degree of security, the
possibility of excessive temperatures and of the occurrence of arcs or
sparks in the interior and on the external parts of electrical
apparatus which does not produce them in normal service.
SECfiON ONE- GENERAL
t.
Scope
This part of the Code outlines the requirements of Manufacturer, User
and Repairer in connection with the repair and overhaul of Electrical
Apparatus type of protection 'e' and gives recommendations as to
compliance with apparatus certification requirements, and relevant
certification Standards.
SECTION TWO - REPAIR AND OVERHAUL
1.
Enclosures
1.1
While it is preferable to obtain new parts from the manufacturer, in
principle, damaged parts may be repaired or replaced with others, given
that the degree of protection and temperature classification as
stipulated on the certification label are preserved.
1.2
A more stringent degree of protection than that specified in the
Standard may have been provided to cater for environmental conditions,
in which case any ,epair should not jeopardize such higher degree of
protection.
1.3
Particular attention is drawn to impact test requirements of all parts
of the enclosure, and also the degree of protection to be provided for
air inlet and outlet openings, as given in the apparatus Standard.
1.4
Adequate clearance should be maintained between stationary and rotating
parts in accordance with the Standard.
5-1
1.5
Attention is drawn to the effects of surface finishes, paint, etc. on
the temperature classification of enclosures.
Only finishes specified
by the manufacturer should be applied.
1.6
Before a rewound or repaired rotating machine is put back into service,
it is essential to ensure that any fan cover ventilation holes are not
blocked or so damaged as to impair the passage of cooling air over the
machine, and that fan clearances are in compliance with the
certification requirements. Should a fan or fan cover be so damaged
as to require renewal, the replacement parts should be of the same
dimensions as the original and at least of the same quality of the
original parts, and s~ould where appropriate take . account of the
requirement of the Standard to avoid frictional sparking . and
electrostatic charging, and the chemical environment in which the
machine is used.
2.
Cable or Conduit Entries
Entries should preserve IP54 minimum . degree of protection or such
higher degree of protection as may have been provided - see cJause 1.2,
page 5-1.
3.
4.
Terminations
i)
The design of terminations in terms of the
materials used, the creepage and clearance
distances and the comparative tracking indices
of termination insulation, will normally be
fully
specified
in
the
certification
documents. Replacement parts should preferably
be obtained from the manufacturer or his advice
sought regarding acceptable alternatives.
ii)
Where terminations are loose leads the methods
of termination, including insulation, should be
in accordance with the certification documents.
Insulation
Comprehensive details of the insulation system of windings, including.
the type of impregnation varnish, are normally incJuded in the
certification documents.
Full information should be sought from the
manufacturer.
5.
Internal Connections
Internal connections may be renewed, given that any insulation on such
connections is not electrically, thermally or mechanically inferior to
that originally supplied.
The _cross-sectional area of any replacement connection should not be:
less than that originally fitted.
5-2
The permitted methods of connecting conductors are given in the
relevant Standards.
6.
Windings
6.1
General
The electrical construction of a type of protection 'e' apparatus
decisively influences the explosion safety and the repairer should be
in full possession of the necessary information and equipment
Unless the repairer c·a n meet all the requirements it should be
recognised that the rewinding should be carried out by the original
manufacturer as intimated in BS 5345 Part 1.
Before the repair, the original winding data should lbe obtained, i.e.
Type of Winding- e.g. single layer, double layer, etc.
Winding diagram
Number of conductors/slot, parallel path:s per phase
Interphase connections
Conductor size
Insulation system, including varnish specification
Resistance/phase or between terminals
The winding data should generally be available from the manufacturer.
It is necessary to restore the windings to the ~original condition, this
applies to the whole of the winding. It is not recommended to have a
partial winding replacement, except on larger apparatus where this may
be practicable, unless reference bas been made to the manufacturer or
certifying authority.
6.2
Repair of Rotating Machine Rotors
Rotors with faulty die cast aluminium cages s.h ould be replaced by
completely new rotors obtained from the manufacturer or his
distnlmtor.
Bar wound cage rotors may be rewound using materials of identical
specifications.
Particular care is necessary to ensure that if
replacing conductors in a cage rotor, such conductors are tight in the
slots. The method of achieving tightness employ1ed by the manufacturer
should be adopted.
6.3
Testing After Repair of Windings
6.3.1
General
Windings, after complete repair, should be su~jected, preferably with
the apparatus assembled, to the following tests so far as is reasonably
practicable:
5-3
6.3.2
a)
The resistance of each winding should be measured at room
temperature and verified.
In the case of three phase
windings the resistance of each phase, or between line
terminals should be balanced.
b)
An insulation resistance test should be applied to measure
the resistance between the windings and earth, between
windings where possible, between windings and auxiliaries,
and between auxiliaries and earth. The minimum test voltage
of 500 volts de is recommended.
Minimum acceptable
insulation resistance values are a function of rated voltage,
temperature and type of apparatus. However, for example,
the insulation resistance should not be less than 20 megohms
at 20°C on a completely rewound apparatus intended for use
up to 660V.
c)
A high voltage test, in accordance with a relevant Standard,
should be applied between windings and earth, between
windings where possible, and between windings and auxiliaries
attached to the windings.
d)
The apparatus should preferably be energised at rated supply
and the supply current/secondary voltage measured.
The
measured value should be compared with that derived from the
manufacturer's data, where available, and in three-phase
systems should be balanced in an phases.
e)
Hig~ voltage (e.g. lOOOV ac/1500V de and above) and other
special apparatus may require additional tests which should
be agreed with the user or manufacturer.
Rotating Machines
Rotating machines, in addition to the above tests, should be subjected
to the following tests so far as is reasonably practicable:
a)
The machine should be run at full speed and the cause of any
untoward noise and/or mechanical vibration investigated and
corrected.
b)
The stator windings of cage machines should be energised at
an appropriate reduced voltage, with the rotor locked, to
obtain the full load rated current and to ensure balance on
all phases.
(The test, which in some respects is an
alternative to a full load test, is used to confirm the
integrity of the stator winding and its joints and to
indicate the presence of rotor defects).
c)
High Voltage (e.g. 1OOOV ac/1500V de and above) and non-cage
machines may require alternative and/or additional tests
which should be agreed with the user or manufacturer.
Note:
Guidance on test voltages and additional tests for rotating
machines is given in BS 4999, Part 143.
5-4
6.4
Auxiliary Equipment
If temperature sensors are incJuded to monitor winding temperatures, it
is recommended that they are embedded into the winding before
varnishing and curing.
7.
Light Transmitting Parts
No attempt should be made to repair light transmitting parts and only
replacement components provided by the manufacturer should be used.
Solvents should not be used for cleaning light transmitting or other
parts made of plastic. Household detergents may be used.
8.
Encapsulated Parts
In general, encapsulated parts are not considered suitable for repair
or reclamation.
9.
Batteries
Where type of protection 'e' apparatus contains batteries of any kind,
reference should be made to the manufacturer~s instructions before
carrying out any·repair or replacement.
10.
Lamps
Lamp types specified by the manufacturer should be used as replacements
and the maximum wattage specified should not be exceeded.
Special care should be taken with the special single pin tubular
fluorescent tube employed for type of protection 'e' luminaires. The
single pin, when inserted in the Jampholder, forms a flameproof
enclosure and distortion or misalignment may affect the designed
explosion protection.
11.
Lampholders
Lampholders for type of protection 'e' luminaires are invariably of
specific types, either single pin for tubular fluorescent lamps or
screw for other types.
Only replacements specified by the manufacturer should be used. In
those cases where the wiring to the lampholder is factory made (crimps
etc.) rewiring should not be undertaken unless the repairer has the'
equipment to make up the wiring to the same standard.
12.
Ballasts
Defective chokes and capacitors should only be replaced with
manufacturer's listed parts.
SECTION THREE-RECLAMATION
Reclamations using the techniques detailed in Part One, Section Four, may be
used with type of protection 'e' equipment subject to the following
restrictions:
1.
Enclosures
Minor damage to enclosures, terminal boxes and covers can be repaired
by welding or metal stitching but care is necessary to ensure that the
integrity of the apparatus is not significantly impaired as to degrade
the type of protection, in particular, that it remains capable of
withstanding the impact test and maintains the degree of protection.
1.1
Joints
Damaged or corroded joint faces may be machined providing that the
mechanical strength and operation of the component is not impaired and
the degree of protection is not affected.
Spigoted joints are normally provided to achieve close tolerance
location.
Thus, machining the male part will require addition of
metal to, and machining of, the female part (o.r vice versa) to retain
the location properties of the joint.
If only one part is damaged,
that part may be restored to its original dimensions by the addition of
metal and re-machining.
The addition of metal may be by
electro-plating, sleeving, or welding, but metal spraying by the
unfused method is not generally recommended.
12
Threaded Holes
Reclamation of damaged threaded holes may be achieved using the
techniques described in Part One of this code.
2.
Shafts and Housings
Shafts and bearing housings may be reclaimed, preferably by use of
metal spraying or sleeving techniques.
Welding may be appropriate
having due regard to the limitations of this technique, see Part One of
this code.
3.
Journals
Journals may be built up by electro-plating or metal spraying.
5-6
4.
Rotors an Stators
Rotors and stators may be lightly skimmed to remove eccentricities ~nd
surface damage, after consultation with the manufacturer, providing
that the resultant increased air gap between rotor and stator qoes not
result in-
i)
higher
internal
and/or
external
surface
temperatures that infringe the temperature class
of the machine, or
ii)
changes in electrical/mechanical performance
whicb prevents the electrical/thermal protective
devices providing the tripping characteristics
required to confonn to the Standard.
Skimmed or damaged stator cores should be subjected to a "flux test" to
ensure that there are no remailling hot spots whjcb could infrin,g e the
temperature classification or cause subsequent damage to the stator
windings.
SECTION FOUR- MODIFICATIONS
1.
Enclosures
Enclosures may be modified provided that the specified temperature
classification, degree of protection, and impact test requirements are
met.
2.
Cable and Conduit Entries
Special care to be taken that if alteration is made to entries the
specified type and degree of protection is maintained.
3.
Terminations
No modification of terminations should be made without reference to the
manufacturer.
•
4.
Windings
i)
..
It is permissible to rewind apparatus for
another voltage, after reference to the
manufacturer, provided that, for example, the
magnetic loading, current densities and losses
are not increased, new appropriate creepage and
clearance distances are observed, and the new
voltage, tE time and I AIIN ratio are
within
the
limits
of the
certification
documents. The rating plate should be changed
to show the new parameters.
5-7
4.
Rotors an Stators
Rotors and stators may be lightly skimmed to remove eccentricities and
surface damage, after consultation with the manufacturer, providing
that the resultant increased air gap between rotor and stator does not
result in-
i)
higher internal
and/or
external
surface
temperatures that infringe the temperature class
of the machine7 or
ii)
changes in electrical/mechanical performance
which prevents the e}ectricalf.thermal protective
devices providing the tripping characteristics
required to conform to the Standard.
Skimmed or damaged stator cores should be subjected to a "flux test" to
ensure that there are no remaining hot spots which could infringe the
temperature cJassification or cause subsequent damage to the stator
windings.
SECTION FOUR- MODIFICATIONS
1.
EnClosures
Enclosures may be modified provided that the specified temperature
classification, degree of protection, and impact test requirements are
met.
2.
Cable and Conduit Entries
Special care to be taken that if alteration is made to entries the
specified type and degree of protection is maintained.
3.
Terminations
No modification of terminations should be made without reference to the
manufacturer.
4.
Windings
i)
It is permissible to rewind apparatus for
another voltage, after reference to the
manufacturer, provided that, for example, the
magnetic loading, current densities and losses
are not increased, new appropriate creepage and
clearance distances are obse.r;ved, and the new
v~lt~ge,
tE ti_!ll: and I A/IN rat~o ~re
Withm
the
linuts
of the
certification
documents. The tating plate should be changed
to show the new parameters.
5-7
li)
5.
Rewinding a rotating machine for a different speed is not
permissible without reference to the manufacturer, since the
electrical and tbermal characteristics of the machine could
be significantly altered so as to take it outside the limits
of the certificatiom documents.
Auxilia!Y Equipment
In cases where additional auxiliary equipment is requested, e.g.
anti-condensation heat~rs or temperature sensors, the manufacturer
should be consulted to establish the feasibility of, and procedure for,
the proposed modification.
5-8
PART SIX- TYPE OF PROTECI'ION 'N~ OR 'n'- NON SPARKING
0.
INTRODUCTION
This part of the code of practice is intended to complement BS 5345,
Parts 1 and 7, with regard to matters in respect of repair and overhaul
of Ex 'N' apparatus.
A list of relevant constructional and testing Standards, which should
be referred to when a repair or overhaul of Ex 'N' apparatus is to be
carried out, can be found in Annex A (Page v).
This part of the code of practice should be read in conjunction with
the General Requirements -Part One of this code.
Type of Protection 'N' or <n• - A type of protection applied to
electrical apparatus such that, in normal operation, it is not capable
of igniting the surrounding explosive atmosphere, and a fault capable
of causing ignition is not likely to occur.
SECTION ONE - GENERAL
1.
Scope
This part of the code outlines the requirements of the Manufacturer,
User and Repairer in connection with the repair and overhaul of
electrical apparatus type of protection 'N' or 'n' and gives
recommendations as to compliance with apparatus certification
requirements and relevant certification Standards.
SECTION TWO -REPAIR AND OVERHAUL
1.
Enclosures
1.1
Whilst is is preferable to obtain new parts from the manufacturer, in
principle, damaged parts may be repaired or replaced with others, given
that the degree of protection and temperature classification as
stipulated on the certification label is preserved.
1.2
A more stringent degree of protection than that specified in the
Standard may have been provided to cater for environmental conditions,
in which case any repair should not jeopardise such higher degree of
protection.
1.3
Particular attention is drawn to the impact test requirements of all
parts of the enclosure, as given in the apparatus Standard.
1.4
Adequate c1earance should be maintained between stationary and rotating
parts in accordance with the Standard.
'6-1
1.5
Restricted breathing enclosures depend for their explosion protection
on gaskets and other means of sealing. Particular attention should be
paid to the condition of the sealing arrangements to preserve the type
of protection.
1.6
Attention is drawn to the effect of surface finish, paint, etc-. on the
temperature classification of enc1osures.
1.7
Before a rewound or repaired rotating machine is put back into service,
it is essential to ensure that any fan cover ventilation holes are not
blocked or so damaged as to impair the passage of cooling air over the
machine and that fa.n clearances are in compliance with the
certification requirements. Should a fan or fan cover be so damaged
as to require renewal, the replacement parts should be of the same
dimensions as the original and at least the same quality of the
original parts, and should, where appropriate, take account of the
requirement of the Standard to avoid frjctional sparking or
electrostatic charging and the chemical environment in which the
machine is used.
2.
Cable and Conduit Entries
Entries should preserve the specified degree of protection.
3.
4.
Terminations
i)
Care should be taken when refurbishing terminal
compartments to maintain clearances and
creepages in accordance with the Standard.
Where non-metallic screws are used for fixing
then only replacement screws of similar
materials may be used.
ii)
Where terminations are loose leads the method of
termination, including insulation~ should be in
accordance with the certification documents.
Insulation
A class of insulation the same as, or superior to, that originally
provided should be employed.
If superior in class to the original, advantage should not be taken to
increase the rating of the winding as the temperature classification of
the apparatus could then be adversely affected.
5.
Internal Connections
Internal connections may be renewed, given that any insulation on such
connections is not electrically, thermally or mechanically inferior to
that originally supplied.
6-2
The cross-sectional area of any replacement connection should not be
less than that originally fitted.
6.
Windings
6.1
General
Where rewinding is carried out, it is essential that the original
winding data are determined and that the new winding conforms to the
original.
The original winding data should preferably be obtained from the
manufacturer; if this is not possible then use may be made of copy
winding techniques.
It is not recommended to have a partial winding replacement, except on
larger apparatus where this may be practicable, unless reference has
been made to the manufacturer or certifying authority.
6.2
Repair of Rotating Machine Rotors
A faulty die cast aluminium rotor should be replaced by a complete new
rotor obtained from the manufacturer or his distributor.
Bar wound cage rotors may be rewound using materials of equivalent
specification.
Particular care is necessary to ensure that, if
replacing conductors in a cage rotor, such conductors are tight in the
slots. The method of acrueving tightness employed by the manufacturer
should be adopted.
6.3
Testing After Repair of Windings
6.3.1
General
Windings, after complete or partial repair, should be subjeCted,
preferably with apparatus assembled, to the fol1owing tests so far as
is reasonably practicable:
a)
The resistance of each winding should be measured at room
temperature and verified.
In the case of three phase
windings the resistance of each phase, or between line
terminals should be balanced.
b)
An insulation resistance test should be applied to measure
the resistance between the windings and earth, between
windings where possible, between windings and auxiliaries,
and between auxi1iaries and earth. A minimum test voltage
of 500 volts de is recommended.
Minimum acceptable insulation resistance values are a
function of rated voltage, temperature, type of apparatus and
whether the rewind is partial or complete.
However the
insulation resistance should not be less than 20 megohms, at
20°C, on a completely rewound apparatus intended for use at
up to 650 volts.
6-3
6.3.2
c)
A high voltage test in accordance with a relevant Standard
should be applied between windings and earth, between
windings where possible, and between windings and auxiliaries
attached to the windings.
d)
The apparatus should preferably be energised· at rated supply
and supply current/secondary voltage measured. The measured
value should be compared with that derived from the
manufacturer's data, where available, and in three-phase
systems should be balanced in all phases.
e)
High voltage .(e.g. lOOOV ac/1500V de and above) and other
special apparatus may require additional tests which should
be agreed with the user or manufacturer.
Rotating Machines
Rotating machines, in addition to the above tests, should be subjected
to the following tests so far as is reasonably practicable:
a)
The machine should be run at full speed and the cause of any
untoward noise and/Or mechanical VIbration investigated and
corrected.
b)
The stator windings of cage machines should be energised at
an appropriate reduced voltage, with the rotor locked, to
obtain the full load rated current and to ensl:lre balance on
all phases.
(The . test, which in some respects is an
alternative to a full load test, is used to confirm the
integrity of the stator winding and its joints and to
indicate the presence of rotor defects).
c)
High voltage (e.g. 1000V ac/1500V de and above) and non-cage
machines may require alternative and/or additional tests
which should be agreed with the user or manufacturer.
Guidance on test voltage and additional tests for rotating
machines is given in BS 4999, Part 143.
6.4
Auxiliary Equipment
H temperature sensors are included to monitor winding temperatures, it
is recommended that they are embedded into the winding before
varnishing and curing.
6-4
1.
Light Transmitting Parts
Solvents should not be used for cleaning light transmtttmg or other
parts made of plastic. HousehoJd detergents may be used.
8.
Encapsulated Parts
In general, encapsulated parts are not considered suitable for repair.
9.
Batteries
Where type of protection 'N' or 'n' apparatus contains batteries of any
kind, reference should be made to the manufacturer's instructions
before carrying out any repair or replacement.
10.
Lamps
Lamp types specified by the manufacturer should be used as replacements
and the maximum wattage specified should not be exceeded.
11.
Lampholders
Replacements listed by the manufacturer should be used.
12.
Ballasts
Chokes or capacitors should only be replaced with manufacturers listed
If these are of proprietary manufacture reference should be
parts.
made to the original manufacturer to determine if alternatives may be
used.
13.
Enclosed Break Devices
In general enclosed break devices are not considered to be suitable for
repair. Replacement parts listed by the manufacturer should be used.
SECTION THREE- RECLAMATION
Reclamations using the techni9,ues detailed in Part One of the code may be used
with type of protection 'N or 'n' equipment subject to the foUowing
restrictions:
6-5
1.
Enclosures
Minor damage to enclosures, terminal boxes and covers may be repaired
by welding or metal stitching but care is necessary to ensure that the
integrity of the apparatus is not impaired, in particular, that it
remains capable of withstanding the impact test and maintains the
degree of protection.
2.
Joints
Damaged or corroded joint faces may be machined providing that the
mechanical strength and operation of the component is not impaired and
the degree of protection is not affected.
Spigoted joints are normally provided to achieve close tolerance
location.
Thus, machining the male .part wilJ require addition of
metal to, and machining of, the female part (or vice versa) to retain
If only one part is damaged,
the location properties of the joint.
that rart may be restored to its original dimensions by the addition of
meta and re-machining.
The addition of metal may be by
electroplating, sleeving, or welding, but metal spraying by the unfused
method is not generally recommended.
3.
Threaded Holes
Reclamation of damaged threaded holes may be achieved using the
techniques described in Part One of the code.
4.
Rotating Machines
i)
Shafts and Housings
Shafts and bearing housings may be reclaimed,
preferably by use of metal spraying or sleeving
techniques. Welding may be appropriate having
due regard to the limitations of this technique
-Part One of this code.
ii)
Journals
Journals may be built up by electroplating or
metal spraying.
iii)
Rotors and Stators
Rotors and stators may be lightly skimmed to
remove eccentricities and surface damage,
providing that the resultant increased air gap
between rotor and stator does not result in
higher internal or external surface temperatures
that infringe the temperature class of the
machine.
6-6
Skimmed or damaged stator cores should be
subjected to a "flux test" to ensure that there
are no remaining hot spots which could infringe
the
temperature
classification
or
cause
subsequent damage to the stator windings.
SECTION FOUR- MODIFICATIONS
1.
Enclosures
Enclosures may be modified provided that the specified temperature
classification, degree of protection and impact test requirements are
met.
2.
Cable and Conduit Entries
Care should be taken to ensure that the specified type and degree of
protection is maintained.
3.
Terminations
May be modified provided that compliance with the Standard is
maintained.
4.
5.
Windings
i)
It is permissible to rewind apparatus for
another voltage, after reference to the
manufacturer, provided that, for example, the
magnetic loading, current densities and losses
are not increased, appropriate new clearances
and creepage distances are observed, and the new
is within .the limits
of the
voltage
certificate.
The rating plate should be
changed to show the new parameters.
ii)
Rewinding a rotating machine for a different
speed is not permissible without reference to
the manufacturer since the electrical and
thermal characteristics of the machine could be
significantly altered so as to take it outside
the limits of the certification documents.
Amoliary Equipment
In cases where additional auxiliary equipment is requested, e.g.
anti-condensation beaters or temperature sensors, the manufacturer
should be consulted to establish the feasibility of, and procedure for,
the proposed modification.
6-7
PART SEVEN -'IYPE OF PROTECI'ION 's' - SPECIAL PROTECfiON
0.
INTRODUCTION
This code of practice is intended to complement BS 5345, Parts 1 and 8,
wi!h regard to the matters in respect of repair and overhaul of Ex 's'
apparatus.
A list of relevant constructional and testing Standards containing
specific requirements can be found in Annex A (Page v).
This code of practice should be read in conjunction with the General
Requirements - Part One of this code.
Type of protection 's' - Electrical equipment which is considered safe
due to design features other than the formal concepts covered by
National Standards, may be certified as specially protected.
SECTION ONE- GENERAL
1.
Scope
This part of the code outlines the requirements of Manufacture rs, Users
and R epairers in connection with the repair and/or overhaul of
electrical apparatus having type of protection 's', particularly
withregard to its compliance with the relevant Standards.
Type 1s' is an exceptional case having regard to the fact that it
covers a wide variety of applications.
Repair or overhaul should be
contemplated with caution and reference should be made to the
manufacturer in the first instance. Some equipment is only capable of
repair or overhaul by the manufacturer.
SECTION TWO - REPATR AND OVERHAUL
1.
Enclosures
Where apparatus of type of protection 's' is enclosed by another type
of protection, the repair or overhaul of the enclosure shouJd conform
with the appropriate Part of this code.
Where the enclosure is of
type of protection 's', there are no general rules for repair or
overhaul and references shouJd be made to the manufacturer for advice.
7-1
2.
Cable and Conduit Entries
Entries complying with other types of protection should be
repaired/overhauled in compliance with the appropriate Part of this
Code.
There are no general rules for the repair or overhaul of
entries to type of protection 's' and reference should be made to the
manufacturer for advice.
3.
Terminations
Terminations complying with other types of protection should be
repaired/overhauled in compliance with the appropriate Part of this
code.
There are no general rules for the repair or overhaul of
terminations to type of protection 's' and reference should be made to
the manufacturer for advice.
4.
Encapsulated Apparatus
In many cases it is not possible to repair or overhaul apparatus which
has been encapsulated.
Indeed, it is unwise even to attempt to
replace or repair the encapsulation itself, except where spedfically
recommended by the manufacturer.
However, apparatus in which part is type of protection 's', the
encapsulation may be repairable or amenable to overhaul if it is the
form of a complete, detachable sub-assembly.
In such cases it is
necessary to ensure that the encapsulated part is free from defects
(electrical or mechanical) such as:
cracks in the encapsulation,
overheated parts, Jack of adhesion of encapsulation from associated
parts such as printed circuit boards, chemical attack, etc., and if
not, to replace the whole encapsulated part.
5.
Flame Arrestors
Flame arrestors should be inspected for physical damage, such as
cracks, and for contamination/blockage by dirt, corrosion or paint, and
be replaced by a new part, if necessary, obtained only from the
manufacturer or his authorised suppUers.
6.
Batteries
Apparatus containing primary or secondary ceUs may be repaired or
overhauled only where the cells are intended to be replaced.
No attempt should be made to replace encapsulated cells or batteries
except where the complete encapsulated assembly may be replaced.
7-2
7.
Lamps
Factory-sealed handlamps should be returned to the manufacturer for
repair or replacement as appropriate. Where lamps are enclosed by
avparatus .of other types of protection combined with type of protection
's , reference should be made to .other parts of this code (as
appropriate) and to the manufacturers' instructions.
8.
Lampholders
Where lampholders are covered by other types of protection combined
wjth type of protection ·•s•, reference should be made to other Parts of
this code (as appropriate) and to the manufacturers' instructions.
9.
Ballasts
Where ballasts are covered by other types of protection combined with
type of protection 's', reference should be made to other Parts of this
code (as appropriate) and to the manufacturers' instructions.
10.
Light Transmitting Parts
Where light transmitting parts are incorporated in apparatus of type of
protection 's', they may only be replaced by parts specified by the
manufacturer or, where possible, repaired, in accordance with the
manufacturers' instructions.
SECfiON THREE- RECLAMATION
In general, few parts of apparatus to type of protection 's' may be reclaimed
except where combined with other types of protection.
1.
EncJosures
Where enclosures of other types of protection combined with type of
protection 's' may be subject to redamation, reference should be made
to the relevant Part(s) of this code.
Where the enclosure is only
type of protection 's', reference should be made to the manufacturer
for advice. No attempt should be made to reclaim (or repair) factory
sealed assemblies.
2.
Cable and Conduit Entries
Where entries of other types of protection combined with type of
protection 's' may be subject to reclamation, reference should be made
to the relevant Part(s) of this code. Where the terminations are only
type of protection 's', reference should be made to the manufacturer
for advice.
7-3
3.
Flame Arrestors
In some cases flame arrestors may be reclaimed by special cleaning
processes specified by the manufacturer. However, after cleaning, the
flameproof or sealed joint between the flame arrestor and its housing
should still comply with the requirements of the certificate.
SECTION FOUR- MODIFICATION
Few parts of type of protection 's' apparatus are amenable to modifications
except when combined with other types of protection.
1.
Enclosures
2.
Entries
3.
Terminations
Where other types of protection are
combined with type of protection 's',
reference should be made to the relevant
Part(s) of this code for instructions
Where type of
relatmg to modifications.
protection 's' only is involved, refer to
the manufacturer.
7-4
PART EIGHT· PROTECI10N BY ENCLOSURE FOR USE
IN THE PRESENCE OF COMBUSTIBLE DUSTS
0.
INTRODUCfiON
This part of the code of practice is intended to complement BS 6467
Part 2 with regard to matters in respect of the repair and overhaul of
apparatus for use in the presence of combustible dusts.
A ]jst of relevant constructional and testing standards containing
spedfic requirements can be found in Annex A (Page v).
This Code of Practice should be read in conjunction with the General
requirement - Part One of this code.
The foundations for safety for this concept are based on:
Protection against ingress of dust
Surface temperatures limitation
Safety factors for the ignitions temperature of both dust
clouds and/or dust layers.
SECfiON ONE· GENERAL
1.
Scope
Thls part of the Code outlines the requirements of the manufacturer,
user and repairer in connection with the repair and overhaul of
electrical apparatus, with protection by enclosure for use in the
presence of combustible dusts.
SpeCial care is to be exercised in the repair and overhaul due to the
nature of the combustible dust and the variety of dusts encountered.
See General Requirements, Page 1·7, Guidance to the User.
SECTION TWO- REP AIR AND OVERHAUL
1.
Enclosure
i)
Whilst it is preferred to obtain new parts from
the manufacturer, in principle damaged parts may
be repaired or replaced with others providing
the enclosure protection is maintained to IP65
or IP55 whichever is applicable.
Particular
attention should be paid to the sealing of the
joints.
Where gaskets are not fitted sealing
compound, suitable for the temperature range of
the enclosure, may be used.
8-1
2.
ii)
Where gaskets are fitted to a joint they must be
free from damage otherwise replacements should
be of the same materials and dimensions as the
origiinal.
Any proposed change of material
should be referred to the apparatus manufacturer
or certification authority.
iii)
The· drilling of holes into an enclosure is a
modification and should not be carried out
without reference to the Standard (BS 6467 Pt 1)
or the manufacturer.
iv)
Before a rewound or repaired rotating machine. is
put back into service, it is essential to ensure
that fan cover ventilation holes are not blocked
or so damaged as to impair the passage of
coolling air over the machine, and that there are
adequate fan clearances in compliance with the
req11irements of the Standard, if appropriate.
Should a fan or fan cover be so damaged as to
require renewal, the replacement parts must be
of 1the same dimension and at least the same
quality as the original parts, and should where
appropriate, take account of the requirements of
the Standard to avoid frictional sparking and
elec;trostatic charging, and the chemical
env1ironment jn which the machine is used.
v)
If drain holes are evident ensure that screwed
plugs are fitted and locked in position.
Cable and Conduit Entries
Entries into the enclosure should conform after repair and overhaul, to
the conditions detailed in the appropriate Standard and/or
certification documents where applicable, preserving the 1P65 or IP55
minimum protection as appropriate.
3.
Shaft/Motor Entry Sealing
Shaft seals have limited life and should be replaced at intervals
recommended by the manufacturer (this interval will depend on
environmental conditions)..
When bearings are replaced, new shaft
seals should be fitted, care being taken during re-assembly, by
protecting against sharp edges.
Thls is not applicable to Labyrinth
seals.
4.
Tenninations
i)
Care should be taken when refurbishing terminal
compartments to maintain clearances and
creepages in accordance with the Standard or
ma1nufacturers practices.
'Where non-metallic
screws are used for fixing then only replacement
screws of similar materials may be used.
8-2
ii)
5.
Where terminations are loose leads the method of
termination, including insulation, should be in
acc{)rdance with the Standards or manufacturers
recommendations.
Jnsulation
A class of insulation the same as or superior to that originally
provided should be employed.
H superior in class to the original,
advantage should not be taken to increase the rating of the winding, as
the temperature c1assification of the apparatus could then be adversely
affected.
6.
Internal Connections
Jntem_al connections may be renewed, given that any in-sulation on such
connections is not electrically, thermally, or mechanically jnferior to
that originally supplied. The cross-sectional area of any replacement
connection should not be less than that originally fitted.
7.
Windings
7.1
General
Where rewinding is carried out, it is essential that the original
winding data are determined and that the new winding conforms to the
original.
The original winding data should preferably be obtained from the
manufacturer; if this is not possible then use may be made of copy
winding techniques.
It is not recommended to have a partial winding replacement, except on
larger apparatus where this may be practicable, unless reference has
been made to the manufacturer or certifying authority.
7.2
Repair of Rotating Machine Rotors
A faulty die cast aluminium rotor should be replaced by a complete new
rotor obtained from the manufacturer or his distributor.
Bar wound cage rotors may be rewound using materials of equivalent
Particular care is necessary to ensure that, if
specification.
replacing conductors in a cage rotor, such- conductors are tight in the
slots. The method of achieving tightness employed by the manufacturer
should be adopted.
7.3
Testing After Repair of Windings
7.3.1
General
Windings, after complete or partial repair should be subjected,
preferably with apparatus assembled, to the following tests so far as
is reasonably practicable:
8-3
a)
The resistance of each winding should be measured at room
temperature and verified.
In the case of three phase
windings the rt!sistance of each phase, or between line
terminals should be balanced.
b)
An insulation
test should be applied to measure the
resistance betwe1en the windings and earth, between windings
where possible, and between auxiliaries and earth.
A
minimum test voltage of 500 volts de is recommended.
Minimum acceptable insulation resistance values are a
function of r~tedl voltage, temperature, type of apparatus and
whether the rewind is partial or complete. However the
insulation resistamce should not be less than 20 megohms, at
20°C, on a completely rewound apparatus intended for use at
up to 650 volts.
7.3.2
c)
A high voltage test in accordance with a relevant Standard
should be applied between windings and earth, between
windings where possible, and between windings and auxiliaries
attached to the windings.
d)
The apparatus should preferably be energised at rated supply
and supply current/secondary voltage measured. The measured
value should be compared with that derived from the
manufacturer's data, where available, and in three-phase
systems should be balanced in all phases.
e)
High voltage (eg lOOOV ac/1500V de and above) and other
special apparatus may require additional tests which should
be agreed with the user or manufacturer.
Rotating Machines
Rotating machines, in addition to the above tests, should be subjected
to the following tests so far as is reasonably practicable:
a)
The machine should be run at full speed and the cause of any
untoward noise :and/or mechanical Vlbration investigated and
corrected.
b)
The stator windi:ngs of cage machines should be energised at
an appropriate reduced voltage, with the rotor locked, to
obtain the full load rated current and to ensure balance on
all phases.
(The test, which in some respects is an
alternative to a fuJI load test, is used to confirm the
integrity of the~ stator winding and its joints and to
indicate the prese:nce of rotor defects).
c)
High voltage (e.g. lOOOV ac/1500V de and above) and non cage
machines may require alternative and/or additional tests
which should be agreed with the user or manufacturer.
Guidance on test voltages and additional tests for rotating
machines is given in BS 4999, Part 143.
7.4
Auxiliary Equipment
If the temperature sensors are included to limit external surface
temperatures, it is recommended that they are embedded into the winding
'b efore varnishing and curing..
The Standard BS 6467 Part 1 suggests that under adverse electrical
conditions temperature semsors should be fitted. In rewinding an
electrical rotating machine: temperature sensors should be fitted if
incorporated in the original winding.
Advice regarding the operating temperature of the sensor .should be
obtained from the manufacturer where possible.
SECITON THREE- RECLAMATION
Reclamation using the techniques detailed in Part One of the code may be used.
1.
Enclosures
Minor damage to enclosures, terminal boxes and covers may be repaired
by welding or metal stitching but care is necessary to ensure that the
integrity of the apparatus is not impaired, in particular, that it
remains capable of withstanding the impact test and maintains the
degree of protection.
2.
Joints
Damaged or corroded joint faces may be machined providing that the
mechankal strength and operation of the component is not impaired and
the degree of protection is not affected.
Spigoted joints are normally provided to achieve close tolerance
location. Thus, matching the male part wilJ require addition of metal
to, and machining of the female part (or vice versa) to retain the
location properties of the joint.
If only one part is damaged, that
part may be restored to its original dimensions by the addition of
metal and re-machining.
The addition of metal may be by
electroplating, sleeving, or welding, but metal spraying by the unfused
method is not generally recommended.
3.
Threaded Holes
Reclamation of damaged threaded holes may be achieved using the
techniques described in Part. One of the code.
4.
Rotating Machines
i)
Shaits and Housings
ShaJfts and bearing housings may be reclaimed,
preferably by use of metaJ spraying or s]eeving
techniques. Welding may be appropriate having
due regard to the limitations of this technique
-Part One of this code.
8-5
ii)
Journals
Journals may be built up by electroplating or
metal spraying.
Rotors and Stators
Rotors and stators may be lightly skimmed to
remove eccentricities and surface damage,
providing that the resultant increased · air gap
between rotor and stator does not result in
4igher internal or external surface temperatures
that infringe the temperature class of the
machine.
Skimmed or damaged stator cores should be
subjected to a "flux test" to ensure that there
are no remaining bot spots which could infringe
the temperature
classification
or
cause
subsequent damage to the stator windings.
SECTION FOUR- MODIFICATIONS
1.
Enclosures
Enclosures may be modified provided that the specified temperature
classification, degree of protection and impact test requirements are
met.
2.
Cable and Conduit Entries
Care should be taken to ensure that the specified type and degree of
protection is maintained.
3.
Terminations
May be modified providing that compJiance with the Standard
maintained.
4.
lS
Windings
i)
It is permissible to rewind apparatus for
another voltage, after reference to the
manufacturer, provided that, for example, the
magnetic loading, current densities and 1osses
are not increased, appropriate new clearances
and creepage distances are observed, and the new
voltage
is within
the limits of
the
certificate.
The rating plate should be
changed to show the new parameters.
ii)
Rewinding a rotating machine for a different
speed is not permissible without reference to
the manufacturer since the electrical and
thermal characteristics of the machine could be
significantly altered so as to take it outside
the limits of the certification documents.
8-6
5.
Auxiliary Equipment
In cases where additional auxiliary equipment is requested, e.g.
anticondensation heaters or temperature sensors, the manufacturer
should be consulted to establish the feasibility of, and the procedure
for, the proposed modification.
See Clause 7.4 of Section Two for notes on temperature sensors.
8-7
BSI Handbook 22- Quality Assurance- contains the following British Standards:
BS.6467
BS.6467
BS.6467
E lectrical apparatus with protection by
enclosure for use: in the presence of
combustible dustsSpecification for apparatus.
Guide to selection, installation and
maintenance.
Glossary of Terms used in Quality
Assurance.
A Guide to Quality Assurance.
Glossary of Terms used in Metrology.
Quality Systems.
Reliability of Systems, Equipments and
Components.
Measurement and Calibration Systems.
Guide to the Determination and Use of
Quality Related Costs.
Pt.l
Pt.2
BS.4778
BS.4891
BS.5233
BS.5750
BS.5760
BS.5781
BS.6143
BASEEFA SFA3009:
BASEEFA SFA.3012:
BASE~FAEx-MEMO
No.1-
Type of Pro.tection Ex 's'.
Type of Protection Ex 'i'.
Explanatory Mem.orandum on marking and
labelling of certified apparatus and
components as used in the UK.
Note: Additional relevant Standards are listed
in BS.5345 : Part 1
vi
Contract requirements: This Code of Practice does not purport to
include all the necessary provisions of a contract.
Users of this
Code of Practice are responsible for its correct application.
Revisions: This Code of Practice will be revised when necessary, by
the issue either of amendments or of revised eclitions.
It is
important that users of the Code of Practice ascertain that they are in
possession of the latest amendments or edition.
PARTICIPATING ORGANISATIONS
ENGINEERING EQUIPMENT MATERIALS USERS' ASSOCIATION
INSTITUTE OF PETROLEUM
AMENDMENTS:
Revision 1 incorporates Amendments 1, 2 & 3
AMENDMENT NUMBER
DATE OF ISSUE
4 (Correction of
typographical error)
TEXT AFFECTED
7.3.1 b). Para 2.
200 megohms to read
20 megohms.
~~
Further copjes are available from:
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Telephone: 0171-793 3000 Telefax: 0171 -793 3003
Association of Electrical and Mechanical Trades,
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Vll
BEAMA LIMITED
BEAMA js the Federation of British Electrotechnjcal and Allied
Manufacturers• Associations. Eighteen federated Associations represent
between them some 570 com~anies.
A wide range of electrical products is covered including:Turbo-generating equipment, transformers and switchgear;
metering
equipment, rotating electrical machines, installation equipment including
circuit-breakers, conduit, plugs, sockets, wiring accessories, switches
and controls; and power supplies.
Laboratory,
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and
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Advanced and traditional electric road vehicles;
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The AEMT is :recognised as the Association in UK which represents the
electrical repair and merchanting industry. It has more than 150 member
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