Offshore Transformer Platform
Technical Standard
Energinet.dk
HV, MV, LV and Signal Cables and
Cable Routing
ETS - 03
Rev. 1
Acadre doc. 44858-09
Revision survey
Chpt.
-
Description
1st edition and revision
Appendix no. and description
Revision
Date
Resp.
1
12-10-09
SGH
Revision
None
ETS - 03 Rev. 1
Table of contents
1.
Scope
1
2.
References
2.1
Statutory Regulations
2.2
Codes and Standards
1
1
1
3.
Definitions
3.1
Definitions
2
2
4.
Technical Requirements
4.1
General
4.1.1 Requirements
4.1.2 Cable segregation
4.1.3 Cable ladders and trays
4.1.4 Cable installation
4.1.5 Cable pulling force and bending radius
4.1.6 Cable cleating and strapping
4.1.7 Cable splicing
4.1.8 Temporary cables
4.1.9 Cable gland selection
4.1.10
Termination
4.1.11
Spare conductors
4.1.12
Marking
4.2
HV cables
4.2.1 Specification
4.2.2 Selection
4.3
MV cables
4.3.1 Specification
4.3.2 Selection
4.4
LV cables
4.4.1 Specification Power supply cable
4.4.2 Selection
4.5
Signal cables
4.5.1 Specification for category 5e cables
4.5.2 Specification for coax cables
4.5.3 Specification for optical fibre cables
4.5.4 Specification for twisted pair cables
4.5.5 Selection
3
3
3
3
3
4
4
4
5
5
5
5
6
6
7
7
7
8
8
8
10
10
11
11
12
12
12
12
13
5.
Certificates / Data books
13
6.
Appendix
13
ETS - 03 Rev. 1
1.
Scope
This technical standard specifies the basic requirements for the High, Medium and
Low Voltage and signal cables to be used on an offshore located transformer
platform for offshore wind farms established in the Danish offshore sector.
Further the installation, segregation and support of cables is described in general
terms.
2.
References
2.1
Statutory Regulations
2.2
•
Energi Styrelsen
•
•
Direktiv 2006/95/EF
BEK nr. 27 af 10/01/2007
RETNINGSLINIER FOR DESIGN AF FASTE
OFSHOREANLÆG
Lavspændingsdirektivet
Bekendtgørelse om radio-og teleterminaludstyr
og elektromagnetiske forhold
(EMC Direktiv 2004/108/EF)
Codes and Standards
•
•
ANSI/TIA 568B
EN 50167
•
•
EN 50173
IEC 11801
•
•
•
•
•
•
•
IEC
IEC
IEC
IEC
IEC
IEC
IEC
•
•
IEC 60364
IEC 60724
•
IEC 60754
60038
60092
60183
60287
60228
60331
60332
Communications cabling standard
Sectional specification for horizontal floor wiring cables
with a common overall screen for use in digital
communication
Information technology – Generic cabling systems
Information technology – Generic cabling for customer
premises
IEC standard voltages
Electrical installations in ships
Guide to the selection of high-voltage cables
Electric cables – Calculating of the current rating
Conductors of insulated cables
Tests for electrical cables under fire conditions
Tests on electric and optical fibre cables under fire
conditions
Low-voltage electrical installations
Short-circuit temperature limits of electric cables with
rated voltages from of 1 kV (Um=1,2 kV) and up to 3 kV
(Um=3,6 kV)
Test on gasses evolved during combustion of electric
cables
ETS - 03 Rev. 1
1
•
•
•
IEC 60793
IEC 60794
IEC 60840
•
•
IEC 60885
IEC 60949
•
IEC 60986
•
•
IEC 61034
IEC 61034
•
IEC 61443
•
•
IEC 61892
IEC/TR 62095
3.
Definitions
3.1
Definitions
Optical fibres
Optical fibre cables
Power cables with extruded insulation and their
accessories for rated voltages above 30 kV (Um= 36 kV)
up to 150 kV (Um=170 kV) – Test methods and
requirements
Electrical test methods for electrical cables
Calculation of thermally permissible short-circuit
currents, taking into account non-adiabatic heating
effects
Short-circuit temperature limits of electric cables with
rated voltages from of 6 kV (Um=7,2 kV) and up to 30 kV
(Um=36 kV)
Measurement of smoke density of cables burning under
Measurement of smoke density of cables burning under
defined conditions
Short-circuit temperature limits of electric cables with
rated voltages above 30 kV (Um=36 kV)
Mobile and fixed offshore units – Electrical installations
Electric cables – Calculation for current ratings – Finite
element method
•
Shall:
Verbal form used to indicate requirements to be strictly
followed in order to conform to the standard and from
which no deviation is permitted, unless accepted by all
parties.
•
Should:
Verbal form used to indicate that among several
possibilities one is recommended as particularly suitable,
without mentioning or excluding others, or that a certain
course of action is preferred but not necessarily required.
•
May:
Verbal form used to indicate a course of action
permissible within the limits of the standard.
•
Can:
Verbal form used for statements of possibility and
capability, whether material, physical or casual
ETS - 03 Rev. 1
2
4.
Technical Requirements
4.1
General
4.1.1
Requirements
Cables shall comply with the relevant standards applicable for the particular use of
the cable.
All cables used shall be minimum flame retardant (IEC 60332). Fire resistant cables
shall be used for essential services such as fire detection and alarming and
emergency lighting.
Generally all cables should have a tinned copper braid armouring and an outer
sheath which is UV resistant. Cables without armour may be used in staff rooms and
in control equipment rooms.
4.1.2
Cable segregation
Signal cables shall be routed separate from HV, MV and LV cables. Minimum distance
should be 600mm to HV and MV cables and 300mm to LV cables. Instrument cables
and communication cables can generally be routed together.
Signal cables crossing at a right angel with LV cables is acceptable without further
segregation.
High voltage cables shall in the full length be separated from medium voltage and
low voltage cables by at least 300 mm unless mechanically separated by earthed
metal partitions or pipes.
Medium voltage cables shall in the full length be separated from High voltage and
low voltage cables by at least 300 mm unless mechanically separated by earthed
metal partitions or pipes.
Considerations must be taken during installations of cables entering and leaving
equipment like power transformers, crane etc. related to the requirements of
segregation.
4.1.3
Cable ladders and trays
All cables should be routed on cable ladders, cable trays and/or J-tubes.
Outdoor cable ladders and trays shall be fibre reinforced plastic.
Indoor cable ladders and trays may be galvanized steel.
Conduits may be used for special mechanical protection of single field routed cables
for shorter distances.
ETS - 03 Rev. 1
3
The cable ladders and trays should not be filled so the height of their side rail is
exceeded. Further the ladders and trays should not be filled beyond 50% of their
total capacity.
Redundant cable systems shall as far as possible be routed separately.
MV cables should be routed and grouped depending of the chosen current carrying
capacity estimation method, according to section 4.3.2.
4.1.4
Cable installation
Access for maintenance and an orderly layout shall be ensured when cabling below
raised floor is performed.
Once a cable has been cut, a protective cap/sealing shall be applied on the end,
when being exposed to humid atmosphere.
All cable entries to equipment located outdoor and in deluge covered areas should be
from below. Top entry is not allowed and side entry shall be provided with additional
protection against ingress of moisture.
Sufficient cable spare length shall be provided for equipment which needs future
adjustments (floodlights, loudspeakers, TV cameras etc.) or where equipment have
to be dismounted for maintenance and calibration without disconnecting the cable.
Single core cables for three-phase AC shall run in trefoil formation. The braided
armour shall be earthed in one end only.
Single core cables shall not be installed separately through openings surrounded by
magnetic materials. Non-magnetic stainless steel separation walls and stay plates
shall be used in cable transits used for single core cables.
4.1.5
Cable pulling force and bending radius
The maximum pulling force and minimum permissible bending radius specified by
supplier shall be adhered to.
4.1.6
Cable cleating and strapping
All cables shall be fixed properly to the cable support systems.
Plastic coated stainless steel straps shall be used for all cable runs outside and in non
ventilated areas.
UV resistant nylon straps may be used in indoor and ventilated locations.
The Plastic coated stainless steel straps shall be used for vertical runs and for
horizontal runs in the vertical plane both indoor and outdoor. For strapping of fibreoptical and coaxial cables, supplier guidelines shall be adhered to.
ETS - 03 Rev. 1
4
The distance between cable straps shall not exceed:
•
•
•
600mm for horizontal runs
300mm for vertical runs and for horizontal runs in the vertical plane
Ten times the cable outer diameter from cable entry to the first strap
Single core power cables for three-phase AC shall be fixed with trefoil cable cleats
which shall be approved for the potential short circuit stress. The cleats shall
outdoors, in naturally ventilated areas and deluge covered areas be made of
stainless steel.
The distance between trefoil cleats shall be as specified by the cable manufacturer
based on the calculated short circuit level. The distance shall be selected such that
the cable will not be damaged by a possible short circuit. Normal distance is 300mm,
and on every step on bends and risers.
4.1.7
Cable splicing
Cable splicing should be avoided.
If splicing seems unavoidable it shall be agreed with “Energinet.dk” for the
installation in question.
4.1.8
Temporary cables
Temporary cables routed on permanent cable support systems shall be installed such
that they will not obstruct permanent installations and are easy to remove.
4.1.9
Cable gland selection
Cable glands, bushings, modular multi cable transits (MCT) or fittings for screwed
conduits, shall be provided according to the way in which the cables enter the
equipment or rooms. All entries shall maintain the degree of protection provided by
the enclosure of the associated equipment or room. These shall apply to the whole
range of cable dimensions specified by the manufacturer of the cable entries as
suitable for use with those entries.
Bottom entry is preferred for outdoor or deluge protected areas. Side entry is
acceptable by use of drip nose installation for the cable in question.
Types, maximum numbers and positions of Cable glands and blanking element
entries for mounting in electrical apparatus for installation in explosive gas
atmospheres shall be specified in a document submitted by the manufacturer.
Shrouds and similar shall not be used on cable glands.
4.1.10
Termination
All cable conductors shall be terminated by use of compression lugs or ferrules
dependent upon the type of termination. The compression ferrule should be the type
ETS - 03 Rev. 1
5
where the conductor strands are inserted through the whole ferrule and reach the
bottom of the terminal.
Support for cleating of cables when entering the panels should be provided.
In switchboards and distribution boards adequate space shall be provided for the use
of a clip-on ampere meter without causing undue stress on the cable conductors or
connections.
The braid armour and the screen shall be separated from each other as well as from
the conductors, twisted and fitted as required. This shall be done without any
reduction of the cross sectional area.
Where the screen shall be left disconnected, which is applicable for field instruments,
it shall be sealed and isolated with an isolating cap, allowing for insulation testing
without any disconnecting.
Only one conductor is allowed in each terminal of a terminal block/row for external
connections. This is not related to terminals as integrated part of internal
components (e.g. relays and contactors) of the equipment. Two conductors may in
certain cases be used in one approved type ferrule connected to one terminal.
4.1.11
Spare conductors
Spare conductors in instrument and telecom cables shall be terminated at the
cabinet end and left floating at the field end.
In cabinets all spare conductors shall be marked with terminal number and
connected to terminals linked together by solid terminal links, which shall be
connected to the relevant earth bar.
Spare cores in instrument and telecom cables shall be connected to instrument earth
in supply end only.
If there are no spare terminals left in the cabinet, all spare conductors shall be
covered with yellow/green sleeves and marked with relevant cable number and
connected directly to the relevant earth bar.
4.1.12
Marking
Numbering of cables shall be in accordance to the relevant document standard for
the platform.
Each cable shall be marked with indelible and non-corrosive cable markers indicating
the cable number. The cable markers shall be clearly visible after cleating and
strapping. Outdoors, in exposed- and deluge covered areas the cable markers should
be made of stainless steel.
Each cable shall have a cable marker located:
ETS - 03 Rev. 1
6
•
•
•
•
4.2
At both sides of cable transits
At both ends
Outside cabinets with gland entries
Inside cabinets with open entries
HV cables
The designation “High Voltage cables (HV cables)” applies to submarine cables in
a.c. three-phase systems having a nominal voltage above 35 kV and not
exceeding 250 kV.
The characteristics of the High Voltage range is specified according to IEC
60038, IEC standard voltages.
4.2.1
Specification
The cable shall be three-core submarine cable with conductors made of copper. The
insulation shall be dry extruded (XLPE) and longitudinally watertight. The sheat shall
be made of lead or lead alloy. The cable shall be armoured with additional external
corrosion protection capable of resisting forces acting on the cable during laying,
embedding and possible repair. the armouring shall be applied in a continuous
process.
The cable shall have integrated optical fibres.
4.2.2
Selection
A guidance for the selection of the cable conductor size, cable insulation level and
cable construction is given according to IEC 60183.
The lightning overvoltage of the cable must comply with the defined lightning
protection zones and the effects of the installed lightning protection provisions.
The choice of cables of appropriate cross-sectional area of conductors and current
carrying capacity should be estimated according to information given in IEC 60287
and IEC/TR 62095.
The selected cables and their insulated conductors shall be capable of
withstanding the mechanical and thermal effects of the maximum short circuit
current which can flow in any part of the circuit in which they are installed,
taking into consideration not only the time/current characteristics of the circuit
protective device, but also the peak value of the prospective short circuit
current during the first half cycle.
The cable short-circuit current withstand capability should be evaluated
according to information given in IEC 61443 and IEC 60949.
New and modified cable installations should be electrically tested as specified
according to IEC 60840.
ETS - 03 Rev. 1
7
4.3
MV cables
The designation “Medium Voltage cables (MV cables)” applies to cables for fixed
installations in all installations, whether permanent, temporary, transportable or
hand-held, to a.c. three-phase systems having a nominal voltage above 1 kV
and not exceeding 35 kV.
The characteristics of the Medium Voltage range is specified according to IEC
60038, IEC standard voltages.
4.3.1
Specification
Cables constructed in accordance with IEC 60092-350, IEC 60092-353, IEC
60092-354 and IEC 60092-376 are recommended for use as MV cables on fixed
offshore units.
4.3.2
Selection
The selection of the standard MV cable characteristics and type is based on the
actual nominal system voltage and the demanded current carrying capacity.
The choice of standard cables of appropriate voltage designations for particular
systems depends upon the system voltage and the system earthing arrangements.
A guidance for the selection of the cable conductor size, cable insulation level and
cable construction is given according to IEC 60183.
The rated voltage of any cable shall not be lower than the nominal voltage of the
circuit for which it is used. To facilitate the choice of the cable, the values of U
recommended for cables to be used in three-phase systems are listed in Table 1 in
which systems are divided into the following three categories, A, B and C.
Category A
This category comprises those systems in which any phase conductor that
comes in contact with earth or an earth conductor is automatically disconnected
from the system.
Category B
This category comprises those systems that, under fault conditions are operated
for a short time, not exceeding 8 hours on any occasion, with one phase
earthed.
Category C
ETS - 03 Rev. 1
8
This category comprises all systems that do not fall into Categories A and B.
Table 1 - Choice of cables for a.c. systems
System
Category
System voltage
Nominal
voltage
U
kV
Maximum
sustained
voltage,
Um
kV
Minimum rated voltage
of cable U0/U
Unscreened
kV
3
3,6
A or B
3
3,6
C
3,6 / 6,0
6
7,2
A or B
3,6 / 6,0
6
7,2
C
6,0/10
A or B
6,0/10
10
12
1,8/3,0
Single-core or
screened
kV
1,8/3,0
10
12
C
8,7 / 15
15
17,5
A or B
8,7 / 15
15
17,5
C
12 /20
20
24
A or B
12 / 20
20
24
C
18 / 30
30
36
A or B
18 / 30
30
36
C
NA
35
45
A or B
NA
35
45
C
NA
The lightning overvoltage of the cable must comply with the defined lightning
protection zones and the effects of the installed lightning protection provisions.
The choice of standard cables of appropriate cross-sectional area of conductors and
current carrying capacity should be estimated according to one of the following
methods:
- As described according to IEC 60287
- By calculation using a recognized method provided that the method is stated
- According to IEC 61892-4, Annex A
- According to IEC 61892-4, Annex B
ETS - 03 Rev. 1
9
The estimated current carrying capacity should be modified with the adequate
correction factors for different ambient air temperatures, according to IEC 61892-4,
clause 4.3.4.
The selected cables and their insulated conductors shall be capable of
withstanding the mechanical and thermal effects of the maximum short circuit
current which can flow in any part of the circuit in which they are installed,
taking into consideration not only the time/current characteristics of the circuit
protective device, but also the peak value of the prospective short circuit
current during the first half cycle.
The cable short-circuit current withstand capability should be evaluated
according to information given in IEC 60724, IEC 60986 and IEC 60949.
New and modified cable installations should be electrically tested as specified
according to IEC 60885.
4.4
LV cables
The following specified LV cables are intended for use in power supply to installations
such as lighting, socket outlets, heaters, panels etc. Same cables shall be used
whether AC or DC power.
4.4.1
Specification Power supply cable
With the exception of single core cables, all power supply cables from switch gear to
consumers shall have an integral dedicated green/yellow earth wire.
Cable design for non-essential services should be:
Conductor:
Stranded bare copper
Insulation:
Cross linked polyethylene (XLPE)
Inner covering:
Halogen free filler (i.e. polyolefin)
Armouring:
Copper braid (Tinned)
Outer sheath:
Polyolefin
Cable design for essential services should be:
Conductor:
Stranded tinned copper
Insulation:
Mica tape and XLPE
ETS - 03 Rev. 1
10
4.4.2
Inner covering:
Polyolefin
Armouring:
Tinned copper braid
Outer sheath:
Polyolefin
Selection
LV cable types shall be selected to meet the requirements specified according to
IEC 60092-352, Clause 3.1.
All cables or insulated wiring shall meet the requirements for flame spread as
specified according to IEC 60092-352, Clause 3.14.
The cable voltage rating shall comply with the requirements specified according to
IEC 60092-352, Clause 3.2.
Cable cross-sectional areas and current carrying capacity of conductors shall comply
with the requirements specified according to IEC 60092-352, Clause 3.3.
Cable current ratings for continuous service shall, according to IEC 60092-352,
Clause 3.3.3, be selected from Annex B, Tabulated Current Carrying Capacities –
General Installations.
The conductor current carrying capacity of parallel connections of single core cables
or multi core cables shall comply with the requirements specified according to IEC
60092-352, Clause 3.6.
Cables and their insulated conductors shall be capable of withstanding the
mechanical and thermal effects of the maximum short circuit current which can flow
in any part of the circuit in which they are installed, taking into consideration not
only the time/current characteristics of the circuit protective device, but also the
peak value of the prospective short circuit current during the first half cycle. Further
information is given in IEC 60949 and IEC 60724.
Cables for essential/emergency power supply shall fulfil the requirements of IEC
60331.
4.5
Signal cables
The following systems shall have their own dedicated cables:
•
•
•
Digital communication (category 5e, optical fibre and coax)
Fire detection and alarming (Twisted pairs)
Equipment monitoring and alarm (Twisted pairs)
The detailed specifications in the following sections should be regarded as
recommendations. Other cable specifications may be used provided accepted by
Energinet.dk
ETS - 03 Rev. 1
11
4.5.1
4.5.2
4.5.3
Specification for category 5e cables
Category 5e communication cables should be standard twisted 4 pair 100 MHz
manufactured in accordance with ANSI/TIA 568B.
Conductor:
Bare copper (D. 0.52mm)
Conductor insulation:
Polyethylene, PE
Collective screen:
Aluminium/polyester tape with tinned copper drain
wire and tinned copper braid
Outer sheath:
Orange Polyolefin
Specification for coax cables
Coax cables should be standard 50 ohms.
Conductor:
Bare copper-stranded 7 x 0.75mm
Dielectric:
Solid polyethylene Ø7.24mm
Inner screening:
Bare/tinned copper braid
Inner jacket:
Halogen free compound (outer sheath if used inside)
Armouring:
Tinned copper braid (applicable for outdoor use)
Outer Sheath:
Halogen free compound (applicable for outdoor use)
Specification for optical fibre cables
Optical fibre cables should be carefully chosen for the particular use.
Preferably patch cables shall be used for indoor connections between panels.
4.5.4
Specification for twisted pair cables
Twisted pair cables should normally be with common screen unless the particular
installation require individual screen.
Conductor:
Stranded bare copper (Ø 0.75mm2) Twisted in pairs
Insulation:
Cross linked polyethylene, XLPE
Collective screen:
Aluminium/polyester tape with tinned copper drain
wire and tinned copper braid
Armouring:
Tinned copper braid
Outer sheath:
Polyolefin
ETS - 03 Rev. 1
12
4.5.5
Selection
The Category 5e cable should be used for all communication which is not fibre based.
This cable should be for indoor use only, if used outdoor it shall be protected from
the sun and from mechanical damage.
The coax cable should be used for the transmission of signals from control panel to
VDU, and for radio transmission via externally fixed antennas.
The optical fibre cable should be used for most other communication. It shall be
noted that the optical fibre for communication to shore will be integrated in the main
150kV power cable to shore.
5.
Certificates / Data books
NA.
6.
Appendix
NA.
ETS - 03 Rev. 1
13