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Carry out routine inspection and servicing on high voltage gas
insulated switchgear
Level
4
Credits
5
Purpose
People credited with this unit standard are able to: prepare for inspection,
testing and servicing on high voltage gas insulated switchgear (GIS); make
the circuit breakers safe for work; carry out routine inspections and diagnostic
tests; carry out servicing; perform function tests and pre-service checks; and
complete documentation.
Subfield
Electricity Supply
Domain
Electricity Supply - Power System Maintenance
Status
Registered
Status date
27 April 1998
Date version published
21 November 2008
Planned review date
31 December 2009
Entry information
Prerequisites: Unit 14287, Use and maintain test
instruments used within the high voltage electrical
industry; Unit 14700, Apply and remove safety measures
in an electricity supply environment; Unit 14701, Manage
electricity supply work control systems; Unit 12296,
Apply earths to and remove earths from electrical
conductors, plant and equipment; or demonstrate
equivalent knowledge and skills.
Accreditation
Evaluation of documentation and visit by NZQA and
industry.
Standard setting body (SSB)
Electricity Supply Industry Training Organisation
Accreditation and Moderation Action Plan (AMAP) reference
0120
This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Special notes
1
This unit standard can be assessed against in a workplace environment, or in a
training or educational environment if simulated equipment response and examples
are able to be provided, or in a combination of both environments.
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2
Performance and work practices in relation to the elements and performance criteria
must comply with all current legislation, especially the Electricity Act 1992, and any
regulations and codes of practice recognised under that statute; the Health and
Safety in Employment Act 1992; and the Resource Management Act 1991.
Electricity supply industry codes of practice and documented industry procedures
include the Safety Manual – Electricity Industry (SM-EI) (2004) Wellington: Electricity
Engineers’ Association. A full list of current legislation and industry codes is
available from the Electricity Supply Industry Training Organisation, PO Box 1245,
Hamilton 3240.
3
The phrase in accordance with industry requirements is implicit in all elements and
performance criteria in this unit standard.
4
Industry requirements include all asset owner requirements; manufacturers’
specifications; and enterprise requirements which cover the documented workplace
policies, procedures, specifications, business, and quality management requirements
relevant to the workplace, or training or educational environment in which
assessment is carried out.
5
Core electrical theory is essential knowledge underpinning the performances
required by this unit standard.
6
The range of this unit standard is limited to carrying out diagnostic testing and
applying preventative maintenance and replacement repairs, where necessary, on
high voltage GIS circuit breakers, and is normally done at electricity supply
substations and power stations.
7
The following terms and abbreviations relate to this unit standard:
GIS refers to Gas insulated switchgear
CB refers to Circuit breaker
SF6 refers to Sulphur Hexafloride Gas
HV refers to High voltage
PPMV refers to Parts per million/volume
PPMW refers to Parts per million/weight
IEC refers to International Electrotechnical Commission
Elements and performance criteria
Element 1
Prepare for inspection, testing and servicing on high voltage gas insulated switchgear
(GIS).
Performance criteria
1.1
The scope of work and equipment to be serviced is identified from client
requirements.
Range
may include but is not limited to – associated check and/or
inspection lists, procedures and client required diagnostic tests
and servicing for – GIS circuit breakers with hydraulic, pneumatic
or motor-spring mechanisms.
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1.2
Personnel and equipment are resourced for the required work.
Range
1.3
The inspection, diagnostic testing and servicing requirements are interpreted
and analysed for determining the performance and quality standards required.
Range
1.4
may include but is not limited to – people, tools, spares, materials,
‘inspection sheets’, procedure sheets.
may include but is not limited to – manufacturer’s guidelines, client
maintenance standards, enterprise guidelines.
The construction of GIS equipment is described and explained, consistent with
maker’s manuals.
Range
may include but is not limited to – solid material and gas
insulation, operating methods, nature of SF6 tests required, typical
values, differential pressures, barrier strengths, effect of vacuum
on electrical strengths, ‘Pachons Law’.
Element 2
Make the circuit breakers safe for work.
Performance criteria
2.1
The required access permit, or recognised equivalent, is received, checked, and
signed.
Range
2.2
Additional isolation from other energy sources on the circuit breaker is applied.
Range
2.3
includes a careful check of the isolations to ensure the access
permit or recognised equivalent provides a safe work environment.
may include but is not limited to – removal and draining of high
pressure air, releasing or spragging spring closing energy
systems, isolating actuating trip coils and motor drive systems.
The work party is fully briefed on the equipment to be worked on, work to be
done, safe working zone and safety features in place, and has signed the
access permit or its approved equivalent. All communication with the work
party is clear and unambiguous.
Range
may include but is not limited to the ability to resolve any concerns
the work party may have over the isolations and the delineation of
the safe work area.
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2.4
Safety measures are available and prepared to protect the environment and
personnel.
Range
may include but is not limited to – protective clothing, storage for
gas, breathing filters, safe work area has been identified and
marked.
Element 3
Carry out routine inspections and diagnostic tests.
Performance criteria
3.1
The CB defect history and operational records are scrutinised, and incidents
indicating service needs noted for attention during the routine servicing.
Range
3.2
The inspections carried out identify any damage or defects.
Range
3.3
may include but is not limited to – gas decomposition, relationship
between dew point ppmv and ppmw, temperature, typical values,
IEC 1634:1995.
The diagnostic tests are carried out and the results analysed for interpreting the
servicing required.
Range
3.5
may include but is not limited to – SF6 gas leaks, signs of
overheating, corrosion, porcelain damage.
The SF6 gas tests required are identified and test requirements, including
accepted values, are explained.
Range
3.4
may include but is not limited to – thermovision test results,
malfunctions, reported problems, SF6 gas leaks.
may include but is not limited to – insulation tests, time travel,
contact resistance, timing tests, minimum operating voltage,
alarm, hydraulic and pneumatic pressure settings, moisture in gas,
gas leak detection, external connections, gas quality tests, HV
tests, low pressure lock out settings, hydraulic accumulator
recharge pressure.
The results of the diagnostic tests are recorded to meet the client requirements.
Range
may include but is not limited to – completing enterprise check
lists, electronic data records, client reports.
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Element 4
Carry out servicing.
Performance criteria
4.1
Gas recovery and treatment is completed consistent with enterprise or client
requirements.
Range
4.2
The major or minor invasive servicing is carried out.
Range
4.3
may include but is not limited to storage treatment and re-testing
before re-filling the circuit breakers.
may include but is not limited to – replacement of worn parts,
cleaning, ceramic insulators cleaned, mechanism lubrication,
operation adjustments, corrosion corrective work, SF6 filtering and
top-up, bus section barriers cleaned, gas filter desiccant replaced,
cleaning of bus and switching chambers, visual inspection of
components, unacceptable wear or damage, cleaning solvents.
The re-assembly of the circuit breaker is carried out in the approved manner
provided by the maker.
Range
may include but is not limited to – all components being
assembled in the correct order, with proper fit and secured in the
specified way through inspection to ensure all tools and cleaning
materials are removed from the chamber, gas replaced into circuit
breaker to correct pressure and within permitted moisture
parameters.
Element 5
Perform function tests and pre-service checks.
Performance criteria
5.1
Work party is advised of a trial operation about to start.
5.2
All services and necessary control features are reinstated and approval
obtained for function tests.
Range
5.3
may include but is not limited to – air service, control circuits,
mechanism, power and indication.
All the function tests required are completed without malfunction and to
standard.
Range
may include but is not limited to – gas decomposition, relationship
between dew point ppmv and ppmw, temperature, typical values.
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5.4
All the maintenance tools and facilities have been removed and the circuit
breaker left in the ‘ready-for-service’ condition.
Range
5.5
All equipment worked on is inspected and set for return to service.
Range
5.6
may include but is not limited to – checking all tools removed, all
connections tight, all panels returned, service and/or maintenance
disable switch in correct position, CB returned to service.
may include but is not limited to – confirming all equipment and the
work party are clear, all operational equipment which has been
worked on is now set ready for service.
Return of access permit, or its equivalent, is confirmed.
Range
may include but is not limited to – confirming all members of the
work party have signed off, the equipment is returned to service
without incident.
Element 6
Complete documentation.
Performance criteria
6.1
The ‘as found’ and ‘as left’ conditions are recorded in the plant history.
Range
6.2
The equipment condition status is recorded.
Range
6.3
may include but is not limited to – analysis and reporting of any
defects, correct completion of the plant and defect history,
including replacement spare fitted.
may include but is not limited to – operation counter noted,
number of trial operations noted, pressures and auxiliary service
quantified.
The routine and inspection service records are completed to meet the client
requirements.
Range
may include but is not limited to – written records or electronic
data reporting.
Please note
Providers must be accredited by NZQA, or an inter-institutional body with delegated
authority for quality assurance, before they can report credits from assessment against
unit standards or deliver courses of study leading to that assessment.
Industry Training Organisations must be accredited by NZQA before they can register
credits from assessment against unit standards.
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Accredited providers and Industry Training Organisations assessing against unit standards
must engage with the moderation system that applies to those standards.
Accreditation requirements and an outline of the moderation system that applies to this
standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The
AMAP also includes useful information about special requirements for organisations
wishing to develop education and training programmes, such as minimum qualifications for
tutors and assessors, and special resource requirements.
Comments on this unit standard
Please contact the Electricity Supply Industry Training Organisation info@esito.org.nz if
you wish to suggest changes to the content of this unit standard.
 New Zealand Qualifications Authority 2016