NZQA registered unit standard
28887 version 1
Page 1 of 4
Title
Demonstrate knowledge of disconnectors and earth switches used in
substations
Level
4
Credits
7
Purpose
People credited with this unit standard are able to demonstrate
knowledge of: types of disconnectors and earth switches;
operating principles for disconnectors and earth switches;
testing and maintenance requirements for disconnectors and
earth switches; and condition assessment of disconnectors and
earth switches.
Classification
Electricity Supply > Electricity Supply - Power System
Maintenance
Available grade
Achieved
Explanatory notes
1
This unit standard is intended for assessment off-job. The range statements and
evidence requirements across the unit standard can be applied according to industry
specific equipment, procedures, and processes as applied in the electricity supply
industry.
2
Performance and work practices in relation to the outcomes and evidence
requirements must comply with all current legislation, especially the Electricity Act
1992 and any subsequent amendments, any regulations, codes of practice
recognised under that statute; Health and Safety in Employment Act 1992 and any
subsequent amendments; Resource Management Act 1991 and any subsequent
amendments; electricity supply industry codes of practice; and documented
enterprise procedures. These include the latest version of Safety Manual –
Electricity Industry (SM-EI) Wellington: Electricity Engineers’ Association.
A full list of current legislation and industry codes is available from:
Infrastructure Industry Training Organisation
PO Box 1245
Hamilton 3240.
3
The phrase in accordance with industry requirements is implicit in all outcomes and
evidence requirements in this unit standard.
4
Definitions
Asset owner refers to the owner of an electricity supply network that takes its point of
supply from Transpower NZ, and delivers electricity to industrial, commercial and
residential customers.
Infrastructure ITO
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
28887 version 1
Page 2 of 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 in which assessment is carried out.
Outcomes and evidence requirements
Outcome 1
Demonstrate knowledge of types of disconnectors and earth switches.
Evidence requirements
1.1
Commonly used disconnector and earth switches are identified.
1.2
Function of disconnectors and earth switches are described.
1.3
Location of disconnectors and earth switches is explained.
Outcome 2
Demonstrate knowledge of operating principles for disconnectors and earth switches.
Evidence requirements
2.1
Contact arrangements are described.
Range
2.2
Configuration arrangements are described.
Range
2.3
may include but is not limited to: single break, double break,
centre side break, single vertical break, pantograph, overhead,
under hung.
Evidence of three configuration arrangements is required.
Operating arrangements are described.
Range
2.4
may include but is not limited to: beavertail, wedge, high pressure
plate and sphere, loop and jaw, jaw and blade, scissor and
trapeze.
Evidence of three contact arrangements is required.
may include but is not limited to: lever type operating handle,
pump type operating handle, hand-wheel type, crank type, motor
drive.
Evidence of two operating arrangements is required.
Contact requirements are described.
Range
Infrastructure ITO
SSB Code 101813
contact pressure, alignment, lubrication, contact materials.
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
2.5
Operating mechanisms are described.
Range
2.6
28887 version 1
Page 3 of 4
includes but is not limited to: linkages, motor drives and controls,
mechanical and electrical interlocks, auxiliary contacts, timing and
synchronisation.
Arc extinction process for disconnectors is explained.
Outcome 3
Demonstrate knowledge of testing and maintenance requirements for disconnectors and
earth switches.
Evidence requirements
3.1
Testing requirements for disconnectors and earth switches are described.
Range
3.2
includes but is not limited to: functional checks, contact resistance
measurement, diagnostic inspection and service.
Maintenance requirements are described.
Range
includes but is not limited to: corrosion, contacts, operating
mechanisms, bolts, insulators, earthing, contact and insulation
tests, operational adjustments.
Outcome 4
Demonstrate knowledge of condition coding assessment of disconnectors and earth
switches.
Evidence requirements
4.1
Condition coding is described for disconnectors and earth switches.
Planned review date
31 December 2020
Status information and last date for assessment for superseded versions
Process
Version Date
Last Date for Assessment
Registration
1
17 March 2016
N/A
Consent and Moderation Requirements (CMR) reference
0120
This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Infrastructure ITO
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
28887 version 1
Page 4 of 4
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA,
before they can report credits from assessment against unit standards or deliver courses
of study leading to that assessment.
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and
which are assessing against unit standards must engage with the moderation system that
applies to those standards.
Requirements for consent to assess and an outline of the moderation system that applies
to this standard are outlined in the Consent and Moderation Requirements (CMR). The
CMR 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 Infrastructure Industry Training Organisation at
qualifications@infrastructureito.org.nz if you wish to suggest changes to the content of this
unit standard.
Infrastructure ITO
SSB Code 101813
 New Zealand Qualifications Authority 2016