28887 Demonstrate Knowledge of Disconnectors and Earth Switches Used in Substations

Explanatory notes

1This 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.

2Performance 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 ofSafety 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.

3The phrase in accordance with industry requirements is implicit in all outcomes and evidence requirements in this unit standard.

4Definitions

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.

Industryrequirementsinclude 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

1.1Commonly used disconnector and earth switches are identified.

1.2Function of disconnectors and earth switches are described.

1.3Location of disconnectors and earth switches is explained.

Outcome 2

Demonstrate knowledge of operating principles for disconnectors and earthswitches.

Evidence requirements

2.1 Contact arrangements are described.

Rangemay include but is not limited to: beavertail, wedge, high pressureplate and sphere, loop and jaw, jaw and blade, scissor and trapeze.

Evidence of three contact arrangements is required.

2.2 Configuration arrangements are described.

Rangemay 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.

2.3 Operating arrangements are described.

Rangemay 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.

2.4 Contact requirements are described.

Range contact pressure, alignment, lubrication, contact materials.

2.5 Operating mechanisms are described.

Rangeincludes but is not limited to: linkages, motor drives and controls, mechanical and electrical interlocks, auxiliary contacts, timing and synchronisation.

2.6 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.

Rangeincludes but is not limited to: functional checks, contact resistance measurement, diagnostic inspection and service.

3.2Maintenance requirements are described.

Rangeincludes 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.

Status information and last date for assessment for superseded versions

This CMR can be accessed at

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 if you wish to suggest changes to the content of this unit standard.