High Voltage Switching and Earthing – Code of Practice (HV COP)

Flashcards cover HV Switching categories, roles (Nominated Person, Safety Controller, Designated Person), preparation and recording of instructions, earthing strategies (Primary, Portable, Drain), safety requirements, and emergency procedures based on the provided lecture notes.

What are the four categories of High Voltage Switching?

Routine, Operational, Safety and Emergency.

Who is the Nominated Person (Switching) and what are their duties?

A Safety Coordinator, Safety Controller, or Designated Person responsible for issuing HV Switching instructions.

Before issuing HV Switching instructions, what must be consulted?

The equivalent Person(s) of adjacent System(s) that may be affected by the proposed Switching.

What must HV Switching instructions include and be recorded before issue?

The Location(s), identification/nomenclature of the HV Apparatus, and the effect or outcome of the operation.

Name the two types of situations that lead to earths being applied to HV Apparatus.

Manual earthing and electrically operated earthing.

In manual earthing, what sequence must be confirmed before issuing earthing instructions?

All HV Switching causing isolation from all points of supply must be completed.

In electrically operated earthing, what must be identified and discussed?

All points of supply required for the earthing operation and those not required for carrying out the earthing.

What are Primary Earths?

Earth connections applied to HV Apparatus to ensure isolation from live parts, typically immobilised and Locked, placed between the point of work and the isolation.

If it is not practicable to place Primary Earths between point of work and isolation, where may they be placed?

In an alternative position up to 9 m (30 ft) from the tee point or as dictated by an Approved procedure.

Who applies portable Primary Earths and what is the minimum cross‑section required?

A Safety Controller applies portable Primary Earths; minimum cross‑section is 65 mm2 copper equivalent (0.1 in2), except 25 mm2 for electrostatic precipitators.

How often must portable Earthing devices be examined, and when should they be tested?

Examine quarterly and immediately before use; defective Earths must be withdrawn from service; test voltage indicators before and after use.

What device should be used to verify that the conductor is not Live before applying portable Earths?

An Approved Voltage Measuring Device, tested immediately before and after use.

What are Drain Earths and when are they used?

Additional earths used to control induced voltages as specified by an Earthing Schedule, typically when primary earths alone may not provide adequate protection.

How many people must be present for portable Primary Earth application/removal in open substations, and who are they?

Two persons: a Safety Controller and a Person acting under the Personal Supervision of that Safety Controller.

When is a Drain Earth required for overhead line work?

Drain Earths must be issued and applied for contractor work on overhead lines according to H&S CoP/018/004-G.

What is the Emergency Switching rule?

Emergency Switching may be carried out without a written instruction; actions must be recorded retrospectively when circumstances permit; inform the Nominated Person as soon as possible.

What should be done if a switch opens under fault conditions?

Cancel audible alarms; report time, annunciations, and relay indications to the Nominated Person (Switching) and record details; obtain relay indications if initially unavailable.

What must the Nominated Person (Switching) do after an HV Switching operation is completed?

Record the completion time and circuit identifications; confirm completion with the Designated Person; ensure relevant information is passed and acknowledged.

What are the two parts of HV Switching instructions as per 4.5?

4.5.1: An explanatory part describing the objective; 4.5.2: The formal precise instructions including name, Location, actual operation, date and time.

What is required when working on HV apparatus with SF6 gas concerning isolation devices?

Monitor gas pressure; report any loss of pressure to the Nominated Person (Switching).

What is the difference between Routine switching and other HV switching categories in terms of instruction?

Routine switching is approved and defined in a local procedure and does not require a formal switching instruction; Operational/Safety/Emergency require records and instructions as defined.

Which Code of Practice governs cross-border safety precautions for HV earthing?

Code of Practice H&S CoP/018/042-G (Cross Boundary Safety Precautions).