DSR 01 002 HV System Operations - UK Power...

UK Power Networks DSR 01 002v4.0

HV System OperationsOwner

Name Peter VujanicTitle Head of Health and Safety

Signature

Date 01 May 2016

Authoriser

Name Dudley SparksTitle Operational Safety Manager

Signature

Date 01 May 2016

This document forms part of the UK Power Networks Integrated Management System and compliance with its requirements is mandatory. Departure from these requirements may only be taken with the written approval of the above authoriser.

Revision Record

Version number 4.0 What has changed?The following sections are new or have been modified: 8.2, 8.5, 8.6, 8.10, 8.13.1, 8.13.2, 8.13.5, 8.13.9, 8.22 & 9.1.

Why has it changed?Incorporating legacy procedures

Date published 01/05/2016

Next review date 01/05/2019

Prepared by N Saunders and R Hembling

Version number 3.0 What has changed?The following sections are new or have been modified: 8.5, 8.6, 8.12, 8.15, 8.19 & 8.20.

Why has it changed?Incorporating legacy procedures

Date published 17/3/2014


Prepared by N Saunders

Version number 2.0 What has changed?No changes

Why has it changed?Date published 21/10/2013


Prepared by N Saunders

This printed document is valid at 06/05/23, check after this date for validity. of 23


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Contents

1.0 Introduction and Purpose...............................................................................................32.0 Scope................................................................................................................................33.0 Objective...........................................................................................................................34.0 References.......................................................................................................................35.0 Definitions........................................................................................................................46.0 Responsibilities...............................................................................................................57.0 Records............................................................................................................................68.0 Process Detail..................................................................................................................69.0 Appendices....................................................................................................................22



1.0 Introduction and PurposeThis procedure sets out fundamental rules and guidance for switching and operations on all High Voltage networks up to and including 132kV that are owned or operated by UK Power Networks.

2.0 ScopeThis procedure is supplementary to the Distribution Safety Rules, and does not authorise any departure from them, except where specifically stated. It should be read in conjunction with those rules.

This procedure details how to obtain permission to operate the HV network, and responsibilities and safety instructions for those who do operate the HV network.

It includes

Pre-planning switching operations

Use of switching schedules

Basic Rules for switching operations

Communications between Control and Field staff

Switching Across Operational Boundaries

Isolation & Earthing

Application of Circuit Main Earths

Changing HV fuses submerged in oil

Special switching procedures in accordance with DSR rule 1.6

Switchgear Interlocks

Use of Insulated Rods in the Vicinity of Overhead Lines

3.0 ObjectiveTo supplement the UK Power Networks Distribution Safety Rules and provide a process for UK Power Networks with regard to switching operations.

4.0 References

DSRs Distribution Safety Rules

DSR 01 009 Operation of SF6 Switchgear

DSR 01 013 Safety Documents

DSR 01 015 Identification of Points of Work

HSS 01 105 Putting People to Work

HSS 40 023 Energisation of Networks Following Faults and Emergencies

HSS 40 048 Investigation and Management of AVC Failures



HSS 40 047 Use of Portable Earths

HSS 40 042 HV Switching – Remote Operating Devices

NOP 50 001 Pre and Post Outage Checks for EHV Networks(Grid & Primary Substations)

GOP 13 Generic Task Risk Assessment HV & EHV Underground Switching

GOP 17 Generic Task Risk Assessment HV & EHV Overhead Switching

5.0 Definitions

Confidence Switching

Opening and closing of a circuit breaker by electrical means either on site or remotely and, where possible, recording of circuit breaker operating times via a remote terminal unit

Distribution System The complete electrical system for which UK Power Networks has responsibility in one or more of the following areas: Control, Operations, Maintenance and/or construction

DSRs Distribution Safety Rules

Field Control Where control of an agreed section of network is passed by the Control Centre to a Senior Authorised Person, who is authorised to take Field Control on site.

LV Switching Low voltage operations carried out on the network operating at or below 1000V.

Primary HV Network

That part of the HV network supplying primary substations

Primary Substation A substation forming part of the HV network where the transformer output is above 1kV, and is not a secondary substation

RTU Remote Terminal Unit. A generic name for the device used to remotely control plant at a substation. It is located at the substation and contains a modem and control unit.

Secondary HV Network

That part of the HV network supplying secondary substations

Secondary Substation

A substation forming part of the HV network where the transformer output is at or below 1kV, or the input voltage is 11kV or less.

Sequence Of Operations

Two or more switching items carried out in succession without reference back to the appropriate Control Engineer between operations.

Substation Any premises or that part of any premises, in which electrical



energy is transformed, converted or controlled.

Switching Party Two or more appropriately authorised persons, at separate locations, acting under the direction of the Person in Charge, who jointly execute an approved Sequence of Operations within a switching schedule.

Switching Schedule

A check list and record of operations required to safely carry out a specified operational objective. It is also the Control Engineer's notice of the proposals for a sequence of switching

6.0 ResponsibilitiesIn addition to the requirements of DSR 9.5, the Control Engineer is responsible for

1. Directing and approving running arrangements of the Distribution System for load flow and short circuit level control and in accordance, where appropriate, with agreements with other interested parties.

2. Deciding, in discussion with other interested parties, whether system conditions will allow pre-arranged or additional outages of apparatus or circuits to take place.

3. Making system arrangements for the release of High Voltage Apparatus.4. Pre-checking, when necessary, the contents of switching schedules.5. Approving switching schedules.6. Consenting to the implementation of a switching schedule and the operations

contained in it.7. Carrying out HV Switching operations by remote control.8. Maintaining continuity and security of supplies on the Distribution System together

with control of equipment.9. Agree system electrical safety before consenting to the issue of a Safety Document. 10. Allowing the start, and recording the times, of switching operations.11. Ensuring that the name of the Person in Charge of a Switching Party is stated on the

switching schedule12. Ensuring maps and other displays are dressed where necessary with the appropriate

indicators at the correct time.13. Ensuring that the engineer who takes over the next shift is fully briefed with the

operating conditions of the system coming under their control.

All staff operating on the distribution system are responsible for;

1. Working in accordance with the Distribution Safety Rules, this procedure, and any additional procedures, bulletins, restrictions, special operating conditions and instructions issued by or on behalf of the director of Safety, Strategy and Support Services.

2. Ensuring that they have the correct level of authorisation for any operations they are carrying out on the Distribution System including issuing safety documents. Note that authorisation gained in UK Power Networks is regional and therefore may not apply to more than one region.

3. Providing appropriate supervision for field operators under training.4. Ensuring that they possess a network diagram for any network that they are

operating on, if available. 5. Carrying out an operation or sequence of operations to the instructions of the Control

Engineer or when used, the direction of the Person in Charge of the Switching Party.



6. Ensuring that persons receiving safety documents are competent to do so. 7. Carrying out safety procedures as required by UK Power Networks.8. Ensuring the security of operational keys.

The Senior Authorised Person or Authorised Person in charge of work is responsible for ensuring a safe zone of work has been provided to avoid danger from the electrical network.

7.0 RecordsThe HV diagram in the Control Centre shall be dressed to reflect the current configuration of the distribution network and with any other relevant details (e.g. faulty apparatus, safety documents). This shall include reference to any part of the network that has been transferred to Field Control (see section 8.8 below)

The recording of switching operations is detailed in section 8.9 below.

Switching Schedules and related safety documents shall be retained for 12 months, and be available for scrutiny.

Records shall be maintained of the authorisation level of all people who have access to or operate on the Distribution Network.

8.0 Process Detail

8.1 General Rules for SwitchingIn addition to the requirements of DSR section 3.5, the following rules shall apply when switching

1. The Control Engineer’s consent shall be obtained immediately before commencing a single operation, or a Sequence of Operations.

An exception to this rule is where emergency switching has to take place: an authorised person may carry out or instruct switching to be undertaken, that has not been pre-approved by a Control Engineer, where he believes that such action is necessary to remove a danger to life. Such actions shall be limited to the removal of the dangerous condition from the distribution system, and must be reported to the Control Engineer as soon as possible.

2. If you make an error whilst switching, on no account attempt to rectify the error by another operation. The Control Engineer shall be contacted before any further switching takes place.

8.2 General Guidance for Switching1. Fully understand and obey the Distribution Safety Rules. They are drawn up for

your protection and the protection of those working with you.

2. Use the switching hierarchy listed in DSR rule 3.5.7.

Note: Operation via a relay is not recommended due to the possibility of intertripping, unless it is part of relay testing

3. Do not trust your memory; consult your written instruction immediately before carrying out any operation.



4. Understand the equipment that you are required to operate. Always ask if in doubt and do not experiment with live switchgear.

5. Always check that you are at the right location. If the substation name label is missing or illegible, it may be possible to identify the substation by checking all switchgear labels.

6. Make a visual inspection of all the switchgear before carrying out any switching operations (including the integrity of the substation earthing). If the switchgear shows any signs of distress, notify the Control Engineer immediately and arrange for a detailed examination to be made.

7. Check the position of any switch that you are about to operate. Is it in the position (closed, open or earthed) you expect from your instructions? If not, find out why.

8. Check the title of any circuit and the function of the operating handle twice before operating. If in doubt, ask.

9. Wherever reasonably practicable, use a Remote Operating Device for oil filled switchgear (refer to HSS 40 042 HV Switching Remote Operating Devices)

10. Before operating a switch that is fitted with a Reverse Operation Delay Handle, ensure that the handle is working properly. Do not attempt to operate the switch without the correct handle.

11. During any switching operations, only those persons necessary for conducting the operations should be within the vicinity of the switchgear.

12. When switching, only remove the padlock(s) necessary to allow the current operation. Immediately lock it again when that operation is complete.

13. Operate switches without hesitation; you may be closing onto a short circuit. If a circuit breaker trips immediately on closing, establish the reason before attempting to reclose.

14. Immediately after completing an operation, look at the switch position indicator to check that you have in fact performed the operation intended in accordance with your instructions. Any mal-operation shall be reported to the Control Engineer immediately.

15. Never run within a substation or enclosure whilst switching. Pause and think before you act. All actions should be deliberate, never impulsive.

16. All relay flag indicators that have operated must be correctly recorded before re-setting.

17. When leaving a substation unattended, make sure it is securely locked.

8.3 Use of Switching Schedules for planned Switching Where a series of pre-planned operations are to be carried out then a switching

schedule shall be prepared and shall be approved by a Control Engineer. In exceptional circumstances the Control Engineer may agree that planned work can proceed by direct instruction if it is operationally advantageous to do so.

Where fault repairs such as switchgear replacement can be pre-planned, a switching schedule should be prepared in the normal way.

Due to the relative simplicity of the operation, a pre-approved switching schedule will not be required for the “confidence” switching of circuit breakers or switches which are carried out by Control Engineers remotely, using telecontrol.



All outages affecting the Primary network shall be subject to appropriate planning and approval by Outage Planning - see section 8.5 below. The switching schedule submitted from the field should normally be limited to the items required to achieve the final isolation, application of circuit main earths and the issue of safety documents, but can be complete for simple outages such as transformer feeders.

Other switching operations, to configure the Primary network for the outage, shall be carried out to the instructions of the Control Engineer, referring to any advice from Outage Planning and the known state of the Primary network.

The schedule will be approved by a Control Engineer and then be available to the originator as an authorised switching log.

If conditions have changed on the day then the switching will become unscheduled and under the discretion of the Control Engineer.

For work on the Secondary network the switching schedule should normally include all items required for the planned switching, including configuration of the network and restoration to normal running conditions.

The person preparing the switching schedule shall take due regard of system security issues. As far as reasonably practicable the nature of the outage, and the timing, shall aim to minimise the risk to customer supplies.

Unusual or high risk outages on the secondary network shall be discussed with the Control Centre before the switching schedule is submitted. Where appropriate, an emergency restoration plan shall be agreed. See section 8.5 below.

If HV isolation is necessary for work to be carried out on LV apparatus (e.g. on transformer LV connections) then a HV switching schedule shall be prepared and submitted.

Items shall be included on an HV switching schedule to confirm LV isolation, if applicable.

A switching schedule shall be submitted by a person authorised to carry out the operations listed in the schedule.

An exception can be made for persons under training to become Authorised Persons. In such cases, the switching schedule shall be counter-signed by a person authorised to carry out the operations listed in the schedule, or in the case of Power On, annotated as checked by the name of the suitably Authorised mentor.

The Control Engineer at the relevant voltage level is responsible for approving all switching schedules.

A switching schedule shall only be used if it has been approved by a Control Engineer.

A switching schedule shall only be used once it has been ascertained by the Control Engineer and all members of the switching party, that all paper copies are the same version as the Control Engineer’s.

Approval of a Switching schedule does not signify that the Control Engineer has released the apparatus concerned. Network conditions may have changed since the schedule was approved.

No departure or variation from an agreed switching schedule shall be made without the sanction of the Control Engineer. Where changes are agreed, these shall be approved and recorded by the Control Engineer. The Field Operators shall also amend their copies of the switching schedule accordingly.



The Authorised Person, or in the case of a Switching Party (see section 8.7 below), the Person in Charge, and the Control Engineer shall record, on their copies of the switching schedule, the date and time that consent for an operation or a sequence of operations was given. The Authorised Person, or in the case of a Switching Party, the Person in charge, will record on his copy the date and time of each completed operation detailed in the switching schedule.

8.4 Unplanned Switching For unplanned (normally fault) switching, the following procedure shall be used.

The Control Engineer shall raise an unplanned (also known as On Demand) switching log, which shall be allocated a switching schedule number. This number shall be communicated to all field operators carrying out switching operations on the incident.

Every instruction must be written down and read back in full to the sender to ensure that the message has been accurately received. An exception can be made if customers are off supply and the switching operator is communicating with the Control Engineer directly from the switch that he is instructed to operate, and only a single instruction is to be given. In such circumstances the instruction shall be repeated to the Control Engineer who shall remain in contact with the switching operator until confirmation is given that the operation has been completed.

Once customer supplies have been restored, further operations to complete repairs and restore the network to normal running conditions shall be recorded on the unplanned switching log.

The Control Engineer shall record the time of instruction and completion of all operations on the log. This shall include the times that Field Control has been granted and returned to the Control Centre for the relevant section of network.

Where switching operations cannot be agreed between the Control Engineer and the switching operator, the Network Manager may take the lead (subject to the requirements of Distribution Safety Rule 1.7).

8.5 Contingency Planning The responsibility for co-ordinating the contingency plans on the Primary Network lies

with the Outage Planning section in consultation with Field and Control Engineers.

On the Secondary network the responsibility for providing the plan will be with the originator of the switching schedule.

In both cases copies of the contingency plan will be held in readiness at the Control Centre throughout the planned outage.

When there is a risk of trip on any circuit, the work is to be agreed with the Control Engineer before starting

Pre and post switching checks on EHV networks (Grid and Primary Substations) shall be carried out in accordance with NOP 50 001.

Where it is not possible to complete work and restore the network by the end of the working day, and the circuit could be required in an emergency, the Recipient of the Safety Document shall confirm to the Control Centre the state of the network and the status of safety documents. The safety document shall be returned to a recorded place and shall be collected before work recommences. If there is a need to cancel the safety document the procedure detailed in DSR 01 013 shall be followed.



8.6 Sequence of Operations Subject to the consent of the Control Engineer a Sequence of Operations may be

carried out by a suitably Authorised Person, or by a Switching Party (Note: this is an Approved variation of DSR rule 3.5).

A Sequence of Operations shall be carried out strictly in accordance with the agreed instructions. Field operators may not amend or add to the switching instructions. This includes the position of circuit main earths.

If it proves impracticable to carry out any item as agreed, then the sequence of operations shall be stopped and the Control Engineer advised. Any further switching operations shall be to the direct instruction of the Control Engineer.

As soon as possible after the Senior Authorised or Authorised Person has carried out all of the operations contained in a sequence of operations, they shall notify the Control Engineer of the time of the last operation in that sequence.

The person implementing, or the Person in Charge of co-ordinating a switching schedule, shall establish direct communications with the Control Engineer in the following circumstances as a normal requirement. Or, if this is not possible, at a point agreed between the Control Engineer and Field Operator:

a) Immediately prior to the start, and at the end of, a Sequence of Operations.

b) Immediately after isolation has been completed. Note some equipment requires selection of earth as part of the isolation process.

c) Following removal of the last Circuit Main Earth.

d) Immediately prior to and following the spiking of an HV cable.

e) Immediately prior to making, and following the removal of, a high voltage parallel between two Primary substations or across Primary substation busbars where the bus-section and / or bus-coupler is open.

f) Where the autoclose/autotrip is inhibited or restored in Primary substations.

g) On a Primary System circuit, before isolating, earthing, removal of earths, or making apparatus ready for service.

h) Before the commencement of Live Line work when forming part of a normal switching schedule.

i) If a sequence of operations is taking longer than would normally be expected.

8.7 Switching PartiesWhen a switching schedule involves a Sequence of Operations which is to be carried out by a number of suitably Authorised Persons forming a Switching Party, the following procedure shall be adopted:

(i) The Person-in-Charge shall confirm to the Control Engineer that all members of a switching Party have an approved and current copy of the switching schedule.

(ii) The Control Engineer shall then give the Person in Charge of the Switching Party an instruction to carry out the Sequence of Operations.

(iii) The Person in Charge shall then direct the other Authorised Persons to execute items within the Sequence of Operations. They will report the completion times back to the Person in Charge.



(iv) The person in charge of the switching party shall report back to the Control Engineer on completion of the sequence of operations, stating the time of the final operation carried out in that sequence.

(v) If an Authorised Person cannot complete an agreed operation, then they shall report to the Person in Charge of the Switching Party who shall then report to the Control Engineer

This procedure, with regard to switching parties, is an approved variation of DSR rules 3.5.2 and 9.5.4.

8.8 Field ControlRoutine, planned, operations using a switching schedule shall normally be controlled using the Sequence of Operations procedure set out above.

In certain circumstances, particularly for fault operations, it may be appropriate for Control of a section of network to be passed to a Senior Authorised Person who holds the authorisation for Field Control. This transfer shall be agreed between the Network Control Engineer and the Field Control Engineer. Both parties shall reach a clear understanding of the part of the network to be transferred.

The Network Control Engineer shall give the Field Control Engineer a field control reference number when handing over the affected circuit(s). The date and time of transfer to Field Control, and details of the network transferred (including operational restrictions), shall be logged by the Network Control Engineer. The Control diagram shall be dressed to show the network transferred to Field Control.

Where Field Control has been granted, The Field Control Engineer shall keep an accurate log of all operations carried out, and the issue/cancellation of safety documents, to facilitate reporting requirements on the circuit(s) under his control.

Field Control shall not be used to control the following:

Paralleling of feeders supplied from different busbars or Grid Supply Points.

Networks containing known generation.

The closing or opening of open points between feeders. Unless the whole of a Primary sub-station 11kV network has been transferred to Field Control.

Operations across boundaries with non-UK Power Networks controlled systems, except in cases where the same Field Control Engineer has already taken control of a HV Customer Network.

Unscheduled load transfer or load reduction.

The following additional provisions shall be applied to the use of Field Control:

Field Control shall not be transferred from one Field Control Engineer to another. If a transfer of Field Control is appropriate and agreed, with Network Control, the original Field Control shall be cancelled and re-issued to the new Field Control Engineer.

Where a Field Control Engineer cannot complete a programme of work he must transfer control back to the Network Control Engineer. In the unusual circumstances of a Field Control Engineer unable to transfer control back to Network Control then another suitably authorised person shall visit site and confirm the network conditions and agree with the Network Control Engineer how further operations will be done.



Field Control shall not normally be extended while work is stopped overnight or if there are likely to be lengthy delays due to shortages of staff or materials.

The Field Control Engineer may direct other Authorised Persons to carry out switching operations in the same manner as the use of Switching Parties detailed in 8.7.

Where work or operations under Field Control may result in alarms being received at the Control Centre, the Field Control Engineer and the Network Control Engineer shall agree on the actions to be taken on receipt of such alarms. This will include monitoring of the ASC alarm during fault switching on networks equipped with ASC earthing.

Field Control shall normally be terminated once all intended work has been completed. On transferring Control back to the Network Control Engineer, the Field Control Engineer shall report the state of the network, including the position of switchgear and any changes to the network.

In the event of any unplanned incident, switching error or electrical accident occurring while Field Control is in use, the Field Control Engineer shall immediately suspend further operations and report to the Network Control Engineer. The Network Control Engineer shall decide what action is to be taken and whether Field Control should be terminated.

8.9 Recording of Switching OperationsA record shall be kept by the control engineer of all operations carried out on the HV network, including:

(i) All instructions regarding switching.

(ii) Each operation of a circuit breaker and, where appropriate, protection apparatus indications and alarms.

(iii) Each operation of a disconnector and isolation of a circuit breaker.

(iv) Each operation of an earthing switch and application, or removal, of a Circuit Main Earth.

(v) The failure of plant or apparatus together with relevant details of any interruption, and restoration, of supplies.

(vi) The commissioning, taking out of service or re-commissioning of plant and apparatus together with relevant details.

(vii) Relevant details relating to control of tapchangers.

(viii) Any items of general operational importance and such others as may be directed.

(ix) Alteration to protection settings.

(x) Alterations to AVC controls.



8.10 Special Switching procedures in accordance with DSR 1.68.10.1 11kV/6.6kV High Voltage Separable Connectors

A High Voltage Separable Connector is a separable, single phase device for terminating a high voltage cable, capable of being simply connected or disconnected to alter circuit configurations.

Types of High Voltage Separable Connector include:-

(a) Bolted Elbow

(b) Plug-in Elbow

(c) Replacement Plug

Connections shall only be made or broken after the issue of a Permit-to-Work or Sanction-for-Test.

8.11 CommunicationsAt the commencement of every telephone conversation relating to switching, isolation, earthing or safety precautions on the Distribution System, the personnel concerned must identify themselves, by name, switching schedule number, and the location at which they are working. This conversation must take place person to person. Messages must not be left on automated systems such as voicemail.

Every telephone message relating to switching, isolation, earthing or safety precautions must be clear and concise. Circuit designations must be given in full, abbreviations are not permissible. When giving consent for, or confirming completion of, a Sequence of Operations on a pre-approved switching schedule, only the switching schedule number, item numbers and consent or completion time need be given.

During a telephone conversation, there may be ‘preamble’ discussions between the Control Engineer and the Field Engineer about the proposed switching operations. To indicate that a formal switching instruction is about to be given the Control Engineer will start the instruction with the word “TIME”.

All unplanned switching instructions shall include the following information:

Time Using the 24 hour format

Location Substation Name

Switchboard Designation If there is more than one switchboard

Operation The operation to be carried out (Open, Close, Close to Earth etc.)

Circuit The switch and circuit designation

Example: “TIME 09:05. At Essex Road substation, Open the Strand 11kV circuit breaker 1234”.

All switching instructions shall be carried out as soon as is practical and without undue delay.



8.12 Geographical and Operational BoundariesUK Power Networks Authorised Staff shall only operate on the network for which their authorisation certificate allows, which may mean only one region of the company. If switching is across regional boundaries, and the operator is not suitably authorised for both sides of the boundary, there will normally be an Authorised Person for both areas to carry out the switching. The Control Engineers for each area will discuss and agree how the switching will be carried out.

Any operations on the UK Power Networks Distribution system that are carried out that may involve the interface with the National Grid system shall be in accordance with the requirements of the UK Power Networks Distribution Safety Rules, this procedure, and the requirements of the Site Responsibility Schedule at the location.

8.13 Isolation & Earthing 8.13.1 IsolationDevices used for isolation must provide adequate physical separation or sufficient gap (refer to section 8.13.4 below for equipment which cannot be used as a point of isolation).

On all circuits, including teed circuits, isolation as required by the DSRs must be completed before earthing commences. A point of isolation shall be made at any HV/LV transformer within the isolated system that interconnects with a HV/LV transformer which is outside of the isolated system.

Where an “open” operation is carried out remotely, a “confirm open” instruction will be required before the next operation.

8.13.2 VT IsolationAll withdrawable VTs shall be racked out dead.

8.13.3 Overhead Isolation PointsOn overhead networks, rule DSR 4.1.1(b) shall be complied with.

Where an in-line section above an ABSD has permanently fitted jumpers a “confirm open” instruction will be required.

On the following overhead apparatus the points of isolation are deemed as follows;

Soule and Sectos Switch

Apparatus with HV knife blades – the HV knife blade links after they have been opened.

8.13.4 Apparatus which Shall not be used as a Point of IsolationThe following equipment apparatus does NOT provide adequate isolation:

Non-withdrawable circuit breakers merely in the open position, unless the circuit breaker complies with UK Power Networks engineering design standard requirements for a disconnector. i.e. Brush Falcon and Yorkshire Ringmaster

SF6 switchgear where there is no method of confirming the gas pressure (refer to DSR 01 009)



A single overhead line porcelain or glass disc insulator which does not form a point of attachment to any supporting pole or structure, but is inserted directly in the line conductor. (This restriction does not apply to single 11kV shatterproof tension insulators.)

8.13.5 Securing Isolation

A point of Isolation Shall normally be secured by one or more of the following means:

a) application of a Safety lock and caution notice or caution band,b) removal of circuit components and application of a caution notice or caution

band or caution tape,c) application of the normal switchgear lock where it is an individual key lock

(usually in Primary or Grid substations) and a caution notice

Where jumpers are disconnected but not removed they shall be securely fixed in the isolated position.

Safety locks shall be fitted to switchgear at all points of isolation following the sectionalising of defective or suspect apparatus.

Safety locks shall only be used with the attachment of Caution Notices (and if required Danger Notices) or the locking of controls or barriers, at points of Isolation.

In some instances as part of the work the point of isolation may disappear due to apparatus removal, for example a transformer pole change on an islanded network the PC 400 fuse holders will be removed and replaced. In these cases the SAP will consider if the standard point of isolation could be further along the LV network or if not how the point of isolation will be controlled. This will be recorded on the PTW and with Control.

To secure a point of isolation on overhead lines a Safety lock and Caution Band shall be locked around the pole at or about eye level. For more than one point of isolation on the same pole then a Safety lock and Caution band will be fitted for each point of isolation.

Locking arrangements for some specific overhead apparatus are as follows;

Soule and Sectos switches without an external operating lever - The DC isolator shall be opened and a SL&CN applied to the door of the cabinet. (There is no high level isolation level.)

For conventional handled ABSDs the SL&CN shall be applied through the normal handle locking eye

For Drop Out Expulsion Fuses (DOEF), solid link type DOEFs and LV Fuses that are used to provide the Point of Isolation they shall opened and removed and either secured to the pole with the Caution band and Safety lock or secured in a safe location

8.13.6 Circuit Main EarthsSection 4.3 of the Distribution Safety Rules refers.



Where reasonably practicable the discharging and earthing of all apparatus shall be by means of a fully rated high voltage earthing switch or by use of a circuit breaker. This operation may be carried out remotely using telecontrol but the Senior Authorised Person who is to issue the safety document must then ensure that the switch or circuit breaker has correctly closed to the Earth position.

Extension type or portable Circuit Main Earths shall only be applied by a person authorised to do so or a competent person acting under the personal supervision of someone authorised to do so.

8.13.7 Earths on Overhead Lines up to And Including 33kV

(Does not include Multiple Circuit Overhead Lines where one circuit operates at 132kV.)

Unless instructions detailing the Additional Earths to be applied are included on the Permit-to-Work the recipient of the Permit-to-Work Shall ensure Additional Earths are applied in accordance with DSR 5.10.

In addition, an Earth shall be applied between any Live overhead line crossing and the point of work (as per DSR 5.10.3 (b)).

8.13.8 Securing EarthingA Circuit Main Earth applied at a lockable point of earthing Shall normally be secured with an Operational Class lock, or its normal switchgear lock, and a Circuit Main Earth notice attached.

Where because the design of the equipment, earthing results in the removal of the safety lock (applied to a point of isolation) the following actions will take place.

To progress switching operations, a discussion and agreement shall take place with the control engineer on confirming that the point of isolation is maintained.

The switchgear type and location shall be reported to AIRLine for the attention of HSS and Asset management.

A Circuit Main Earth established by the application of portable Earthing Leads Shall have a Circuit Main Earth Notice attached. When a portable earth is applied on a pole or structure carrying exposed live conductors a “Danger do not climb” flexible notice Shall be attached to the pole or structure outside working and access clearances. Portable earths Shall only be applied to the pole or structure where working and access clearances can be maintained.

8.13.9 Special Earthing proceduresSee Appendix A for special procedures in accordance with DSR 1.6.

Interleaved Networks - where DSR rule 4.1.1 (c) cannot be complied with

Earthing of Busbar Spouts, Busbars and busbar connections or multi-panel switchboards where rule 5.4.2 (b) cannot be complied with.

Portable Earths at 132kV Tandem Isolators



8.13.10 Secure Retention of KeysKeys to locks at points of Isolation shall be kept in one or more of the following places:

(a) In the custody of a Senior Authorised Person or Authorised Person with authorisation to switch at that voltage level.

Note, Senior Authorised or Authorised Persons Shall not retain keys to individual key locks, as these should remain on site.

When a Senior Authorised or Authorised Person holds keys to more than one isolated circuit, Safety Key Envelopes should be used to distinguish between the different sets of Safety lock keys.

(b) In a Safety Key Envelope. A sealed Safety Key Envelope provides a safe place for the deposit of keys to locks at points of Isolation. Details of the circuit isolated and key numbers shall be written on the front of the envelope. A sealed Safety Key Envelope shall be kept in a place secured by an “Operational Class” lock when not in the custody of a Senior Authorised or Authorised Person.

(c) In a Key Safe

A Key Safe is a secure box having more than one lock which enables one or more key holder(s) to individually secure the contents of the box. Key Safes Shall be used at joint user sites, e.g. NGC, Network Rail or another Distribution Network Operator. For work on the 132kV system, all Safety lock keys will be locked in Key Safes before the issue of Safety Documents.

(d) In a Safety Key Box

A Safety Key Box is a secure box, lockable with an operational class padlock, installed as part of the permanent substation furniture and clearly marked “Safety Keys”. At least one Safety Key Box Shall be provided at each site where individual key locks are used, other than at joint user sites where Key Safes are used. Keys to individual key locks at points of Isolation should be placed loose in a Safety Key Envelope in the box which Shall then be locked with an Operational Class lock.

8.13.11 RecordingWhen the Safety Keys, or removed circuit components, are not in the custody of a Senior Authorised or Authorised Person the Control Engineer Shall record their location.

8.13.12 Removal of Circuit Main Earths after testingWhen apparatus has been tested under the terms of a Sanction-for-Test, Circuit Main Earths do not need to be replaced upon cancellation of the Sanction-for-Test, provided that the circuit is then to be made LIVE from the point of test. Confirmation that the Circuit Main Earths have been removed shall be recorded in the appropriate logs and/or Switching Schedule by the person cancelling the Sanction-for-Test, and by the Control Engineer.

Where practicable, the switch or circuit breaker where the testing has taken place shall be closed to energise the circuit and, if necessary re-opened before further switching takes place.

If it is not practicable to energise the circuit from the point of test, all Circuit Main Earths shall be re-applied before the Sanction-for-Test is cancelled. Subsequent



removal of the Circuit Main Earths shall then be carried out as switching operations and shall be recorded in the logs and/or switching schedule.

8.14 Work on apparatus and supplying circuit breakerOn Primary Circuits, where it may be possible to work on both the apparatus and the circuit breaker(s) supplying that apparatus the following procedure can, with the consent of the Control Engineer, be adopted:

(i) The circuit shall be made dead using the circuit breaker, then shall be isolated and earthed where there is provision to do so.

(ii) The circuit shall be proved not live at the point where a portable circuit main earth is to be applied using an approved testing device or other suitable means.

(iii) Approved portable earths shall be firmly applied to the circuit conductors, between the circuit breaker(s) in the earth position and the point of work.

(iv) Safety clearances shall be adhered to when applying portable earths in the vicinity of live HV apparatus. A special procedure shall be applied for 132kV tandem isolators where safety clearances cannot be otherwise guaranteed.

(v) The circuit breaker(s) shall then be isolated from the system and all busbar shutters (where fitted) locked with Danger Notices attached. No work will be allowed on the circuit shutter spouts, which must be locked with Caution Notices attached.

(vi) A Permit-to-Work must be issued for work on the apparatus, listing the portable earths as the Circuit Main Earths and specifying all the above precautions.

(vii) Work on the circuit breaker(s) can be carried out only after the relevant Safety Document has been issued.

(viii) The portable Earths shall remain connected to the Circuit conductors at all times while the Permit-to-Work is in force.

8.15 Transformer TappingManual operation of a tap changer with the transformer live is strictly prohibited. For more on managing AVC failures, refer to HSS 40 048.

8.16 Changing HV Fuses8.16.1 Submerged in OilTo mitigate the risks identified by the generic task risk assessment, it is prohibited to replace oil-submerged HV fuses in switch fuses and ring main units whilst any part of the switch remains live.

Any replacement of such a fuse shall be done as a switching operation but the whole switch must be made dead. This includes the incoming feeder(s) and applies to both free-standing switch fuses and ring main units.

Once the fuse or fuses have been changed, the switch fuse shall be closed whilst the circuit is dead. The switch fuse can then be energised from a Fault Making switch or Circuit Breaker.



8.16.2 11kV/6.6kV Fused End-Boxes and Fused TransformersA Permit-to-work or Sanction-for-test is always required for replacement or removal of High Voltage Fuses situated within a distribution transformer fused end-box and accessible fuses in pad-mount, compact and micro transformers.

8.17 Switchgear InterlocksInterlocks are provided to assist in the prevention of incorrect switching sequences and only under exceptional circumstances should their function be defeated. If it is not possible to carry out a particular switching operation an investigation must be carried out to determine the reason. It must not be assumed that the interlocks have failed.

Interlocks on switchgear may be defeated only by agreement between a Senior Authorised Person, and the Control Engineer. The Senior Authorised Person must be accompanied and checked by a second appropriately Authorised Person

Before consenting to the operation to defeat interlocks, the Control Engineer shall establish the status of the apparatus involved, and any other apparatus that may be affected. Once the status of the apparatus is deemed satisfactory, the Control Engineer shall issue the instruction to defeat the interlocks. These instructions shall be issued directly to the Senior Authorised Person who is to defeat the interlocks, and separately to the second appropriately Authorised person.

Both Persons shall then separately report back to the Control Engineer on completion of the operation.

8.18 Abnormal IncidentsAny abnormality found by the switching operator affecting any Network apparatus shall be reported immediately to the Control Engineer. Similarly, if the Control Engineer becomes aware of an abnormality which may affect an operation, which is to be carried out by the Field Operator, then they shall make immediate contact with the Field Operator.

Where a fault is suspected on the HV Network the Control Engineer may consent to a suitably Authorised Person taking the following steps:-

Opening a circuit breaker to make the relevant section of HV Network dead, assuming that the circuit breaker has not already tripped on a suspected fault;

Isolating the switch or circuit breaker controlling the circuit.

Inserting an approved testing device (e.g. Victor Test Device) into the circuit spouts or test orifices, strictly for the purpose of testing the circuit.

At the completion of these operations the Authorised Person must report his findings to the Control Engineer together with the position of any circuit breaker or switch that has been operated.

8.19 Proving Apparatus Dead During a Supply FailureDuring a period where the surrounding area is without supply, the normal process of proving isolation should be suspended until supply is restored.



If it is necessary for the work to proceed before supply is restored to the surrounding area, the authorised person responsible for making the apparatus dead shall confirm correct isolation by using one of the methods below.

1) Visual or electrical tracing of the circuit to the isolation points, or

2) Isolation of a greater portion of the network to remove any doubt that the apparatus to be worked on will remain dead. This may include isolation of network at a higher voltage than that to be worked on.

When the surrounding area is to be re-energised, all work will be suspended.

Isolation points should then be re-affirmed before recommencing work.

If it is not possible to prove isolation points by these means, work will be carried out using live techniques or suspended until the surrounding network has been re-energised.

8.20 Use of Insulated Rods in the Vicinity of HV Overhead LinesAll work on HV overhead lines, involving the displacement or manipulation of conductors, must follow the full requirements of section 4 of the DSRs. The only exceptions are as follows:

When suitably trained and authorised staff are working in accordance with HSS 40 044 Dead Stick Working.

When a suitably authorised LIVE LINE TEAM are carrying out the work in accordance with the Live Line Manual and its procedures.

The use of switching rods to remove debris such as branches, twigs and vermin, from de-energised circuits, is permissible by an authorised HV OH switcher or a competent person under his personal supervision. In all circumstances the situation must be risk assessed and agreed with the Control Engineer.

8.21 Switching Following FaultsHSS 40 023 Energisation Following Faults and Emergencies provides guidance on fault restoration.

The following shall be considered when operating on Networks that have been subject to recent fault activity:

Visual checks - be aware of your escape route

Route patrol

Reduction of fault current levels

Use the switching hierarchy

Time delay

8.22 Superseded DocumentsEPN Approval 21

EPN Approval 22

EPN Approval 24



EPN NOP 62 004 Sequential Switching

EPN V12/S3/8 Manual Operation of High Voltage Oil Insulated Switchgear with Manual Assisted or Power Closing Mechanisms

EPN V12/S3/21 Operation of High Voltage Separable Connectors

HSS 40 019 Proving Apparatus Dead During a Supply Failure

HSS-406-OB-61 Changing HV Fuses Submerged in Oil

HSS-406-OB-71 referring to energising from the point of test

HSS-406-OB-79 Use of Insulated Rods in the Vicinity of HV overhead Lines

HSS-406-OB-101 Overhead Points of Isolation

LPN COP5 (part)

LPN Eoi-22 HV networks – interleaved type

LPN NOP 72 004 Operational Control of the London HV Secondary Distribution System

SHE 400-PR-01 Interim procedure on EHV fault management.

SHE 406–OB-18 Operation of 22kV system

SPN Ints 4.3.4 (b), 5.4.2 (b) and 5.5.4 (ii)

SPN OI G1/- Basic Rules for Plant Operation

SPN OI G3/- Routine and Emergency Switching Operations

SPN OI G38/- Portable Earths at 132kV Tandem Isolators

SPN Safety Rules Supplement DSR 6/1



9.0 Appendices

9.1 Appendix A – Special Procedures in Accordance with DSR 1.6DSR rule 4.1.1 (c) and interleaved networks

Rule 4.1.1(c) is deemed to be satisfied in relation to HV interleaved networks where the following conditions have been established:-

1. Circuit Main Earths shall be applied at each HV point of isolation. This will be either a circuit breaker in a Secondary Substation or a ring main unit switch on the circuit or both.

2. Further Circuit Main Earths shall be applied to the cable via the nearest adjacent transformer switches on either side of the point of work.

Where this is not possible, the following shall be carried out:

(i) Further circuit Main Earths shall be applied to the cable either side of the point of work at the nearest appropriate transformer switches.

(ii) Those points of isolation between the further Circuit Main Earths and the point of work where earthing towards the cable cannot be carried out shall have their transformer earth switches closed to the earth position.

3. Safety Locks and Caution Notices shall secure all points of isolation and CME labels placed at points where earthing has been carried out.

All other conditions of Distribution Safety Rule 4.1.1 shall apply to HV interleaved networks.

DSR rule 5.4.2 (b)

Earthing busbars of YSE Type IVI switchgear and Reyrolle C. The Circuit Main Earth shall, where reasonably practicable, be applied either at all points of disconnection of High Voltage supply or directly to the busbar spouts of one of the units on the isolated section of busbars (i.e. via a circuit breaker or other Approved device).

Where it is not reasonably practicable to apply the Circuit Main Earth in this way, then all except one of the isolatable units on the switchboard shall be racked out and a Circuit Main Earth applied at the remote end of the circuit of that one remaining unit (this circuit shall not contain any section of overhead line). The remaining unit on the switchboard where work is to be carried out shall be ‘closed’ and secured in this position with a Safety lock.

If this latter method of earthing is adopted, the busbars shall always be proved dead with an Approved voltage testing device before a Permit to Work is issued.

DSR rule 5.5.4 (ii)

If, in order to work on the busbar of a single panel unit or feeder connections, it is necessary to remove the Circuit Main Earth at the point of work, then notwithstanding the requirement of Rule 4.3.4(a), the Senior Authorised Person, shall remove the Circuit Main Earth at the point of work and prove that the



connections at the busbar or feeder spouts are not Live by means of an Approved voltage testing device before they are worked on.

On completion of the work, the Circuit Main Earths shall be re-applied, if necessary, before the Permit-to-Work is cancelled.

If the only earthing devices that can be applied to the circuit are those applied in the spouts and are Circuit Main Earths then, while work is in progress, no other work shall be carried out to the circuit connected to those spouts.

Portable Earths at 132kV Tandem Isolators (Disconnectors)

For the purpose of this instruction a tandem isolator is defined as a switch disconnector where each phase is mounted in line as opposed to side by side.

Each tandem isolator shall be identified by a prominent label affixed to the mechanism box bearing the legend: WARNING – TANDEM ISOLATOR.

Portable earthing leads applied at tandem isolators shall be attached to the special earthing spigot provided or where the Senior Authorised Person in charge of the work considers it to be necessary, the application of portable earths shall be carried out with both sides of the isolator Dead.


DSR 01 002 HV System Operations - UK Power...

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