Electrical power transmission and distribution — High ... · distribution — High-voltage...

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KENYA STANDARD KS 1859-1:2010 ICS 29.020; 29.240.01

© KEBS 2010 First Edition 2010

Electrical power transmission and distribution — High-voltage operating regulations — Part 1: Definitions

BALLOT DRAFT, MAY 2010

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KS 1859-1:2010

ii © KEBS 2010 — All rights reserved

TECHNICAL COMMITTEE REPRESENTATION The following organizations were represented on the Technical Committee: Nairobi City Council, City Engineer’s Department. Jomo Kenyatta University of Agriculture and Technology Kenya Polytechnic Kenya Power & Lighting Company Fluid & Power Systems Ltd Ministry of Public Works and Housing Ministry of Energy Kenafric Industries Ltd Power Technics Ltd Rural Electrification Authority The Energy Regulatory Commission Consumer Information Network Kenya Association of Manufacturers Institute of Engineers of Kenya Kenya Electricity Generating Company Ltd ABB LTD Switchgear & Controls Ltd Power Controls Ltd Communications Communication of Kenya Instrument Ltd Kenya Pipeline Company Ltd Telkom Kenya Ltd Meteorological Department Kenya Bureau of Standards — Secretariat

REVISION OF KENYA STANDARDS In order to keep abreast of progress in industry, Kenya standards shall be regularly reviewed. Suggestions for improvement to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are welcome.

© Kenya Bureau of Standards, 2010 Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 12 of 2001 of the Laws of Kenya, copyright subsists in all Kenya Standards and except as provided under Section 26 of this Act, no Kenya Standard produced by Kenya Bureau of Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing from the Managing Director.

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KENYA STANDARD KS 1859-1:2010 ICS 29.020; 29.240.01

© KEBS 2010 — All rights reserved iii

Electrical power transmission and distribution — High-voltage operating regulations — Part 1: Definitions

KENYA BUREAU OF STANDARDS (KEBS)

Head Office: P.O. Box 54974, Nairobi-00200, Tel.: (+254 020) 605490, 69028000, 602350, Mobile: 0722202137/8, 0734600471/2;

Fax: (+254 020) 604031 E-Mail: [email protected], Web:http://www.kebs.org

KEBS Coast Region P.O. Box 99376, Mombasa 80100 Tel: (+254 041) 229563, 230939/40 Fax: (+254 041) 229448 E-mail: [email protected]

KEBS Lake Region P.O. Box 2949, Kisumu 40100 Tel: (+254 057) 23549,22396 Fax: (+254 057) 21814 E-mail: [email protected]

KEBS North Rift Region P.O. Box 2138, Nakuru 20100 Tel: (+254 051) 210553, 210555

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KS 1859-1:2010

iv © KEBS 2010 — All rights reserved

F O R E W O R D

This Kenya standard was prepared by the Switchgear and Distribution Equipment in accordance with the procedures of the Bureau and is in compliance with Annex 3 of the WTO/TB Agreement. This part of KS 1859 was prepared to establish and promote uniform definitions relating to systems, equipment and conditions which may be referred to in high-voltage operating regulations. The intention is to improve safety and reduce training requirements by the use of uniform definitions. Extensive use has been made of IEC standard definitions wherever possible. The reader is referred to IEC 60050 for other definitions that fall outside the scope of this part of KS 1859. In the development of this standard, the South African Standard, NRS 040-1:1999, Rationalized User Specification — High voltage regulations — Part 1: Definitions, was extensively consulted. Assistance derived from this source is hereby acknowledged. Normative and informative annexes A 'normative' annex is an integral part of a standard, whereas an 'informative' annex is only for information and guidance. Summary of development

This Kenya Standard, having been prepared by the Switchgear and Distribution Equipment Technical Committee was first approved by the National Standards Council in June 2010

Amendments issued since publication

Amd. No. Date Text affected

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KS 1859-1:2010

© KEBS 2010 — All rights reserved v

Contents 1 Scope ........................................................................................................................................................ 1 2 Normative references ................................................................................................................................ 1 3 Definitions ................................................................................................................................................. 1

3.1 General [601] .................................................................................................................................... 1 3.2 Generation [602] ............................................................................................................................... 7 3.3 Power system planning and management [603] .............................................................................. 9 3.4 Operation [604] ............................................................................................................................... 11 3.5 Substations [605] ............................................................................................................................ 13 3.6 Definitions not in chapters 601, 602, 603,604 and 605 of IEC 50 ................................................. 17

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KENYA STANDARD KS 1859-1:2010

© KEBS 2010 — All rights reserved 1

Electrical power transmission and distribution — Hi gh-voltage operating regulations — Part 1: Definitions 1 Scope This part of KS 1859 covers definitions for use in operating regulations for high-voltage generation transmission and distribution systems. 2 Normative references The following referenced documents are indispensable for the application of this Kenya Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 50(421), International electrotechnical vocabulary — Chapter 421: Power transformers and reactors IEC 50(441), International electrotechnical vocabulary — Chapter 441: Switchgear, controlgear and fuses IEC 60551, Determination of transformer and reactor sound levels 3 Definitions NOTE 1 3.1 to 3.5 give definitions that have been extracted from IEC 50(601):1985, IEC 50(602):1983, IEC50(603):1986, IEC 50(604):1987 and IEC 50(605):1983. The relevant IEC subclause number is given in parentheses after each definition. NOTE 2 Further definitions that have not been derived from IEC standards are given in 3.6. 3.1 General [601] 3.1.1 Fundamental terms [601-01] 3.1.1.1 active energy The electrical energy transformable into some other form of energy. [601-01-19] 3.1.1.2 alternating current system; a.c. system An electrical system fed by alternating voltage. [601-01-03] 3.1.1.3 asynchronous link An interconnection between two a.c. systems operating at independent frequencies. [601 -01 -13] 3.1.1.4 conversion of electricity The changing of the characteristics of the form and frequency of voltage and current by means of a converter. [601-01-07] 3.1.1.5 direct current system; d.c. system An electrical system fed by unidirectional voltage. [601-01-04] 3.1.1.6 distribution of electricity The transfer of electricity to consumers within an area of consumption. [601-01-10]

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KS 1859-1:2010

2 © KEBS 2010 — All rights reserved

3.1.1.7 electrical power system; electrical power network; power network Particular installations, substations, lines or cables for the transmission and distribution of electricity. [601 -01-02] 3.1.1.8 electrical power system; power system; electricity supply system (in a broad sense) All installations and plant provided for the purpose of generating, transmitting and distributing electricity. [601-01-01] 3.1.1.9 generation of electricity A process whereby electrical energy is obtained from some other form of energy. [601 -01 -06] 3.1.1.10 highest (lowest) voltage of a system The highest (lowest) value of operating voltage which occurs under normal operating conditions at any time and any point in the system. [601-01-23/24] NOTE Transient overvoltages caused, for example, by switching operations and abnormal temporary variations of voltage, are not taken into account. 3.1.1.11 interconnected systems Systems connected together by means of one or more interconnection links. [601-01-1] NOTE This term is also used in the singular for a system whose elements are interconnected. 3.1.1.12 interconnection (of power systems) A single or multiple transmission link between transmission systems enabling electricity to be exchanged between these systems by means of circuits and/or transformers. [601-01 -11] 3.1.1.13 load curve Graphical representation of the observed or expected variation of load as a function of time. [601 -01 -17] 3.1.1.14 load duration curve A curve showing the duration, within a specified period of time, when the load equalled or exceeded a given value. [601 -01 -18] 3.1.1.15 load in a system: a) The active, reactive or apparent power generated, transmitted or distributed within a system. b) The power demanded by a group of consumers classified according to their particulars, and

characteristics, e.g. heating load, daytime reactive load, etc. [601-01-15] 3.1.1.16 neutral point displacement voltage The voltage between the real or virtual neutral point and the earth. [601 -01 -32] 3.1.1.17 nominal voltage of a system; nominal voltage A suitable approximate value of voltage used to designate or identify a system. [601-01-21] 3.1.1.18 operating voltage (in a system) The value of the voltage under normal conditions, at a given instant and at a given point of the system. [601-01-22] NOTE This value may be expected, estimated or measured.

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3.1.1.19 peak load Maximum value of load during a given period of time, e.g. a day, a month, a year. [601-01-16] 3.1.1.20 phase to earth voltage The voltage between phase and earth. [601 -01 -31] 3.1.1.21 phase to neutral voltage The voltage between a phase in a polyphase system and the neutral point. [601-01-30] 3.1.1.22 phase to phase voltage The voltage between phases. [601-01-29] 3.1.1.23 power frequency; frequency Conventionally, the values of frequency used in the electricity supply systems. [601 -01 -05] 3.1.1.24 reactive energy In an a.c. system, the captive electrical energy exchanged continuously between the different electric and magnetic fields associated with the operation of the electrical system and of all the connected apparatus. [601-01-20] 3.1.1.25 short-circuit power The product of the current in the short circuit at a point of a system and a conventional voltage, generally the operating voltage. [601-0-14] 3.1.1.26 transformation of electricity The transfer of electricity through a power transformer. [601-01-08] 3.1.1.27 transmission of electricity The transfer in bulk of electricity, from generating stations to areas of consumption. [601-01-09] 3.1.1.28 voltage level One of the nominal voltage values used in a given system. [601-01-25] 3.1.2 System configuration [60142] 3.1.2.1 branch line; spur feeder An electric line connected to a main line at a point on its route. [601-02-10] NOTE A branch line which is a final circuit is called a spur. 3.1.2.2 duplicate supply A supply to a load by two circuits which are considered to be independent of each other in terms of security of supply. [601-02-19] 3.1.2.3 feeder An electric line originating at a main substation and supplying one or more secondary substations. [601-02-08]

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3.1.2.4 impedance earthed (neutral) system A system whose neutral point(s) is (are) earthed through impedances to limit earth fault currents. [601-02-26] 3.1.2.5 isolated neutral system A system where the neutral point is not intentionally connected to earth, except for high impedance connections for protection or measurement purposes. [601-02-24] 3.1.2.6 link in a system A branch between two nodes of a system. [601-02-07] NOTE It generally comprises a line, a transformer or a connection between two adjacent busbars. 3.1.2.7 mesh (of a system) An arrangement of electric lines forming a closed loop and supplied from several supply sources. [601-02-14] 3.1.2.8 meshed system A system or part of system consisting of multiple meshes. [601-02-17] 3.1.2.9 neutral point connection The means of electrical connection of the neutral point to earth. [601-02-23] 3.1.2.10 neutral point in a polyphase system The common point of the «windings in star-connected equipment such as a power transformer, or an earthing transformer. [601 -02-22] 3.1.2.11 radial system A system or part of a system consisting of single feeders supplied from a single source of supply. [601 -02-15] 3.1.2.12 resonant earthed (neutral) system; arc-suppression- coil-earth (neutral) system A system in which one or more neutral points are connected to earth through reactances which approximately compensate the capacitive component of a single-phase-to-earth fault current. [601-02-27] 3.1.2.13 ring feeder An arrangement of electrical lines forming a complete ring and supplied only from a single source. [601-02-13] NOTE A ring can be operated open or closed. 3.1.2.14 single feeder; radial feeder An electric line supplied from one end only. [601-02-09] 3.1.2.15 single-line diagram A system diagram in which the polyphase links are represented by their equivalent single line. [601 -02-04] 3.1.2.16 single supply A supply given to a load by one circuit only. [601-02-18]

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3.1.2.17 solidly earthed (neutral) system A system whose neutral point(s) is (are) earthed directly. [601-02-25] 3.1.2.18 standby supply A supply which can be used when the normal supply becomes unavailable or inadequate. [601-02-20] 3.1.2.19 supply service; line connection A branch line from the distribution system to supply a consumer's installation . [601-02-12] 3.1.2.20 system configuration A permanent or temporary grouping of similar or dissimilar individual system patterns. [601-02-06] 3.1.2.21 system diagram A topological representation of a system in which the information content depends on a specific requirement. [601-02-01] 3.1.2.22 system operational diagram; operating diagram A system diagram representing a particular operational condition. [601-02-02] 3.1.2.23 system pattern A repetitive arrangement of the nodes in a system and their connections, e.g. feeder, ring, mesh, etc.. [601-02-05] 3.1.2.24 tapped (tee off) substation A single supply substation fed from a single branch line. [601-02-21] 3.1.2.25 teed feeder A main line to which branch lines are connected. [601-02-11] 3.1.2.26 teed system A modified radial system to which spurs have been added. [601-02-16] 3.1.2.27 three-phase system diagram A diagram of a three-phase system in which all phase and neutral conductors are each represented by separate lines. [601 -02-03] 3.1.3 Equipment [60143] 3.1.3.1 electric line; line An arrangement of conductors, insulating materials and accessories for transferring electricity between two points of a system. [601-03-03] 3.1.3.2 gas-insulated line An electric line whose conductors are contained in an enclosure and insulated with a compressed gas. [601-03-06] 3.1.3.3 neutral The designation of any conductor, any terminal or any element connected to the neutral point of a polyphase system. [601-03-10]

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3.1.3.4 overhead earth wire; ground-wire (USA) A conductor connected to earth or lightly insulated, usually installed above the phase conductors of a line or a substation to protect them from lightning strikes. [604-03-48] 3.1.3.5 overhead line An electric line whose conductors are supported above ground, generally by means of insulators and appropriate supports. [601-03-04] 3.1.3.6 overhead system A system consisting essentially of overhead lines. [601-03-07]

NOTE Certain overhead lines can also be constructed with insulated conductors. 3.1.3.7 phase The designation of any conductor, bundle of conductors, terminal, winding or any other element of a polyphase system, which is intended to be energized under normal use. [601-03-09] 3.1.3.8 pole (of a d.c. system) The designation of a conductor, terminal or any other element of a d.c. system which is likely to be energized under normal conditions; e.g. positive pole, negative pole. [601-03-1] 3.1.3.9 pole (of equipment) In certain types of equipment such as switchgear, the part corresponding to one of the phases in AC or to one of the polaries in DC . [601 -03-11]

NOTE According to the number of poles within the equipment, it is called: single-pole equipment, two-pole equipment, etc.. 3.1.3.10 power station; electrical generating station An installation whose purpose is to generate electricity and which includes civil engineering works, energy conversion equipment and all the necessary ancillary equipment. [601-03-01] 3.1.3.11 substation (of a power system) A part of an electrical system, confined to a given area, mainly including ends of transmission or distribution lines, electrical switchgear and controlgear, buildings and transformers. A substation generally includes safety or control devices (for example protection). [601-03-02]

NOTE The substation can be qualified according to the designation of the system of which it forms a part. Examples: transmission, substation (transmission system), distribution substation, 400 kV or 20 kV substations. 3.1.3.12 underground cable; cable an electric line with insulated conductors buried directly in the ground, or laid in cable ducts, pipes, troughs, etc. [601-03-051

NOTE The same expression is used to describe the item physically. 3.1.3.13 underground system A system consisting essentially of underground cables. [601-03-08] 3.1.4 High-voltage d.c. systems [601-04] 3.1.4.1 bipolar d.c. link A link having two poles normally operating at d.c. voltages of opposite polarity in relation to earth. [601-04-03]

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3.1.4.2 high-voltage d.c. link; HVDC link An installation for transmitting large quantities of electricity at high-voltage DC, including the converter substations. [601-04-01]

NOTE In this context, high voltage includes medium, extra-high and ultra-high voltages. [non-lEC note] 3.1.4.3 monopolar d.c. link A link having only one energized pole whatever the means of return of the d.c. current. [601-04-02] 3.2 Generation [602] 3.2.1 Power stations [602-01] 3.2.1.1 generation system The total means of generation in a system. [602-01 -02]

NOTE One can also consider only one given subgroup (thermal generation system for example). 3.2.1.2 hydroelectric installation An ordered arrangement of civil engineering structures, machinery and plant designed chiefly to convert the gravitational potential energy of water into electricity. [602-01-03] 3.2.1.3 hydroelectric power station A power station in which the gravitational energy of water is converted into electricity. [602-01 -04] 3.2.1.4 power station An installation whose purpose is to generate electricity and which includes civil engineering works, energy conversion equipment and all the necessary ancillary equipment. [602-01-01] 3.2.1.5 pumped storage The operation whereby water is raised by means of pumps and stored for later use in one or more hydroelectric installations for the generation of electricity. [602-01-091

3.2.1.6 pumped storage power station A hydroelectric power station employing high level and low level reservoirs permitting repeated pumping and generating cycles to be carried out. [602-01-1 0] 3.2.1.7 run-of-river power station A hydroelectric power station which uses the river flow as it occurs, the filling period of its own reservoir by the cumulative water flows being practically negligible. [602-01-05]

3.2.2 Installation and generation equipment [602-02 ] 3.2.2.1 auxiliary transformer of a unit (of a power station ) A transformer supplying auxiliaries of a unit (of a power station). [602-02-32/33] 3.2.2.2 boiler An installation whose function is to vaporize water under pressure, to superheat - and, in some cases, reheat the steam. [602-02-34] 3.2.2.3 common auxiliaries A group of auxiliary equipment which is common to the unit and the power station. Examples: lighting, compressors. [602-02-30]

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3.2.2.4 A gas turbine set A thermal generating set in which the prime mover consists of a gas turbine. [602-02-23] 3.2.2.5 generating set A group of rotating machines transforming mechanical or thermal energy into electricity. [602-02-01] 3.2.2.6 unit auxiliaries Any auxiliary equipment specific to the unit and indispensable for its operation. Examples: mills, circulating pumps, induced draught fans. [602-02-29] 3.2.2.7 unit generator transformer; set transformer A transformer connected to the generator terminals and through which output power of the generating set is transmitted to the system. [602-02-31] 3.2.3 Operation of power stations [602-03] 3.2.3.1 cold reserve The total available capacity of generating sets in reserve for which the starting up may take several hours. [602-03-17] 3.2.3.2 cold start-up of a thermal generating set The process by which the generating set is raised to speed, the machine connected to the system and loaded after a long period of being out of operation. [602-03-01] 3.2.3.3 economical load of a unit The load corresponding to the minimum of the curve of the heat rate as a function of the load. [602-03-23]

3.2.3.4 hot stand-by All the means of generation ready to start-up for prompt coupling to the system. [602-03-16]

3.2.3.5 hot start-up of a thermal generating set The process by which the generating set is raised to speed, the machine connected to the system and loaded after a short period of being out of operation which did not change the turbine thermal state very much. [602-03-02]

3.2.3.6 isolation of a unit The emergency measure consisting of the disconnection of a unit to maintain the supply of its own auxiliaries. [602-03-28]

3.2.3.7 maximum capacity of a unit (a power station) The maximum power that could be generated by a unit (power station), under continuous operation with all of its components in working order. [602-03-08] NOTE This power may be gross or net.

3.2.3.8 minimum safe output of the unit The power level below which a unit cannot be maintained in continuous service without risk to, at least, one of its components. [602-03-03] 3.2.3.9 power demand from the system The power which has to be supplied to the system in order to meet the demand. [602-03-13]

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3.2.3.10 spinning reserve of a system The difference between the total available capacity of all generating sets already coupled to the system and their actual loading. [602-03-15] 3.3 Power system planning and management [603] 3.3.1 Stability [603-03] 3.3.1.1 self-synchronization The process of synchronization of an unloaded and unexcited synchronous machine that is excited either at the same time as it is coupled to the system or shortly afterwards. [603-03-19] 3.3.1.2 synchronization of two systems The matching of two systems with respect to their frequency and to their voltage magnitude and voltage phase for interconnection purposes. [603-03-18] 3.3.1.3 synchronous operation of a machine The ideal operating condition of a synchronous machine connected to the network in which the electrical angular velocity of the machine corresponds with the network frequency. [603-03-13] NOTE Under practical operating conditions, the angular velocity of the machine may oscillate slightly around the ideal value. 3.3.1.4 synchronous operation of a system The condition of a system in which all machines are in synchronous operation. [603-03-14] 3.3.2 Power system control [603-04] 3.3.2.1 base load set A generating set whose purpose is to nun on continuous duty under operating conditions approaching full load for as long as that operation mode is economical. [603-04-20] 3.3.2.2 controllable load The load of particular consumers which, under contract, must be reduced for a limited period of time, at the request of the distribution supply undertaking. [603-04-42] 3.3.2.3 controllable set A generating set whose purpose is to nun at load levels varying according to the needs of the network supplied as long as that operational mode is economical. [603-04-21] 3.3.2.4 control range (of a generating set) The specified range of active power within which a power-controlled generating set must be able to operate. [603-04-19] 3.3.2.5 generation schedule The scheduling of generation facilities for a specified period. [603-04-02] 3.3.2.6 interruptible load The load of particular consumers which, according to contract, can be disconnected by the supply undertaking for a limited period of time. [603-04-41]

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3.3.2.7 load shedding The process of deliberately disconnecting preselected loads from a power system in response to an abnormal condition in order to maintain the integrity of the remainder of the system. [603-04-32] 3.3.2.8 network splitting; islanding (USA) An emergency measure comprising the division of a power system into subsystems in each of which there is an attempted balance between generation and load to achieve isolated operation. [603-04-31] 3.3.2.9 peak load set A generating set whose purpose is to nun under discontinuous load conditions and to respond rapidly to peaks in the power demand of the network. [603-04-22] 3.3.2.10 power/frequency control Secondary control of the active power of generating sets in response to variations in system frequency and to the variations in the grand total of active power exchanged with the interconnected systems. [603-04-06] 3.3.2.11 primary control (of the speed of generating sets) The control of the speed of each generating set by its individual governor which ensures that the driving torque — is a function of the system frequency. [603-04-04] 3.3.2.12 reactive-power voltage control Voltage control by the adjustment of reactive power generation in a power system. [603-04-27] 3.3.2.13 secondary control (of active power in a system) Co-ordinated control of the active power supplied to the network by particular generators. [603-04-05] 3.3.2.14 system demand control The control of the power demand of the consumers on a power system. [603-04-03] 3.3.2.15 voltage control The adjustment of the network voltages to values within a given range. [603-04-23] 3.3.3 Power system reliability [603-05] 3.3.3.1 availability The state of an item of being able to perform its required function. [603-05-04] 3.3.3.2 forced outage Outage due to the unscheduled putting out of service of an item. [603-05-08] 3.3.3.3 interruption of supply The loss of supply to one or several consumers. [603-05-11] 3.3.3.4 outage; unavailability The state of an item of being unable to perform its required function. [603-05-05] 3.3.3.5 planned outage; scheduled outage Outage due to the programmed taking out of service of an item. [603-05-071

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3.3.3.6 reinforcement of a system Addition or substitution of some items in a power system (transformers, lines, generators, etc.) so that it will be able to meet an increased load or provide a better quality of supply. [603-06-12] 3.4 Operation [604] 3.4.1 Quality of supply [604-01] 3.4.1.1 Consumer A user of electricity provided by an electricity supply system, generally a distribution system. [604-01-03] 3.4.1.2 distribution undertaking An organization supplying electricity to a group of consumers by means of a distribution system. [604-01 -02] 3.4.1.3 quality of supply An appraisal of the deviations of technical criteria outside a defined range (explicit or implicit) of the electricity supply or of the aggregate of electricity supplies within an electrical system. [604-01-05] 3.4.1.4 supply disconnection The interruption of supply over a significantly long period of time, due to the opening of a switching device. [604-01 -34] 3.4.1.5 supply (of electricity) A public service provided by a distribution undertaking to any consumer and determined according to technical and commercial criteria such as frequency, voltage, continuity, maximum demand, point of supply, tariffs. [604-01-01] 3.4.1.6 supply voltage The voltage which a distribution undertaking maintains at the consumer's point of supply. [604-01-16] NOTE If a supply voltage is specified, for instance in the supply contract, then it is called "declared (supply) voltage". 3.4.2 Faults [604-02] 3.4.2.1 automatic reclosing The automatic reclosing of a circuit-breaker associated with a faulted section of a network after an interval of time which permits that section to recover from a transient fault. [604-02-32] 3.4.2.2 closing The closing of a circuit-breaker by either manual or automatic control of protective devices. [604-02-30] NOTE The expression "closing" of a network item (line, transformer) in fact means closing of the associated circuit-breakers. 3.4.2.3 disturbance recorder; perturbograph An instrument in continuous operation, provided with a memory making it possible to record events and transient variables before and during fault conditions. [604-02-43] 3.4.2.4 fault An unplanned occurrence or defect in an item which can result in one or more failures of the item itself or of other associated equipment. [604-02-01]

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3.4.2.5 fault locator A device used for fault location. [604-02-42] 3.4.2.6 final tripping; lock-out The disconnection of faulty equipment or of part of the network after a predetermined number of unsuccessful reclosures. [604-02-39] 3.4.2.7 incident An event of external or internal origin, affecting equipment or the supply system and which disturbs its normal operation. [604-02-03] 3.4.2.8 intermittent fault A transient fault which recurs repeatedly in the same place and due to the same cause. [604-02-14] 3.4.2.9 load transfer A redistribution of load flow within similar components of the network, due to the failure or risk of failure, of a part of the network. [604-02-40] 3.4.2.10 maloperation; misoperation Performance of a device different from that which would be expected. [604-02-05] 3.4.2.11 opening; tripping The opening of a circuit-breaker by either manual or automatic control of protective devices. [604-02-31] NOTE The expression tripping of a network item (line, transformer) in fact means tripping of the associated circuit-breakers. 3.4.2.12 permanent fault A fault which affects a device and prevents its restoration into service until action has been taken at the point of the fault. [604-02-10] 3.4.2.13 transient fault An insulation fault which only temporarily affects a device's dielectric properties which are restored after a short time. [604-02-11] 3.4.3 Safety [604-04] 3.4.3.1 earth electrode; ground-electrode (USA) A conductor or group of conductors in intimate contact with and providing an electrical connection to earth. [604-04-03] 3.4.3.2 earthing system; grounding system (USA) An arrangement of connections and devices necessary to earlh equipment or a system separately or jointly. [604-04-02] 3.4.3.3 earth terminal; ground terminal (USA) A terminal fitted on equipment and providing a means of connection for an earth conductor. [604-04-08] 3.4.3.4 insulated tool A tool made of conductive material and fully or partly covered by insulating material. [604-04-29 modified]

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3.4.3.5 insulating pole An insulating tool made of insulating tube and/or rod with end fittings. [604-04-31 modified] 3.4.3.6 insulating tool A tool essentially made of insulating material. [604-04-30] 3.4.3.7 live working A generic term indicating the various working methods used to carry out maintenance, including connection and disconnection operations on electrical installations while in service. [604-04-25] 3.4.3.8 operational earthing; operational grounding (USA) The earthing of a point in the electrical circuit of equipment (e.g. the neutral point) which is necessary for correct operation of this equipment and/or the system. [604-04-12] 3.4.3.9 safe clearance working; hot stick working (USA) The method of live working by which the worker remains at a specified distance from the live parts and carries out his work by means of insulating poles. [604-04-26] 3.4.3.10 to earth (equipment, an installation or a system); to ground (USA) To effect the necessary connections in order to maintain a given point of equipment, an installation or a system as close as practicable to earth potential. [604-04-01] 3.4.3.11 working pole; working stick An insulating tool made of insulating tube and/or rod with end fittings. [604-04-31] 3.5 Substations [605] 3.5.1 Types of substations — Substation layouts [60 5-01] 3.5.1.1 attended substation A substation which is operated by personnel during the normal working hours and otherwise as necessary. [605-01 -12] 3.5.1.2 converter substation A substation including converters and the main function of which is to convert alternating current into direct current or vice versa. [605-01-07] 3.5.1.3 double busbar substation A substation in which the lines and transformers are connected via two busbars by means of selectors. [605-01-17]

3.5.1.4 frequency converter substation A substation in which an a.c. current at a given frequency is converted into an a.c. current at another frequency. [605-01-08]

3.5.1.5 manned substation A substation which is locally operated by personnel working within the substation. [605-01 -09] 3.5.1.6 master substation A manned substation from which remotely controlled substations are controlled. [605-01-14]

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3.5.1.7 mesh substation A single busbar substation in which the busbar is formed as a closed loop with circuit-breakers in series within the loop. [605-01 -20] 3.5.1.8 permanently manned substation A substation which is continuously controlled by personnel who are stationed at the substation. [605-01 -11] 3.5.1.9 remotely controlled substation An unmanned substation which is controlled by means of telecontrol devices. 1605-01 -131 3.5.1.10 ring substation A single busbar substation in which the busbar is formed as a closed loop with only disconnectors in series within the loop. [605-01-19] 3.5.1.11 satellite substation One of the remotely controlled substations, controlled by a master substation. [605-01-15] 3.5.1.12 single busbar substation A substation in which the lines and transformers are connected to one busbar only. [605-01-16] 3.5.1.13 step-down substation A transformer substation in which the outgoing power from the transformers is at a lower voltage than the incoming power. [605-01-05] 3.5.1.14 step-up substation A transformer substation in which the outgoing power from the transformers is at a higher voltage than the incoming power. [605-01 -04] 3.5.1.15 substation (of a power system) The part of a power system, concentrated in a given place, including mainly the terminations of transmission or distribution lines, switchgear and housing and which may also include transformers. It generally includes facilities necessary for system security and control (e.g. the protective devices). [605-01-01]

NOTE According to the nature of the system within which the substation is included, a prefix may qualify it.

Examples: transmission substation (of a transmission system), distribution substation, 400 kV substation, 20 kV substation. 3.5.1.16 switching substation A substation which includes switchgear and usually busbars, but no power transformers. [605-01-02] 3.5.1.17 traction substation A substation, the main function of which is to supply a traction system. [605-01-06] 3.5.1.18 transformer substation A substation containing power transformers interconnecting two or more networks of different voltages. [605-01-03]

3.5.1.19 triple busbar substation A substation in which the lines and transformers are connected via three busbars by means of selectors. [605-01-18]

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3.5.1.20 unmanned substation A substation which is operated by personnel who are not stationed at the substation. [605-01-10] 3.5.2 Primary plant of substations [605-02] 3.5.2.1 auxiliary transformer In a substation, a transformer intended to provide supply to the auxiliary equipment. [605-02-46] 3.5.2.2 bay (of a substation) The part of a substation within which the switchgear and controlgear relating to a given circuit are contained. [605-02-09]

NOTE According to the type of circuit, a substation may include: feeder bays, transformer bays, bus coupler bays, etc.. 3.5.2.3 busbar A low impedance conductor to which several electric circuits can be separately connected. [605-02-01] 3.5.2.4 bus coupler circuit-breaker In a substation a circuit-breaker which is located between two busbars and which permits the busbars to be coupled; it may be associated with selectors in case of more than two busbars. [605-02-40] 3.5.2.5 earthing switch In a substation, a special disconnector which is intended to connect phase conductors to earth for safety purposes. [605-02-43] 3.5.2.6 feeder bay In a substation, the bay relating to a feeder or a link to a transformer, a generator or another substation. [605-02-10] 3.5.2.7 feeder circuit-breaker In a substation, a circuit-breaker which is located within a feeder bay and through which a feeder can be energized. [605-02-38] 3.5.2.8 feeder disconnector A disconnector which is located in series at the end of a feeder, within a substation bay, in order to isolate the feeder from the system. [605-02-44] 3.5.2.9 indoor substation A substation sheltered from external weather conditions by being installed within a building. [605-02-15] 3.5.2.10 kiosk substation A compact substation, often prefabricated and used only for distribution purposes. 1605-02-17] 3.5.2.11 main busbar In a double (or triple) busbar substation, any busbar which is used under normal conditions. [605-02-03] 3.5.2.12 open-type substation A substation in which the insulation to earth and between phase conductors is mainly provided by air at atmospheric pressure and in which some live parts are not enclosed. [605-02-13]

NOTE An open-type substation may be indoor or outdoor.

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3.5.2.13 outdoor substation A substation which is designed and installed to withstand external weather conditions. [605-02-16] 3.5.2.14 outgoing (incoming) feeder In a substation, a feeder bay which is normally used to transmit power to the system (receive power from the system). [605-02-11/12] 3.5.2.15 pole-mounted substation An outdoor distribution substation mounted on one or more poles. [605-02-19] 3.5.2.16 reserve busbar In a double (or triple) busbar substation, any busbar which is used under abnormal conditions. It is generally less well equipped than a main busbar. [605-02-04] 3.5.2.17 selector switch disconnector In a double or triple busbar substation, a disconnector which is intended to connect a primary circuit (line, transformer, etc.) to one of the busbars. [605-02-42] 3.5.2.18 transformer circuit-breaker In a substation, one of the circuit-breakers located on each side of a transformer and which is usually designated by the corresponding voltage level. [605-02-39] 3.5.2.19 working clearance The minimum safe distance to be observed between normally exposed live parts and any person working in a substation. [605-02-25] 3.5.3 Secondary arrangements of substations [605-03 ] 3.5.3.1 auxiliary switchboard A panel (or a cubicle) on which are fixed the devices necessary to control, to protect and to distribute auxiliary a.c. and d.c. supplies withhin a substation. [605-03-11] 3.5.3.2 control board (desk) A board (desk) on which are fixed control devices which are necessary to control and/or display a substation or a system. [605-03-01/02] 3.5.3.3 mimic diagram; wall diagram An arrangement of symbols representing the current state of switchgear and lines of a substation (network) and which may be updateable and may have control functions. [605-03-03] 3.5.3.4 visual display unit A unit comprising devices which are necessary to display information required and, possibly to include an acknowledgement facility. [605-03-04]

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3.6 Definitions not in chapters 601, 602, 603,604 a nd 605 of IEC 60050 3.6.1 Definitions with regard to Occupational Healt h and Safety 3.6.1.1 point of control The point at which the electrical installation on or in any premises can be switched off by a user or lessor from the electricity supplied from the point of supply 3.6.1.2 point of supply The point at which electricity is supplied to any premises by a supplier 3.6.2 Personnel and procedures 3.6.2.1 appointed operator An employee who has been authorized in writing to carry out switching, isolating, safety testing and earthing operations in terms of the relevant high voltage operating regulations. 3.6.2.2 approved Acceptable to, and approved in writing by the person in charge of the system. 3.6.2.3 authorized operation An operation authorized by the system controller or superintendent. 3.6.2.4 authorized person A person who has, in writing, been delegated defined authority and responsibilities in terms of the relevant high voltage operating regulations. 3.6.2.5 commissioning The formal procedure for the addition of apparatus or systems to the existing system. 3.6.2.6 competent person A person who is in possession of a competency certificate for the classes of work in which he is deemed to be competent to work without constant supervision. 3.6.2.7 control officer; control superintendent; controller An employee or official on duty at a control centre, who is responsible for the general operation of the power system or of a section thereof. 3.6.2.8 emergency switching The opening, only, of such circuit-breakers or switches as may be necessary to avoid imminent danger to life or damage to apparatus. 3.6.2.9 in commission The state of any apparatus in the normal operating mode, or available for immediate use. (See also 3.3.3.1.) 3.6.2.10 isolate To disconnect from all possible sources of electrical potential NOTE In this context apparatus may be isolated by the

opening or removing (or both) of fuses;

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opening of isolators; removing of jumpers; opening of air-break switches; withdrawal of truck type switchgear; immobilization of circuit-breakers that have visible contact separation and that are not fitted with grading capacitors; and utilization of an approved change-over circuit-breaker or isolator.

3.6.2.11 lock-out The state of an auto-recloser when it has completed its tripping and closing sequence and is in its final open state. 3.6.2.12 log book A book in which all operating or testing procedures or faults are recorded for future reference. 3.6.2.13 made safe De-energized or isolated and earthed as required to allow the necessary work to be carried out without danger. 3.6.2.14 operating Switching, isolating, safety testing, or earthing. 3.6.2.15 operating diagram The wall diagram or electronic diagram in a control centre or control room to indicate the operating position and status of all apparatus. 3.6.2.16 operating instruction form The printed form used to record the operating instructions that are issued by the controller and that are related to the operation of electrical apparatus. 3.6.2.17 operating procedure form The printed form used to record the operating instructions that are authorized by the controller and that are related to the operation of electrical apparatus. 3.6.2.18 out of commission The state of any apparatus that has been taken out of service and is not available for immediate use. (See also 3.3.3.4.) 3.6.2.19 prohibited area An enclosed area, in which live conductors or live parts of electrical apparatus are accessible, and to which access is restricted to specifically authorised persons. 3.6.2.20 regulation (See IEC 50-441 and IEC 50-551). 3.6.2.21 responsible person A person who has been authorized in writing to be responsible for ensuring that the work on the electrical apparatus can be carried out with safety. 3.6.2.22 switching The opening or closing of circuit-breakers or switches on links in a system.

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3.6.2.23 trainee authorized person A person who has been authorized in writing to carry out switching, isolating, testing and earthing procedures on defined apparatus or equipment under the instruction of the controller, and under direct supervision of an authorized person. 3.6.2.24 warning notice A portable notice provided to indicate that work is in progress on a supply system or apparatus or to indicate any special operating conditions in force on any panel or circuit, or to indicate both. 3.6.2.25 work permit The document(s) for the authorization of all work to be done on any supply system or apparatus.

NOTE A work permit can include the application, permit, clearance and workmen's declaration documents. 3.6.3 Networks and substations 3.6.3.1 airbreak switch A device used for the purpose of connecting, sectionalizing or isolating equipment or sections of overhead line. 3.6.3.2 apparatus Any transformer, motor, circuit-breaker, switch, link, feeder, test equipment, electrified fence or any other LV/MV/HV plant installed in a substation, feeder or system. 3.6.3.3 barrier/barricade Any device designed to restrict approach to live electrical apparatus, excavations or other dangerous conditions. 3.6.3.4 bulk supply A supply to a consumer's substation at a voltage of 80 kV or higher. 3.6.3.5 bus coupler A circuit-breaker designed to connect or disconnect two busbar sections in parallel. 3.6.3.6 bus section circuit-breaker A circuit-breaker designed to connect or disconnect two busbar sections in series. 3.6.3.6(a) bus section isolator An isolator designed to connect or disconnect two busbar sections in series. 3.6.3.7 chamber An enclosure in which high voltage apparatus is separated from other apparatus by partition walls or other means and the access to which is restricted by interlocks. 3.6.3.8 circuit An arrangement of conductors and apparatus for the purpose of carrying electrical energy. 3.6.3.9 circuit-breaker A mechanical switching device capable of making, carrying and breaking currents under normal circuit conditions and also making, carrying for a specified time, and breaking currents under specified abnormal conditions, such as those of a short-circuit. [IEC 50-441-14-20]

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3.6.3.10 circuit earth That part of a circuit that is or can be connected directly to earth. 3.6.3.11 circuit-side The side of a circuit-breaker or switch that contains the cable or circuit connections, and that can be isolated from the busbars. 3.6.3.12 close proximity Beyond a position in which any part of a person or tool being used could inadvertently encroach within the minimum safe clearance (of any bare, live parts). 3.6.3.13 consumer's substation A substation owned and operated by a consumer to distribute electrical energy around his premises. NOTE The electricity supply authority responsibility ends at the point of supply. 3.6.3.14 control panel; panel The panel on which control switches and other equipment are mounted for controlling the operation of the apparatus. 3.6.3.15 current transformer An instrument transformer in which the secondary current, in normal conditions of use, is substantially proportional to the primary current and differs in phase from it by an angle which is approximately zero for an appropriate direction of the connections. [IEC 321-02-01]. 3.6.3.16 dead At or about zero potential and disconnected or isolated from any live power system.

NOTE Rotating plant should not be regarded as dead until it is stationary or being slowly rotated by means of barring gear and it is not excited. 3.6.3.17 de-energized Disconnected from any live system. 3.6.3.18 discharge The controlled removal of electric charge, and thereafter the verification of the absence of charge. 3.6.3.19 distribution network/system All apparatus installed for the distribution of electrical energy. 3.6.3.20 distribution transformer A voltage step-down transformer to supply a section of a distribution network with electrical energy. 3.6.3.21 fuse-switch A switch in which a fuse-link or a fuse-carrier with fuse-link forms the moving contact. [IEC 441 -14-17] 3.6.3.22 gas-insulated switchgear (GIS) Switchgear which is totally enclosed and whose conductors and busbars are insulated by an inert gas such as sulfur hexafluoride (SF6).

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3.6.3.23 generating station A building that contains the necessary equipment for generating electrical energy. 3.6.3.24 high-voltage yard; HV yard An enclosure that contains exposed overhead medium voltage, high voltage; extra-high voltage or ultra-high voltage components. 3.6.3.25 instrument transformer A transformer specially designed to maintain a certain relationship in phase and magnitude between the primary and secondary voltages or currents. 3.6.3.26 isolator The device provided for the purpose of isolating apparatus from the source of electrical energy. 3.6.3.27 link See isolator (3.6.3.26).

NOTE The term link is deprecated by the IEC, and the term isolator should rather be used. 3.6.3.28 live enclosure; live chamber Any chamber or enclosed area that contains medium voltage, high voltage; extra-high voltage or ultra-high voltage apparatus which might be unscreened and could be alive. 3.6.3.29 main earth An earthing device applied as part o1 the requirement for the issue of a permit to work. 3.6.3.30 mains The cables or overhead lines forming part of the reticulation network. 3.6.3.31 main substation Any transformer a switching station (or both) on the distribution system. 3.6.3.32 off load switching device A switch that is only capable of making or breaking a circuit when no current is flowing. 3.6.3.33 on load switching device A switch that is capable of making and breaking a limited flow of electric current. 3.6.3.34 out of commission The state of any apparatus that has been taken out of service and is not available for immediate use. (See also 3.3.3.4.)

3.6.3.35 point of control The point within the consumer's own installation where a switch or circuit-breaker is located which can be used to isolate all other switches, circuit-breakers and bad on the consumer's installation from the supply system.

3.6.3.36 point of metering That point on a distribution or reticulation network at which the metering, or the current and voltage transformers supplied for metering, are located.

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3.6.3.37 reticulation system A distribution network/system for a specific local distribution area. 3.6.3.38 ring main See ring feeder (3.1.2.13). NOTE A ring can be operated open or closed. [602-03-13] 3.6.3.39 ring main switchboard A single busbar switchboard that can supply a reticulation network and can open or close a section of a ring main. 3.6.3.40 ring main unit A completely enclosed single busbar trunk which forms part of the ring main and contains one or more branch switches. 3.6.3.41 screened (equipment) Completely surrounded by earthed metal or protected from accidental contact by a fixed barrier of non-conducting material. 3.6.3.42 sectionalizing switch A switch provided on overhead lines for use in conjunction with an auto-reclosing circuit-breaker for the automatic disconnection of faulty sections of overhead line whilst the line is dead. 3.6.3.43 selector switch A switching device capable of making, carrying and breaking current, combining the duties of a tap selector and a diverter switch. [IEC 50-421-11-04] 3.6.3.43(a) series capacitor A device for reducing the impedance of a line to improve the load transfer. 3.6.3.43(b) series reactor A device used for limiting the fault current. 3.6.3.43(c) shunt capacitor A device for generating reactive power for voltage control. 3.6.3.43(d) shunt reactor A device used for absorbing reactive power for voltage control. 3.6.3.43(e) static reactive power compensator A device used for automatic reactive power control, for compensator voltage control and for balancing the three phases. 3.6.3.44 switch A mechanical switching device capable of making fault current and carrying and breaking load current. 3.6.3.45 switchboard Two or more switch panels with their interconnecting busbars.

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3.6.3.46 switch chamber; switch room A chamber or room that contains switchgear. 3.6.3.47 switch panel All the apparatus comprising any one circuit of a switchboard, including the busbar and the connection to the cable. 3.6.3.48 switch yard Any outdoor enclosed area that contains switchgear. 3.6.3.48(a) synchronous condenser A synchronous machine used for reactive power control. 3.6.3.49 system An electrical system in which all the conductors and devices are electrically connected to a common source of electrical energy. 3.6.3.50 transformer A static item of apparatus used to transform or regulate voltage, including all conductors permanently connected to its terminals. (See also IEC 50-421.) 3.6.3.50(a) transfer bus coupler A circuit-breaker used either for connecting two sets of busbars or for putting a feeder on transfer. 3.6.3.50(b) transfer circuit-breaker A circuit-breaker used to energize the transfer busbar when putting a feeder on transfer. NOTE A transfer busbar is sometimes provided at EHV substation. It is a busbar in addition to the normal substation busbars, to which feeders can be connected temporarily, usually for the purpose of maintenance. The operation required to connect a feeder to the transfer busbar is known as "putting a feeder on transfer". 3.6.3.51 transmission line An overhead power line to transfer large amounts of electrical energy. 3.6.3.52 transmission system All the medium voltage, high voltage, extra-high voltage or ultra-high voltage apparatus installed for the transmission and transformation of electrical energy, including the switchboards at major substations. 3.6.3.53 unit protection An apparatus that is able to detect a fault in a predefined section of the power system and that under fault conditions causes one or more circuit-breakers to disconnect the faulty section. 3.6.3.53(a) voltage regulator A device used for automatic voltage control at a pre-set voltage. 3.6.3.54 voltage transformer An instrument transformer in which the secondary voltage, in normal conditions of use, is substantially proportional to the primary voltage and differs in phase from it by an angle which is approximately zero for an appropriate direction of the connections. [IEC 60050-321]

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3.6.4 Safety equipment and safety methods 3.6.4.1 alive; live Electrically charged. 3.6.4.2 back up protection Protection equipment or system which is intended to operate when a system fault is not cleared in due time because of inability or failure of the main protection to operate, or in the case of failure to operate of a circuit-breaker other than the associated circuit-breaker. [IEC 60050-448] 3.6.4.3 earthed So connected to the general mass of earth as to ensure an immediate safe discharge of electrical energy . 3.6.4.4 earthing gear; earthing device A fixed or portable appliance used for earthing electrical apparatus. 3.6.4.5 earthing label The printed form or label attached to an apparatus to indicate that it has been earthed. 3.6.4.6 enclosure Any room, chamber, yard or enclosed area in which it is possible for a person from ground or floor level to make inadvertent contact with, or come into close proximity of, live conductors or apparatus. 3.6.4.7 interlock An electrical, mechanical or electromechanical device to ensure that operations are performed in a pre-determined sequence. 3.6.4.8 keys Keys used to operate safety locks, which are kept in a key safe, and are required for the issue of a work permit. 3.6.4.9 link stick; operating stick An approved insulating rod designed for use at specific voltages to safely operate links, drop-out fuses and other similar equipment. NOTE The term "link" for "disconnector" is deprecated by the IEC. 3.6.4.10 live tester A device used to determine whether a conductor is live or dead by making physical contact with the conductor. 3.6.4.11 main earth An earthing device applied as part of the requirement for the issue of a work permit. 3.6.4.12 portable earthing device Any portable appliance provided for connecting to earth a circuit or apparatus that is isolated.

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KS 1859-1:2010


3.6.4.12(a) safety clearance The minimum distance that, for safety reasons, needs to be maintained between any part of a person's body or any work tool and any unearthed, bare LV conductor or any unearthed and screened MV/HV conductor. NOTE The following safety clearances are specified according to the rated voltage of the system:

Rated voltage (r.m.s. phase-to-phase) Safety cleara nce Upto11kV 0.20m Above11 kV and up to 33 kV 0.43m Above 33 kV and up to 66 kV 0.77 m Above 66 kV and up to 132 kV 1.45m Above 132 kV and up to 275 kV 2.35m Above 275 kV and up to 400 kV 3.20 m Above 400 kV and up to 765 kV 5.50 m

3.6.4.13 safety equipment Any equipment or article, including protective clothing, that is manufactured, provided, installed or used in the interest of safety. 3.6.4.14 safety lock An approved lock or suite of locks for which only one single key is available. 3.6.4.15 safety testing The testing of apparatus to ascertain whether it is live or dead by means of equipment provided for this purpose. 3.6.4.16 shutters Mechanically operated safety covers for, or on, orifices, to prevent access to live parts of switchgear. 3.6.4.17 temporary earth; working earth A supplementary earthing device that is applied at, or within view of, the work site and that is removed before clearance of the permit to work. 3.6.5 Other definitions 3.6.5.1 extra-high voltage (EHV) The set of nominal voltage levels that are used in power systems for bulk transmission of electricity in the range 220 kV < U < 400 kV. 3.6.5.2 high voltage (HV) The set of nominal voltage levels that are used in power systems for bulk transmission of electricity in the range 44 kV < Un < 220 kV. 3.6.5.3 low voltage (LV) The set of nominal voltage levels that are used for the distribution of electricity and whose upper limit is generally accepted to be an a.c. voltage of 1 000 V (or a d.c. voltage of 1 500 V). NOTE In certain fields of technology, for example electric motors and mining, voltages up to and including 1 100 V are traditionally regarded as low voltage. 3.6.5.4 medium voltage (MV) The set of nominal voltage levels that lie above low voltage and below high voltage in the range 1 kV < UL < 44 kV.

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KS 1859-1:2010


3.6.5.5 point of supply The point at which electricity is supplied to any premises by a supplier. 3.6.5.6 ultra-high voltage (UHV) The set of nominal voltage levels that are used in power systems for bulk transmission of electricity in the range UL > 400 kV.

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