Glossary terms beginning with C

Terms used within Transpower
Click one of the letters above to go to the page of all terms beginning with that letter.
Cabinet

An enclosed frame with sides, floor, roof and perhaps door, all designed for an indoor environment to contain and support secondary equipment.

Cable

One or more insulated conductors forming a transmission circuit above or below the ground.

Cable duct

A duct laid in the ground to enclose power, auxiliary and control cables.

Cable rack

A rack supporting cables which are usually arranged to run side by side.

Cadweld

A proprietary name for an exothermic welding technique for jointing conductors.

CAG

This is a group of attributes used in ACI. The grouping is typically based on commonality of use. The attribute group may be related to one or more COB types in ACI. For instance, the LOCATION attribute group is associated with all equipment type COB's like circuit breakers, transformers, disconnectors.

Cap and pin

A term used for a post insulator with metal flanges that may be stacked one on top of another to attain the requisite voltage rating.

Capability diagram

A diagram showing the operating limits of a generator or synchronous condenser.

Capacitor bank

A number of capacitors connected together in series and/or parallel to form the requisite capacitance and voltage rating for reactive compensation and harmonic filters on the HVAC and HVDC power systems.

Capacitor divider

A three terminal device having one terminal (primary) at a high voltage (to be measured ), a second terminal (earth) at or near earth potential and the third terminal (intermediate) at an intermediate voltage. The divider may be made up of a number of individual capacitors bonded together and mounted on a common support structure (Xmas tree) or an encapsulated unit with the capacitors installed inside an oil-filled porcelain housing.

Capacitor voltage transformer

A voltage transformer comprising a capacitor divider unit and an electromagnetic unit (transformer),so designed and interconnected that the secondary voltage of the electromagnetic unit is substantially proportional to and in phase with the primary voltage applied to the capacitor divider unit.

Capacity

The quantity of electricity in ampere hours (A.h.) which a fully charged battery can deliver under specified conditions. The capacity of a cell or battery is denoted by the symbol C. As the capacity varies with the rate of discharge, the symbol C is followed by a numerical suffix giving the rate of discharge. Thus C10 is the capacity in ampere hours (A.h.) at the 10 hour rate of discharge. The specified temperature is usually 25 oC. The final voltage depends on battery type and conditions of service.

carbon footprint

A carbon footprint is an assessment of the greenhouse gases emitted by a particular organisation or project, typically expressed for a 12 month period.  This includes an assessment of the six greenhouse gases addressed under the Kyoto Protocol, and can include other greenhouse gases if desired.  Greenhouse gas (GHG) emissions are described as carbon dioxide equivalents (CO2e); that is, the global warming potential (GWP) of the gas, relative to CO2.

Carryover (communications)

The time period for which the battery can maintain the discharge duty cycle following failure of the charger/rectifier, i.e. from mains failure until minimum equipment distribution voltage (22.5 V) is reached.

Casual intent

Motivation of a person (or persons) who has no right to be accessing the grid operating asset.  They have gained access to the grid operating asset ‘casually’  or  ‘accidentally’. Children (mostly) will fall into this category. They are naïve in gaining casual entry and do not understand possible consequences and implications of what they are doing.

Cathodic protection

The prevention or reduction of corrosion of buried steel grillage by making it act as the cathode in a galvanic or electrolytic cell.

CB

A 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 short circuit.

cct

A telecommunication link for transmitting speech, data, control, and/or protection signals.

CDPR

A progress checklist and sign-off record that is compiled for each controlled document development project.

Cell (battery)

An assembly of electrodes and electrolyte which constitute the basic unit of a battery. Nominally a 2 V block for lead- acid cells.

certificate

A collective term for the access permit and test permit. Under an authorisation, the recipient’s work party is allowed temporary access to defined equipment which has been removed from service and which is in a defined state, to enable work to be undertaken. Note: Entry approval is not an authorisation as defined above.

Certification of design verification

The certificate issued by an inspection body that the design of the pressure equipment or crane has been verified.

Chalking

The appearance of filler particles of the housing material forming a rough powdery surface. This chalking is the result of UV deterioration and/or erosion.

Change to Offer

Advice by telephone of changes to offers (availability, capability or configuration) for today; after 13:00 today, for changes to offers for tomorrow where the changes alter previously advised start or end times or both. Note: changes include forced outage situation where an AFS statement cannot be given within 15 minutes, requiring a CTO (previously an offer was "in-service" by default) complete with an indicative or actual return time.

Charging current (line)

The current taken by a transmission circuit to energise its conductors due to the capacitive effect of the circuit.

Check command (SCADA)

A command for the purpose of ensuring that the SCADA equipment is functioning correctly.

Check valve/non return valve

A valve designed to permit air flow in one direction only and blocks flow in the reverse direction.

CIR

An operational request to a Transpower service centre, asking for acceptance of either: a brief planned interruption of service on communications equipment, or a possibility of interrupting service on communications equipment due to predictable risks.

Circuit (communication)

A telecommunication link for transmitting speech, data, control, and/or protection signals.

Circuit-breaker

A 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 short circuit.

Circuit-breaker bypass disconnector

The functional term for a disconnector that is connected in parallel with a circuit-breaker.

Circuit-breaker bypassing

A procedure used when a circuit-breaker bypass disconnector is closed to carry the circuit-breaker's load current. This enables the circuit-breaker to be isolated for maintenance.

Circuit-breaker control selector switch

A control switch provided within each circuit-breaker operating mechanism cabinet to enable the circuit-breaker to be closed and opened at the circuit-breaker during maintenance and test work, and sometimes to completely disable the circuit-breaker.

Circuit-breaker controller

A manually-operated switch located in the control room at the same site and used to remotely operate a circuit-breaker.

Circuit-breaker disconnector

The functional term for a disconnector that provides a point-of-isolation for a circuit-breaker.

Circuit-breaker fail protector

Backup protection which monitors the performance of a circuit-breaker following a main protection relay operation. Circuit-breaker fail protection trips all other circuit-breakers connected to the same bus (or bus section) if a circuit-breaker fails to open after a trip command from the main protection.

Circuit-breaker lockout

The status of a circuit-breaker deliberately prevented from operating due to the action of a monitoring or protection device.

Circuit-breaker operating mechanism

A mechanism that provides the motive force to operate a circuit-breaker.

Civil defence emergency

An emergency situation of such magnitude that the safety of the public is endangered and the local authority or authorities have invoked the special powers extended to them by the Civil Defence Act. In a civil defence emergency Transpower has specific responsibilities, as defined in Transpower standards.

Clean workshop

A dedicated workshop which is used for the renovation of mercury arc valves, where strict standards of cleanliness are maintained.

Clearance of a fault

The removal from service of a faulted item of equipment by the operation of its protection relays.

Climbable (line supports)

A structure is considered to be climbable when an agile child could, without external aids, gain access to the climbing step height. (This particularly applies to most designs of 110 kV and lower voltage towers and lattice steel poles).

Climbing patrol

A transmission line patrol during which each pole or tower is climbed.

Close

Electrical: to operate a switch, circuit-breaker, disconnector etc so as to permit the flow of an electric current. Mechanical: to operate a gate or valve so as to stop or prevent the passage of a substance.

Closing time (circuit-breaker)

The interval of time between the initiation of the closing operation and the instant when the main contacts touch in all poles.

CM contractor

Transpower's communications maintenance contractor.

CMD

Documents prepared, managed and maintained by the site maintenance contractor. For the requirements of this standard the CMD would cover the relevant site oil information.

Co-generation

The use of high-pressure steam from a turbo-generator set for an industrial process. The production of electricity is usually secondary to the requirements of the industrial process.

COB

This is the main constructor for the ACI application database. All things in the system are COB's. Using consistently defined COB's is a way of generically defining the data structures in ACID so they are flexible and extendable. Examples of COB's are circuit breakers, transformers, disconnectors, outages, branches, PEG's.

Code

The Code sets out participant responsibilities, including the Authority's duties and responsibilities. The Authority maintains the Code and is responsible for ensuring participants comply with the Regulations and the Code.

Coefficient of earthing

The coefficient of earthing at a selected location of a three-phase system for a given system layout is the ratio, expressed as a percentage, of the highest rms line-to-earth power frequency voltage on a sound phase at the selected location during a fault to earth affecting one or more phases, to the line-to-line rms power frequency voltage which would be obtained at the selected location with the fault removed.

COF

confirmation by telephone that a specified grid asst will be removed from or returned to service in accordance with its offer and is the trigger for giving a PTP.

COMIT

(Replaced by WITS)  Commodity Market Information and Trading System. Electronic trading and information system operated by EMCO.

Command intertrip scheme

A protection signalling system whereby protection at one station initiates tripping of a circuit-breaker at another station in order to clear a fault. Required where either: the local protection has to trip a remote circuit-breaker due to the absence of a local circuit-breaker, or the trip of a local circuit-breaker has to be initiated by remote protection due to the absence of local protection.

Commentary

A supporting document which outlines the development history of a controlled document and/or contains proprietary or other information intended for use only by Transpower.

Commerce Commission

The regulatory body with responsibility for regulating Transpower’s operational and capital expenditure.

Commissioned

The operational state of equipment which has undergone the commissioning process and is brought under the operational control of a service centre.

Commissioning

The process to bring new or reinstalled equipment into a state for operation.

Commissioning co-ordinator

The person appointed by the project manager who co-ordinates the construction commissioning activities.

Commissioning plan

A document that is used to plan and control the process of connecting untested equipment to, or withdrawing equipment from, the power system.

Common alarm

An alarm that is initiated by more than one activating device.

Common Attribute Group

This is a group of attributes used in ACI. The grouping is typically based on commonality of use. The attribute group may be related to one or more COB types in ACI. For instance, the LOCATION attribute group is associated with all equipment type COB's like circuit breakers, transformers, disconnectors.

Common auxiliary

Auxiliary equipment which serves more than one unit and/or the power station.

Common Object

This is the main constructor for the ACI application database. All things in the system are COB's. Using consistently defined COB's is a way of generically defining the data structures in ACID so they are flexible and extendable. Examples of COB's are circuit breakers, transformers, disconnectors, outages, branches, PEG's.

Communications equipment

Equipment used primarily for provision of communications services to support the operation or management of the power system. This includes equipment for: voice communications, data transfer, remote control, protection signalling and equipment connected to other communications systems and circuits leased from other communications operators. Note: This includes, but is not limited to, SSB, VHF, UHF, DMR and satellite radio, PLC, leased circuits, carrier cables, fibre optic cables and associated terminals and circuits.

Communications interruption

A momentary interruption to a communications circuit of less than five minutes duration caused by circuit re-routing or maintenance switching that may or may not be caused by on-site maintenance or construction staff.

Communications interruption request

An operational request to a Transpower service centre, asking for acceptance of either: a brief planned interruption of service on communications equipment, or a possibility of interrupting service on communications equipment due to predictable risks.

Communications site

A site with any communications equipment or services connected to a power system communications network and used for the operation or management of the power system.

Commutation failure

An HVDC inverter fault (mercury arc valve or thyristor) usually initiated by an ac disturbance, where current fails to transfer from one valve to the next (“commutation”). This causes a transient dc short circuit, cleared by control action.

Compensate

Operation of a synchronous condenser or generating set as a synchronous condenser.

Competent employee

An employee who can demonstrate to their employer at any time that they have the necessary knowledge, skills and experience to carry out the work safely and to the standard required by the employer. The asset owner may set the standard which the employer uses for assessing competence. Where qualifications are a legal pre-requisite for determining competence, such qualifications will be included in the standard.

Competent person

Person who has acquired through training, qualification or experience, or a combination of these, the knowledge and skills enabling that person to perform the task required (AS/NZS 3788).

Component

An item of equipment that can be replaced or refurbished and interfaces with the remaining equipment . For example, a spring bolt in a suspension bus assembly.

Component format (circuit diagrams)

A circuit diagram format where the terminals of each item of equipment are grouped together and connections are made to other equipment as required by the circuit function.

Compressor

Machine which produces compressed air for operation of circuit-breaker pneumatic mechanisms and for arc extinction in air blast circuit-breakers.

Condition assessment

The process of determining the state of being of an asset for the purpose of estimating its ability to provide reliable service for a defined time period. A detailed examination of a transmission line (or a specified section of a line) to: assess and record the condition of all the major components of the line (including major bridges), check Transpower’s main asset records to confirm their accuracy and to identify and correct errors, identify and document defects which will require maintenance work to ensure that the line will meet Transpower maintenance standards until the next assessment.

Condition assessment contractor

The contractor responsible for determining the physical condition of transmission line components.

Conduction

Direct transmission of energy by a medium that does not involve movement of the medium itself.

Conductive pathway

Any structure built of electrically conducting material that may carry transferred voltages to remote locations.

Conductive structure

Any structure built of electrically conducting material such as steel lattice towers, steel poles and concrete poles.

Conductive temperature

Means the temperature of the conductor assumed for the purpose of calculation. The temperature is determined by the use of IEEE 738:1993 (emissivity and absorptivity shall be taken as 0.5 unless otherwise identified), or as measured at the surface of a conductor by means of an appropriate contact thermometer, or equivalent method.

Conductor

Bare conductor or conductor not insulated to full working voltage (unless the context conveys another meaning). Conductor includes conductive parts. All copper, aluminium and steel; conductor including stranded, tubular and solid.

Conductor fitting

Any item designed to be attached directly to a conductor or earth wire. This includes helical fittings, dampers, spacers and compression fittings.

Confirmation of Offer

confirmation by telephone that a specified grid asst will be removed from or returned to service in accordance with its offer and is the trigger for giving a PTP.

Connected party

Customers supplied from the grid exit points (GXP). An entity contracting with a grid owner to connect to the grid at a point of connection.

Consequential arcback

HVDC; with one valve experiencing an arcback, the second normally conducting valve also has an arcback. It causes a two phase ac short circuit which is cleared by circuit-breaker tripping.

Conservator

A tank mounted at the highest point of a transformer oil system to allow for thermal expansion and contraction of the oil.

Conservator cell

A rubber bladder in the conservator to isolate the transformer oil from the air. Air through the breather enters the cell allowing for thermal expansion and contraction of the oil.

Conservator diaphragm

A horizontal flexible rubber division in the conservator to isolate the transformer oil from the air.

Constraint

A local limitation in the transmission capacity of the grid required to maintain grid security or power quality.

Construction contractor

A company or person(s) contracted by Transpower to install and commission new or reconditioned equipment. Note: The construction contractor may also be contracted to decommission equipment.

consultants

Individuals providing services to Transpower, but not directly employed by Transpower. These individuals would work for other companies that are contracted to provide services to Transpower. Some consultants are permanently located at Transpower locations for the duration of their contracts.

contact (circuit-breaker)

Two or more conductors designed to establish circuit continuity when they touch, and which, due to their relative motion during operation, open or close a circuit or (in the case of hinged or sliding contacts) maintain circuit continuity.

contact operator

An operator who issues a reclose block and remains available to receive communications from the RCB holder.

contingency

The uncertainty of an event occurring, and the planning to cover for this.  For example a single contingency could be: (a) In relation to transmission:  The unplanned tripping of a single item of equipment, or (b)  In relation to fall in frequency:  The loss of the largest single block of generation in service, or   loss of one HVDC pole.

contingent event

Those events for which, in the reasonable opinion of the grid operator, resources can be economically provided to maintain the security of the grid and power quality without the shedding of demand.

continuous load

A load which is energised and constant throughout the discharge duty cycle.

continuous operating voltage

The designated permissible rms voltage that may be applied continuously between the surge arrester terminals.  Often abbreviated MCOV.

continuous rating

The maximum rating to which equipment can be operated continuously.

continuous signal receive

Continuous signal receive is applied to an acceleration line protection scheme in situations where performance of the scheme would be degraded by either: (a) the protection signalling link being out of service, or (b) the protection at the far end of the line being out of service. CSR ensures that the protection trips rapidly for all faults on the protected line.  The protection will also trip rapidly for some faults at and beyond the far end bus.

continuous voltage

The maximum permissible rms value of power frequency voltage which can be applied continuously between the line and earth terminals of an arrester without exceeding the thermal rating of the arrester elements.

contract controller

A staff member of Grid Asset Management - Field responsible for managing maintenance contracts.

contract manager/supervisor

A contractor employee responsible for planning and implementing the relevant commissioning processes and procedures.

contract release

A long-term release given for specified equipment to be operated in accordance with a contract agreement.

contractor

Party contracted to provide a service to Transpower (not staff, customer, consultant, or supplier). See also maintenance contractor.

contractor (function)

The party giving a fault response including inspection of power transformers.

contractor (line maintenance)

The contractor awarded any of the Transpower line maintenance contracts.

Contractor Managed Documentation

Documents prepared, managed and maintained by the site maintenance contractor. For the requirements of this standard the CMD would cover the relevant site oil information.

contractor recall time

The estimated time required during the work for the contractor to: (a) return the equipment in a condition suitable for service, and (b) be clear of the equipment.

contractors

Individuals providing services to Transpower, but not directly employed by Transpower. These individuals would work for other companies that are contracted to provide services to Transpower. Some consultants are permanently located at Transpower locations for the duration of their contracts.

control circuit (circuit-breaker)

Lower voltage circuits of a circuit-breaker used for controlling the closing and opening operations of the main equipment.

control device

A device for control of power system equipment including automatic voltage regulators, reactive power controllers etc, but not including any function embedded in an RTU.

control equipment

Substation equipment used directly for control of primary system equipment e.g. automatic voltage regulators and temperature monitors used on power transformers.

control owner

Is a person who applies any process, policy, device, practice, or other actions which mitigate risk (ISO31000).

control room

The location at which the connecting party has facilities to receive operational instructions from the grid operator and to act on those instructions.

controlled area

A fenced area around station buildings for which entry is possible only  with a magnetic swipe card, key or through a remote-controlled gate.

controlled document

A document registered within the Transpower system.  A controlled document is enduring (i.e. is in force unless formally withdrawn) and subject to version control.  A controlled document is issued, amended and withdrawn through a formal quality process system.

Controlled Document Project Record

A progress checklist and sign-off record that is compiled for each controlled document development project.

controller

The employee who exercises operational control of some power system equipment.

controller (function)

An employee who has operational control of Transpower equipment, including the issuing of operating instructions.

convection

Transmission of energy from a hot area to a cooler area by the natural movement of a fluid or gas.

coolers

A combination of hollow panels, pipes and/or thin walled tubes designed to dissipate the heat from the transformer’s oil to an external cooling agent, air or water.

copper loss

Electrical loss accompanying the flow of current, usually in reference to the windings of a transformer or generator.

copper/copper sulphate

A reference electrode consisting of copper in a saturated copper sulphate solution.

corrosion current

The current flowing in a corrosion cell formed between the grillage and the anode.

corrosion: heavy

The galvanizing is intact at less than 95% of the surfaces of both the leg and the grillage.

corrosion: light/medium

The galvanizing is intact over the entire steel grillages and over at least 95% of the legs. Small areas of rust at the balance surfaces.

corrosion: nil/very light

The galvanizing is intact over the entire steel grillages and over at least 99% of the legs.

cost of non-supply

An assessment by the grid operator of the costs the end users would incur for the duration of an interruption of supply.

coupling capacitor

A capacitor voltage divider for use with power line carriers for injecting and receiving radio frequency signals for power line protection signalling, voice communication and data transfer on high voltage transmission lines.

COV

Continuous operating voltage.

CP

The prevention or reduction of corrosion of buried steel grillage by making it act as the cathode in a galvanic or electrolytic cell.

CPI sign (lines)

Circuit, phasing, identification sign.

crane

For the purposes of the PECPR Regulations a crane is a powered device equipped with mechanical means of raising and lowering loads suspended by means of hooks, twist locks, shackles, pins, or lifting blocks, and that, by moving the whole device or any part of it (such as a boom, jib or trolley), can reposition or move raised loads both vertically and horizontally; and includes all parts down to the hook, twist lock, spreader, lifting beam, or other part of the crane to which the load of the system supporting the load will be attached but that are an integral part of the crane.

crossarm

The horizontal arms used on transmission towers and poles to which are attached the insulator strings supporting or terminating each of the line conductors.

CSR

Continuous signal receive.

CTO

Advice by telephone of changes to offers (availability, capability or configuration) for today; after 13:00 today, for changes to offers for tomorrow where the changes alter previously advised start or end times or both. Note: changes include forced outage situation where an AFS statement cannot be given within 15 minutes, requiring a CTO (previously an offer was "in-service" by default) complete with an indicative or actual return time.

cubicle

That part of a metal-clad switchboard, incorporating primary connections, secondary wiring and control circuits, into which the circuit-breaker truck is inserted.

current control (HVDC)

(a) Joint current control In this mode, operator commands to raise or lower the pole current order are accepted only at the master station which automatically ensures that the pole current orders at the rectifier and inverter are updated correctly to ensure there is no loss of current margin.(b) Separate current control In this control mode, pole current orders at both converter stations are separately updated by the local operator at each station.

current divider

Current sharing device for MAV anodes.

current drainage tests

Tests in which current is applied for a short period, usually with temporary anodes and power sources, in order to assess the magnitude of the current needed to achieve permanent protection against electrochemical corrosion.

current limits (HVDC)

There are a large number of maximum and minimum current limits to ensure equipment ratings are not exceeded, or to increase HVDC transfer for off-normal HVDC configurations.  May be manually and/or automatically applied.

current transformer

An instrument transformer for obtaining measurements of currents at high voltages.  The current and voltage is reduced to a low level, suitable for metering and/or protection purposes.

cut-off voltage

The prescribed level at the battery terminals at which a discharge is considered finished. Discharging the battery beyond this point may result in damage to the battery.

CVT

A voltage transformer comprising a capacitor divider unit and an electromagnetic unit (transformer),so designed and interconnected that the secondary voltage of the electromagnetic unit is substantially proportional to and in phase with the primary voltage applied to the capacitor divider unit.

cyclic loading (of a transformer)

A normal loading duty which imposes a regular loading pattern on a transformer in definable cycles (usually daily and annual).  During cyclic loading a transformer may experience loads in excess of its maximum continuous rating for short periods.

cylinder

Is a pressure vessel with its height/length being several multiples of its diameter, typically used for the transport of gases. Often known as gas bottles.