Glossary terms beginning with H

Control by hand, that is, not automatic.

A term used in this standard to include the filling, topping up, recovering and removal of SF6 gas for electrical equipment.

General term for the component used to attach an insulator set or earthwire set to a tower. The term includes fabricated hanger brackets, solid swivels, hanger shackles and twisted barrel tongues.

Any illness, injury, or both; and includes physical or mental harm caused by work-related stress.

A device which is designed to suppress harmonic currents and voltages from being injected into the power system.

Integral multiples of the fundamental frequency causing distortion of the sinusoidal alternating waveform.

Controls the amount of HVDC transferred if the Wellington area becomes split from the rest of the North Island system. Normally disabled, can be manually selected. Normally set to 50 Hz but can be varied to help reparalleling.

RTU located at Transpower's Haywards substation for the purpose of monitoring the South Island-to-North Island power transfer runback action of the HVDC link and reporting htis state to the FRED Master at SCH.  The RTU is located in position P170 in the main relay room.

A very fast acting control at Haywards to prevent ac system collapse after faults by reducing HVDC power transfer. Normally enabled.

An activity, arrangement, circumstance, event, occurrence, phenomenon, process, situation, or substance (whether arising or caused within or outside a place of work) that is an actual or potential cause or source of harm or significant property damage. It includes a situation where a person's behaviour may be the actual or potential cause or source of harm to the person or another person.

Any activity, arrangement, circumstance, event, occurrence, phenomenon, process, situation, or substance that is an actual or potential cause or source of adverse effect to the environment. "Effect" as defined in the Resource Management Act. Any potential or probable, harmful, temporary or permanent, past present or future, acute, or chronic, effects, or any cumulative effects which arise over time or in combination with other effects. [Resource Management Act 1991].

Any activity, arrangement, circumstance, event, occurrence, phenomenon, process, situation, or substance that is an actual or potential cause or source of harm; and hazardous has a corresponding meaning. [Health and Safety in Employment Act 1992].

A rating of the hazard of pressure equipment determined from the pressure, volume and  contents of the equipment. It is determined from AS 4343.

The area around an earthing system within a contour joining all points of earth potential equal to the maximum acceptable voltage (where the voltage exceeds the specified value for the specified time) outside which zone no special precautions need be taken to protect telecommunications plants or personnel within the area.

The clamp that connects the portable earth to the earthing horn or conductor.

A gate controlling the "head" of water behind a dam (known as an intake gate) or at the upper end of a canal (known as an inlet gate). In a hydro power station, the gate controlling the entry of water to the pipeline or penstock supplying the hydraulic turbine/s.

Also referred to as "headpond", is that part of the reservoir created by the dam which is adjacent to the dam structure, and from which the water is drawn down the penstocks.

The level of water in the headwater.

Fittings for overhead lines and guys consisting of sets of rods each of which has been formed into an open helix. Each fitting normally has the same direction of lay as the outer strands of the conductor or guy strand to which it is applied. These fittings are more often referred to by their trade names "preformed", "heliformed" or "superformed".

Where any helicopter, or personnel supported by an air craft, are positioned within 5 m of live line components, that helicopter is engaged in helicopter live line work and is required to comply with helicopter live line work standards.

A surge arrester which is non-breathing, that is, so sealed that there can be no significant interchange between its contents and the external atmosphere.

A transformer which is non-breathing, that is so sealed that there can be no significant interchange between its contents and the external atmosphere.

High frequency, 3 to 30 MHz.

Term used to define a hydrogen gas detection system indicator panel which includes the components and devices connected to the indicator panel being gas monitors, gas alarm sounders and alarm lights and alarm signalling equipment for both remote and local alarms Devices such as automatic gas isolation valves which are activated by the system are to be recognised as part of the system.

A method of live testing of high voltage insulators and bushings in situ.

Supplementary material that supports the standard, but that is confidential to Transpower. Such appendices are not released with the standard, but are available on the Intranet.

A method of live testing of high voltage insulators and bushings in situ.

The use of high pressure water with or without the addition of chemicals or abrasives to remove unwanted matter from various surfaces.

Depending on context, can be one or more of: The set of voltage levels in excess of low voltage (LV); In terms of the Electricity Regulations 1993, any voltage exceeding 1000 V ac or 1500 V dc; The highest voltage level in a transformer; In terms of general usage in Transpower, the voltage on the primary winding of a transformer; Cables rated 3.3 kV ac and up to and including 33 kV ac.

A localised defect, where the coating has insufficient thickness or a discontinuity including missed area left uncoated with paint.

Means the horizontal conductor tension in a span or series of spans within a tension section.

An area of localised heating in electrical equipment.

A rigid insulated pole usually made of fibreglass reinforced plastic (FRP) used to physically bridge the distance between energised components and earth, or to bridge between adjacent phases and to enable loads to be taken or tools to be applied.

The method of performing work on live transmission circuits using tools and equipment mounted on insulating poles. Live line workers remain at earth potential and are insulated from the conductor.

Any activity liable to produce a spark, hot metal or a naked flame. Activities designated as hot work include grinding, gas cutting, welding, drilling and any other activity which could provide an ignition source. [SM-EI].

Health & Safety in Employment (Pressure Equipment, Cranes and Passenger Ropeways) DRAFT Regulations.

The maximum amount of moisture (saturation or dew point) that can be absorbed into air varies greatly with temperature and absolute pressure. When air is at the saturation point, it is said to have humidity of 100%. The relative humidity of air at any time is the percentage of moisture contained in it as compared with the maximum amount it is capable of holding at the same temperature and pressure.

Unstable state in which a machine output, system frequency, etc. runs alternatively too fast and too slow. In synchronous machines hunting can arise from phenomena closely related to system stability or to the instability of an active feedback control system, for example a speed governor, or voltage regulator.

Depending on context, can be one or more of: The set of voltage levels in excess of low voltage (LV); In terms of the Electricity Regulations 1993, any voltage exceeding 1000 V ac or 1500 V dc; The highest voltage level in a transformer; In terms of general usage in Transpower, the voltage on the primary winding of a transformer; Cables rated 3.3 kV ac and up to and including 33 kV ac.

Cables rated 3.3 kV ac and up to and including 33 kV ac.

High voltage switchgear of a type that has its associated buswork totally enclosed in metal chambers or trunking.

High voltage alternating current.

High-Voltage Direct Current. This refers to the high-voltage direct current transmission link that connects the electricity networks of the North Island and South Island. The high-voltage direct current cable runs along the seabed of the Cook Strait and is commonly referred to as the Cook Strait cable.

An automatic control system which attempts to restart HVDC valve groups (Pole 1) or the thyristor (Pole 2) after a protection operation.

Also referred to as "headpond", is that part of the reservoir created by the dam which is adjacent to the dam structure, and from which the water is drawn down the penstocks.

The level of water in the headwater.

Term used to define a hydrogen gas detection system indicator panel which includes the components and devices connected to the indicator panel being gas monitors, gas alarm sounders and alarm lights and alarm signalling equipment for both remote and local alarms Devices such as automatic gas isolation valves which are activated by the system are to be recognised as part of the system.

A term used for the assessment of the water repellency of a non-ceramic insulator.