High-Voltage Cable Selection (IEC 183)

Glossary

Glossary

Term	Definition
Amendment 1	The 1990 update to the IEC 183 (1984) standard, which notably replaced Table I concerning voltage relationships.
Category A	A system category where earth faults are cleared as rapidly as possible, but in any case within 1 minute.
Category B	A system category where, under fault conditions, the system is operated for a short time (generally not exceeding 1 hour) with one phase earthed.
Category C	A system category comprising all systems which do not fall into Category A or B.
IEC	International Electrotechnical Commission, the organization that prepares and publishes international standards for electrical and electronic technologies.
IEC 183	The IEC standard titled “Guide to the selection of high-voltage cables,” first published as a second edition in 1984.
IEC Technical Committee No. 20	The committee within the IEC responsible for preparing standards related to “Electric cables.”
Lightning overvoltage	A phase-to-earth or a phase-to-phase overvoltage at a given location in a system due to a lightning discharge or other cause, for which the wave-shape is regarded as a standard impulse for insulation coordination purposes.
Nominal voltage of system	The r.m.s. phase-to-phase voltage by which a system is designated and to which certain operating characteristics of the system are related.
Sub-Committee 20A	The sub-committee of IEC Technical Committee No. 20 specifically responsible for “High-voltage cables.”
Terminations	The components used at the ends of a cable to connect it to other equipment. Their design is dependent on voltages, pollution, and altitude.
U	The rated r.m.s. power-frequency voltage between any two conductors for which cables and accessories are designed.
Um	The maximum r.m.s. power-frequency voltage between any two conductors for which cables and accessories are designed. It represents the highest voltage that can be sustained under normal operating conditions at any time and at any point in the system.
Uo	The rated r.m.s. power-frequency voltage between each conductor and screen or sheath for which cables and accessories are designed.
Up	The peak value of the lightning impulse withstand voltage between each conductor and screen or sheath for which cables and accessories are designed.