Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.


See impedance
matrix which contains the impedance of each element in an electric power system.
common symbol for load impedance.
common symbol for source impedance.
zero-sequence reactance
the reactive component of the zero sequence impedance.
See symmetrical component
zig-zag ground
(1) a grounding arrangement which is used to supply single phase grounded circuits from an ungrounded three-phase delta connected electric power line.

(2) the winding arrangement within a grounding transformer.
zinc oxide arrester
a lightning arrester that consists of a stack of ZnO disks stacked within a vented porcelain tube. See gapless arrester.
zone of protection
the area of a power system for which a particular set of protective relays has primary protection responsibility. In typical cases, operation of any of these relays will open circuit breakers which will isolate this zone. Each major power system component (line, transformer, bus, generator) has a separate zone of protection.