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Description / Abstract:
This standard covers drawout-type, indoor, medium-voltage ground
and test (GT) devices for use in drawout metal-clad switchgear
rated 4.76 kV through 38 kV as described in IEEE Std C37.20.2™.1
Four GT device types are generally supplied for temporary
circuit maintenance procedures for insertion in place of the
circuit breaker as follows:
a) Simple manual devices
b) Complex manual devices
c) Simple electrical devices
d) Complex electrical devices
There may be more complicated GT devices that may include
current and/or voltage transformers, glow tubes, or other accessory
components. These more complex devices are not covered by this
standard. Due to their complexity, additional testing and
interlocking are required, and manufacturers should be consulted
for the availability and ratings of these types of devices.
Purpose
Although GT devices have been used as accessory devices in
metal-clad switchgear for decades, they were not addressed in the
standards until IEEE Std C37.20.6™-1997 was approved. This is
because they are specialized accessory devices, designed and tested
in accordance with applicable sections of circuit breaker
standards, and based on user-unique operational requirements. This
revised standard complements IEEE Std C37.20.2 and addresses the
more common GT device types. This standard also clarifies that
GT devices are not required to have the interrupting and
continuous current ratings of the circuit breakers they may
temporarily replace for the purpose of grounding and testing
medium-voltage circuits. It also recognizes that some devices may
be offered with interrupting capabilities, and required tests for
such devices are specified.