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3.5.5 Ground-Fault Protection
Where ground-fault protection is used, the supply shall be:
a) Grounded through a neutral-grounding device that limits ground-fault voltage to 100V or less; and
b) De-energized in less than 1s if ground-fault current exceeds 20% of the prospective ground-fault current.
3.6.2 Neutral-Grounding Devices
A neutral-grounding device shall be:
a) Continuously rated, except when ground-fault tripping is provided;
b) Monitored so as to de-energize the supply in less than 60s if the neutral-grounding device opens; and
c) Connected as close as practical to the supply neutral.
12. CATOLOGUE NUMBERS
APPENDIX A: EXCERPT FROM CAN / CSA M42100: USE OF
ELECTRICITY IN MINES
Sigma3: Ground fault relay & neutral grounding resistor monitor
GM-AM1: Analog meter, 3 ½ in. 0-1 mA with scale 0-100%
NGRS-XX: Sensing Resistor
TxA ZSCS: T2A, T3A, T6A or T9A zero sequence current sensors.
Rx-yA ZSCS: R4-17A, R7-13A or R8-26A zero sequence current sensors.
C-EG44EM SIGMA3
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