I-Gard offers a complete range of Neutral Grounding Resistors, from 480V to 69,000V for resistance grounding of industrial power systems.
All of our NGRs are manufactured in Canada. Designed and tested under our CSA SMTC program meaning they are approved by CSA and meet all applicable standards including CSA 295-15 and CSA 22.2 Part 1.
We have UL rated, seismic rated and OSHPD approved designs available.
The resistor must be sized to ensure that the ground fault current limit is greater than the system’s total capacitance-to-ground charging current. If not, then transient over-voltages can occur.
The charging current of a system can be calculated by summing the zero-sequence capacitance or determining capacitive reactance of all the cable and equipment connected to the system.
When it is impractical to measure the system charging current, the “Rule of Thumb” method may be used: