Description
High-resistance grounding prevents many of the problems
that are associated with ungrounded and solidly grounded
electrical distribution and utilization systems. High-resistance
grounding can limit point-of-fault damage, eliminate transient
overvoltages, reduce the arc-flash hazards, limit voltage
exposure to personnel, and provide adequate tripping levels
for selective current-based ground-fault detection and
coordination.
The Littelfuse Neutral Grounding Resistor System is a
neutral grounding resistor (NGR), current transformer, and
sensing resistor installed in a NEMA 3R enclosure used to
high-resistance ground transformers and generators. The
NGR system is designed for use with Littelfuse Neutral
Grounding Resistor Monitors for complete system grounding
and grounding protection.
The NGR series – US systems are designed for use in US
applications and all other parts of the world, not including
Canada. For applications in Canada, please use the NGR
series – Canada.

Applications
High-resistance grounding is applied on transformers and
generators where safety and continuity of service are
important. A faulted feeder may remain in operation until it
is safe to repair the fault, where allowed by the local
electrical code.