Littelfuse.com

© 2019 Littelfuse, Inc.

Rev: 1-B-050420

1 of 6

Protection Relays & Controls

NGR SERIES – CANADA

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 – Canada systems are specifically designed

for use in Canadian applications. For applications in the US

and other parts of the world, please use the NGR series – US.

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.

Features

Enclosure

The NGR Series - Canada comes pre-installed

in a ventilated NEMA 3R galvanized steel

enclosure and components are pre-wired to

terminals for ease of installation. Back view

shown on left.

ER Series Sensing Resistor

Use with the SE-330 to continuously monitor the continuity

of a neutral-grounding resistor and eliminate hazardous

voltage levels at the relay.



ER-600VC is designed for use on systems up

to 600 V for indoor applications. Available in

optional moisture-proof enclosure (shown on

left) for outdoor applications.



ER-5KV for use on systems up to 4160 V for

indoor applications.



ER-5WP is designed for use on systems up

to 4160 V and comes with weather-protected

terminals for outdoor installations.

Earth-Fault Current Transformer

Used with the SE-330 to measure ac current flowing through

the NGR for use with the continuity monitoring circuit and to

detect ground faults.



ELCT5-31 used with SE-330 for 5 A

and 10 A NGRs.



SE-CS10-2.5 used with SE-330 for 10 A

and 15 A NGRs.



5SHT-101-E used with SE-330 for 25 A NGRs.

Benefits



Eliminate phase-to-ground arc-flash incidents



Eliminate transient overvoltages



Reduce point-of-fault damage



Can provide continuity of service during a ground fault



Includes current transformer and ER series sensing

resistor for use with Littelfuse monitoring relay and for

ease of installation.

Neutral Grounding Resistor System