NGR Series - Neutral Grounding Resistor System

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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.



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.

Access specifications, certifications, check availability and order parts below

Catalog #CT secondary current AmpsInput
Voltage (V)
Mounting MethodWeight (lbs/g)built in CTsFrequencyInput Current Range (A)Input Impedance (Ohms)NEMA RatingResponse Time (ms)Sense Resistance (Ohms)StockCompare
NGR10360.05480Floor Mount0 KgNo60555.43RContinuousER-600VCCheck
NGR10380.05600Floor Mount0 KgNo60569.43RContinuousER-600VCCheck
NGR10410.05480Floor Mount0 KgNo6021383R; Weather Protected Sensing ResistorContinuousER-600VCCheck
NGR10450.05600Floor Mount0 KgNo60569.43R; Weather Protected Sensing ResistorContinuousER-600VCCheck
NGR10500.05480Floor MountNo6021383RContinuousER-600VCCheck
NGR10510.05480Floor Mount0 KgNo60555.43R; Weather Protected Sensing ResistorContinuousER-600VCCheck
NGR10520.05600Floor MountNo602173.53RContinuousER-600VCCheck
NGR10530.05600Floor MountNo602173.53R; Weather Protected Sensing ResistorContinuousER-600VCCheck
NGR10660.054160Floor MountNo605480.93R10 sER-5KVCheck
NGR10670.054160Floor MountNo605480.93R; Weather Protected Sensing Resistor10 sER-5WPCheck
NGR10680.054160Floor MountNo605480.93RContinuousER-5KVCheck
NGR10690.054160Floor MountNo605480.93R; Weather Protected Sensing ResistorContinuousER-5WPCheck
NGR10700.054160Floor MountNo6010240.53R10 sER-5KVCheck
NGR10710.054160Floor MountNo6010240.53R; Weather Protected Sensing Resistor10 sER-5WPCheck
NGR10720.054160Floor MountNo6010240.53RContinuousER-5KVCheck
NGR10730.054160Floor Mount0 KgNo6010240.53R; Weather Protected Sensing ResistorContinuousER-5WPCheck
NGR10740.054160Floor Mount0 KgNo6015160.33R10 sER-5KVCheck
NGR10750.054160Floor MountNo6015160.33R; Weather Protected Sensing Resistor10 sER-5WPCheck
NGR10760.054160Floor MountNo6015160.33RContinuousER-5KVCheck
NGR10770.054160Floor MountNo6015160.33R; Weather Protected Sensing ResistorContinuousER-5WPCheck
NGR107814160Floor MountNo602596.23R10 sER-5KVCheck
NGR107914160Floor MountNo602596.23R; Weather Protected Sensing Resistor10 sER-5WPCheck
NGR108014160Floor MountNo602596.23RContinuousER-5KVCheck
NGR108114160Floor MountNo602596.23R; Weather Protected Sensing ResistorContinuousER-5WPCheck

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