Neutral Grounding Resistors

Low Resistance Grounding Resistor

Neutral grounding resistor protect power transformers and generators from damaging fault currents. Neutral Grounding Resistors limit the ground fault current to a high level (usually 50 amps or more) so protective fault clearing relays and current transformers can operate properly. These devices are then able to quickly clear the fault, usually within a few seconds. The importance of this fast response time is that it:

  • Limits damage to equipment
  • Prevents additional faults from occurring
  • Provides safety for personnel
  • Localizes the fault
  • UL Listed
  • CSA approved up to 7200v
  • Seismic Zone 4 Certifications and type tests also available

The limited fault current and fast response time also prevent over-heating and mechanical stress on conductors. Like the solidly grounded neutral system, the circuit must be shut down after the first ground fault. Low resistance grounding resistors are typically rated between 100 and 400 amps for 10 seconds, and are commonly found on systems up to 34.5kv.

Features & Capabilities:

  • Neutral Grounding Resistors (NGRs) protect power transformers and generators from damaging fault currents
  • Available for systems rated 240v to 72kv line-line (CSA approved up to 7200v)
  • Current ratings up to 5000 amps.  Designed and tested per IEEE32
  • Certified test reports and installation/maintenance instructions accompany each NGR
  • Standard enclosures are mill-galvanized.  Optional enclosure finishes available, as well as CT’s, PT’s, & disconnect switches.

Low Resistance Grounding


The Industry's Most Commonly Used Neutral Grounding Resistors

 

Line-Neutral Voltage

 

Current (Amps)

 

Part #

 

Approx Wt (lbs)

 

Approx Dims.

Ten Second Ratings

L”xW”xH”

1390

100

NG13-1-10

260

36x36x36

1390

200

NG13-2-10

260

36x36x36

1390

400

NG13-4-10

260

36x36x36

2400

100

NG24-1-10

300

36x36x36

2400

200

NG24-2-10

300

36x36x36

2400

400

NG24-4-10

300

36x36x36

2400

600

NG24-6-10

300

36x36x36

4160

100

NG41-1-10

500

48x48x48

4160

200

NG41-2-10

500

48x48x48

4160

400

NG41-4-10

500

48x48x48

4160

600

NG41-6-10

500

48x48x48

8000

100

NG80-1-10

750

48x48x48

8000

200

NG80-2-10

750

48x48x48

8000

400

NG80-4-10

750

48x48x48

8000

800

NG80-8-10

750

48x48x48

8000

1000

NG80-10-10

1500

96x48x48

Extended Time Ratings

1390

25

NG13-25E

250

36x36x36

1390

50

NG13-50E

250

36x36x36

2400

25

NG24-25E

300

36x36x36

2400

50

NG24-50E

500

48x48x48

4160

25

NG41-25E

750

48x48x48

4160

50

NG41-50E

900

48x48x56

Continuous Ratings

277

5

NG277-5C

100

29x18x17

277

10

NG277-10C

100

29x18x17

347

5

NG347-5C

100

29x18x17

347

10

NG347-10C

100

29x18x17

1390

5

NG1390-5C

250

36x36x36

1390

10

NG1390-10C

250

36x36x36

1390

25

NG1390-25C

500

48x48x48

2400

5

NG2400-5C

300

36x36x36

2400

10

NG2400-10C

500

48x48x48

2400

25

NG2400-25C

550

48x48x48

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