Use the NGR Monitor Set-Point Assistant to view recommended NGR monitor settings for your system. The recommended ground-fault trip setting assumes a tripping system. The ground-fault trip setting can be adjusted for other configurations.

Feel free to contact Littelfuse Startco with any questions or comments.

NGR Monitor Model

SE-325 Economical NGR monitor for systems up to 25 kV
SE-330 NGR monitor detecting open or shorted resistors up to 35 kV
SE-330AU Australian NER monitor meeting requirements of AS/NZS 2081.3:2002
SE-330HV High-voltage NGR monitor for 15- to 72-kV systems

System Parameters

System Voltage

Line-to-Line Volts

Line-to-Neutral Volts

Neutral-Grounding Resistor

Neutral-Earthing Resistor

Let Through Current Amps

Resistance Ohms

Location

Current Transformer
*CT-Primary should approximate NGR Let Through Current

CT Selection

CT-Primary Rating Amps

CT Selection

CT-Primary Rating

Recommendations

Sensing Resistor

Ground-Fault Trip Level

Earth-Fault Trip Level

ResTrip Level (Minimum)
*Do not set above line-to-neutral voltage

Vn Trip Level (Minimum)
*Do not set above line-to-neutral voltage

RES switch setting

S5 Configuration Switch

Version 2.4

IMPORTANT NOTE: This set-point assistant is provided for purposes of example only. Littelfuse Startco does not assume responsibility for liability for use based upon the examples shown, and is not liable for contingent or consequential damages, or for expenses sustained as a result of incorrect application, incorrect adjustment, or a malfunction. Littelfuse Startco relays have a wide variety of applications; those responsible for its application must take the necessary steps to assure that each installation meets all performance and safety requirements including any applicable laws, regulations, codes, and standards.