Generator Monitoring Systems

Electrical Safety for Generator Monitoring Systems

Portable and stationary generators need appropriate ground-fault monitoring systems in order to maximize reliability. As per IEEE Std 3005.4 (Recommended Practices for Improving the Reliability of Emergency and Stand By Power Systems), a properly designed impedance-grounded system can increase reliability. These systems limit damage associated with line-to-ground faults and permit continued operation in the presence of a single line-to-ground fault.

Bender offers neutral grounding solutions for simple single-source systems, up to main-tie-main applications, or more sophisticated multi-source systems. The protection provided by the NGRM series of neutral grounding resistor monitors has the unique capability to switch from active to passive mode when multiple sources are tied to the same bus. This allows one NGRM to monitor the complete parallel grounded system, saving both time and money when locating a ground fault. The NGRM series provides monitoring of the impedance grounded systems required by the Canadian Electric Code since 2018.

Whether you use bus grounding via a zig-zag transformer, or a more sophisticated paralleling switching configuration, Bender can support you. Our solution offers advanced features such as automated fault location, active and passive modes of ground-path monitoring, and ground-fault protection with a wide-frequency response. With a Bender system, you can detect harmonics and non-power-frequency currents circulating between generator neutrals that can cause damage to critical equipment such as the grounding resistor or load windings.

Generator grounding

Typically, Bender recommends one of our HRG series (1, 2, or 3) for generator applications. Historically, low resistance grounding (LRG) or hybrid grounding has been used on medium-voltage generator applications. Replacement parts and monitoring solutions for such applications are available if conversion to HRG is not feasible.


In addition to grounded generators, Bender has extensive experience applying insulation monitoring to DC field excitation of utility generators and synchronous generators. Bender’s unique insulation monitoring devices provide superior monitoring for ungrounded applications even when dealing with varying field voltage.

Global differences

North American applications for portable or mobile power generation are often solidly grounded. Bender's RCM series ground-fault relays can be used to provide ground fault protection in such applications. In other jurisdictions, mobile power generators are left ungrounded for continuity of service in applications like construction or emergency power. For applications required to meet IEC in particular, "protective isolation with insulation monitoring and shutdown," customers often use the isoGEN423. For more information on solutions for different generators, read through our downloads section below or contact us.

Monitor Ground-Path Continuity
Current based ground-fault detection relies on the return path.

Enhanced Ground-Fault Protection
Non-linear loads are better protected by a relay that has wide frequency response.

Selective Coordination
Selective Coordination

Protect Generator Windings
Resistance grounding limits the amount of damage to the generator.

Downloads

CategoryNameSizeLanguageTimestampD-/B-Number
Technical Information How to Size an NGR (US) 424.0 KB EN2019/05/13 10:31:3513.05.2019 10:31:35
Product Brochures HRG & LRG Systems (US) 5.2 MB EN2020/03/05 21:02:3305.03.2020 21:02:33
Technical Information 2020 Guidelines (US) 5.6 MB EN2020/01/28 14:33:1428.01.2020 14:33:14
Product Overviews Overview Brochure 4.2 MB EN2022/08/25 20:30:5725.08.2022 20:30:57
Technical Information NGR Checklist (US) 245.3 KB EN2022/11/07 16:39:0207.11.2022 16:39:02
Technical Information Guideline on NGR/Safety Ground Monitoring 234.7 KB EN2019/09/20 13:52:3320.09.2019 13:52:33

Products

Ground-Fault Monitoring, Ungrounded

ISOMETER® isoGEN423
ISOMETER® isoGEN423

Insulation monitoring device for unearthed AC, AC/DC and DC systems (IT systems) up to 3(N)AC, AC 400 V, DC 400 V

ISOMETER® iso685…
ISOMETER® iso685 Series

Ground-fault detector for ungrounded AC/DC systems

Resistance Grounded Systems (HRG/LRG)

LINETRAXX® NGRM500

Monitor for use in high-resistance grounded systems

LINETRAXX® NGRM700

Monitor for use in high-resistance grounded systems

Ground-Fault Monitoring for Grounded Systems

LINETRAXX® RCMA420
LINETRAXX® RCMA420

AC/DC ground-fault monitor

LINETRAXX® RCMA423

AC/DC ground-fault monitor

Ground-Fault Monitoring, Ungrounded

ISOMETER® isoGEN423
ISOMETER® isoGEN423

Insulation monitoring device for unearthed AC, AC/DC and DC systems (IT systems) up to 3(N)AC, AC 400 V, DC 400 V

Details
ISOMETER® iso685…
ISOMETER® iso685 Series

Ground-fault detector for ungrounded AC/DC systems

Details

Resistance Grounded Systems (HRG/LRG)

LINETRAXX® NGRM500

Monitor for use in high-resistance grounded systems

Details
LINETRAXX® NGRM700

Monitor for use in high-resistance grounded systems

Details

Ground-Fault Monitoring for Grounded Systems

LINETRAXX® RCMA420
LINETRAXX® RCMA420

AC/DC ground-fault monitor

Details
LINETRAXX® RCMA423

AC/DC ground-fault monitor

Details

Standards

CSA C22.2 No. 295
IEEE C57.32
IEEE 3003.1
UL 508
CSA C22.2 No. 14
NFPA 70
CSA C22.1