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.
To reduce complexity and wiring Bender recommends using and NGRM on each resistor. Use the digital input to switch the device from auto mode to passive monitoring mode -always leaving one unit in auto mode to actively monitor the resistance to earth. As generators are added and removed the resistance reading on one primary NGR monitor (typically on the main bus) will fluctuate since the resistance is changing.
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.
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.
| Name | Category | Size | Language | Timestamp | D-/B-Number |
|---|---|---|---|---|---|
| How to Size an NGR (US) | Technical Information | 424.0 KB | EN | 2019/05/1313.05.2019 | |
| HRG & LRG Systems (US) | Product Brochures | 3.6 MB | EN | 2024/01/0303.01.2024 | |
| 2020 Guidelines (US) | Technical Information | 1.9 MB | EN | 2020/06/1515.06.2020 | |
| Overview Brochure | Product Overviews | 10.3 MB | EN | 2023/10/0202.10.2023 | |
| NGR Checklist (US) | Technical Information | 245.3 KB | EN | 2022/11/0707.11.2022 | |
| Guideline on NGR/Safety Ground Monitoring | Technical Information | 234.7 KB | EN | 2019/09/2020.09.2019 |
Products
Insulation monitoring device for unearthed AC, AC/DC and DC systems (IT systems) up to 3(N)AC, AC 400 V, DC 400 V
Ground-fault detector for ungrounded AC/DC systems
Monitor for use in high-resistance grounded systems
Monitor for use in high-resistance grounded systems
AC/DC ground-fault monitor
AC/DC ground-fault monitor
Insulation monitoring device for unearthed AC, AC/DC and DC systems (IT systems) up to 3(N)AC, AC 400 V, DC 400 V
Ground-fault detector for ungrounded AC/DC systems
Monitor for use in high-resistance grounded systems
Monitor for use in high-resistance grounded systems
AC/DC ground-fault monitor
AC/DC ground-fault monitor
National Electrical Code
Canadian Electrical Code
