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 can 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 offered 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 choose to use bus grounding via a zig-zag transformer, or a more sophisticated paralleling switching configuration, Bender can support you with 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 have 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 in the presence of varying field voltage.
Global differences
North American applications for portable or mobile power generation are often solidly grounded. The RCM series ground-fault relays can be used to provide ground fault protection on these 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 60364-5-551, 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.
