Abnormal electrical conditions may be caused by the generator or by the system, so it is critical that they be protected from both external and internal faults. This can be done with protection relays based on the size of the generator, from 12kW to 2MW+. We need to take the same approach we use for system grounding on electrical systems that are supplied by the utility with generators to mitigate this type of damage. Since the goal is to limit surge voltages and current in the windings caused by transient overvoltage, the impedance grounding of the generator neutral or X0 can both protect the windings and potentially save the generator from catastrophic damages.
Utilizing high resistance grounding (HRG) where a neutral grounding resistor (NGR) is connected from the generator transformer to ground can limit the fault current during a phase-to-ground fault. Typically, the NGR will limit the fault current to 5 or 10 A with the following benefits:
- Reduces arc flash hazards associated with phase-to-ground faults
- Eliminates damage to rotator and stator
- Prevents operation of over current devices until fault can be located
- Can be used alongside ground fault location system
- Can be used on low- or medium-voltage systems
For generators with a delta winding, Bender also offers insulation monitoring devices for ungrounded applications. It is a general promise of generator suppliers to deliver reliable and consistent power to their customers. To meet this goal, it is crucial to have a reliable and healthy system.
Bender offers services for consultants for NGR sizing and charging current calculations, to propose the right solution for ground fault and NGR monitoring. No matter what kind of grounding arrangement, Bender provides a solution.
For more information about this application or to learn more about Bender technology related to your specific application, contact our team of experts.
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