The grounding system component of an electric power system is most often not given the attention it deserves since most of the equipment that comprise a grounding system resides underground or is obscured from scrutiny. However a ground system is as important to an electric power system as is a foundation is to a building. A poorly designed or maintained grounding system is most often the cause of unexplained events and phenomena within an electric substation or switchyard. Problems that can result from a poorly designed or maintained grounding system are:
Stressed insulation of potential transformers, bulk power transformers, grounding transformer, etc., from reflective voltage waves caused by lightning and transients
False-operation of apparatus such as disconnects opening, circuit breakers tripping, etc.
Large transfer potentials during faults to ground of the power system, resulting in equipment mis-operation or damage to electronics
Excessive ground potential rise (GPR) during faults and lightning stroke currents, resulting in high step and touch potentials, and transfer voltages
Grounding systems are generally designed to fulfill two purposes that are often mutually exclusive: Protection of workers and the public; Proper operation of equipment and systems attached to the grounding system. A common misnomer in the electric power industry is a grounding system or grid with a low ground impedance (or resistance) is free from excessive step and touch potentials. On the contrary, a grounding system with a low ground impedance (or resistance) can be unsafe for workers and the public for even small magnitude faults (i.e. high impedance faults); conversely a grounding system with a high ground impedance can be made safe for workers and the public, but offer little benefit to equipment performance.
OrionMagnetics offers turnkey design and evaluation services and solutions for the electric power, communications, energy exploration, gas, maritime, mining, and refining industries. A sample of the services we offer are
- Designs of grounding systems for any applications
- Designs of equipotential systems
- Step and Touch potential assessments
- Site/Facility audits, investigations and inspections
- Equipment performance assessments and improvements
- Comprehensive computer modeling
- Sizing of personal and temporary protective grounds
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