Improved Electrical Safety Through High Resistance Grounding

Abstract

High resistance grounding (HRG) is a well proven technology for improving electric reliability for many industrial and utility facilities such as used in petro-chemical, automotive, and generating plants. Many such facilities require the increased reliability for production and operational reasons. This paper will discuss the improved personnel safety aspects of using high resistance grounding on low voltage systems. In particular, the paper will discuss:•The probability of the three common faults occurring within an industrial plant: Three phase, phase-tophase, and ground faults. •How the probability of a ground fault can be used to improve electrical safety with HRG. •The impact of a ground fault on a system and the speed at which the ground fault on a solidly grounded system may propagate into a multi-phase fault •The risk reduction of a ground fault on an HRG system propagating into a multi-phase fault •The potential reduction in serious and fatal arc blast injuries through the use of an HRG system. • Potential single pole breaker clearing issues when a second ground fault occurs on a second phase This paper will include comments from recent testing which were conducted at the KEMA labs and presented in a recent IAS-Petrochemical Industry Committee Paper in September 2014. [1]

Overview of grounding schemes for solid‐state transformers in distribution networks

“…For LVAC, on top of the above grounding choices, a possible grounding design is discussed in [80,81], where high resistance is inserted between the transformer's neutral and the earth to cope with TOV. A trade-off should be made in the design of the resistance though to suppress flash hazard and guarantee timely tripping of the relay protections [82].…”

Faulted feeder identification in active grounded networks

“…For example, in conditions where the consumer loads are sensitive and power supply outage could result in production failures or economic losses, the service continuity becomes more significant and the high impedance grounding system is preferred. Many industrial and facilities employ HRG systems to improve electric reliability [6].…”