Suppression of High-Frequency Disturbances in Low-Voltage Circuits Caused by Vacuum Circuit Breaker Operation in Medium-Voltage Indoor Substation

In a high - or medium-voltage substation, the operation of circuit breakers can induce high-frequency over voltages in low-voltage circuits known as an electromagnetic interference (EMI). The radiated and/or conducted EMI can be the cause of damage or malfunction of low- voltage electronic equipment. This paper focuses on the effects of EMI produced due to switching of medium vacuum circuit breakers (MVCB) on the functioning of numerical relays and measuring devices which are in the vicinity of 6.6 kV Vacuum circuit breaker and remedy for reduction of effects of EMI. In this paper, a unique and cost - effective solution has been suggested and implemented to bring down the EMI effects by installation of ferrite core on control cable bunch and effective galvanized iron (GI) sheet shielding between source (MVCB) and victim (numerical relay and meter).