SF6 Circuit Breakers and Current Transformers for High Voltage Lines
Here’s a typical set-up of circuit breakers (left) in a high voltage switchyard. The circuit breaker here is a SF6 (Sodium Hexafluoride) type. SF6 is used as a medium of the circuit breaker because of its high dielectric strength (2-3 times than that of air) and approximately 100 times effective than air in quenching spurious arcing. On the right of the Circuit breakers are current transformers which transform HV line current into safe and manageable level for proper relaying and coordination. In the even of transmission line or equipment fault, the current transformers will sense the high amount of current which will then trigger the circuit breakers to open the circuit.
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