Transient Recovery Voltage and Its Effect on a Circuit Breaker

One problem that is pervasive in the power grid and not well understood is called the Transient Recovery Voltage (TRV). When a short-circuit due to a fault in high voltage or medium voltage system is switched-out by a circuit breaker, the voltage across the breaker poles rapidly increases; as high as twice the operating voltage. …

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Optical Ground Wire For Communication Between Power Substations

With the advent of modern microprocessor relaying, much of the communication between relays has been shifting from power-line-carrier apparatus or microwave to fiber. Since power utilities own the easements for the high voltage transmission lines, it is only logical to install fiber up there. One ingenious location is the lightning shield wire. It is the …

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Choosing Between Resistor and Reactor for Neutral Ground Impedance

Ground Fault Current Path

Faults involving ground produce high fault current magnitude especially when the transformer(s) neutral is solidly grounded. The neutral ground circuit in the transformer provides the return path for the fault currents. To limit this current, impedance – either in the form of a reactor or a resistor – is installed in the neutral circuit. See …

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