Which condition do transmission circuit breakers NOT respond to?

Transmission circuit breakers are designed to protect electrical circuits by disconnecting them when certain conditions that may lead to faults or harmful situations are detected. They monitor specific electrical parameters to maintain safe operation within the power system.

High amperage, low voltage, and unequal current are all conditions that transmission circuit breakers are programmed to respond to. A high amperage scenario could indicate a potential overload or fault condition, prompting the breaker to act to prevent damage. Low voltage scenarios might suggest a fault causing a drop in voltage that could affect the stability of the system, triggering a protective response. Unequal current conditions can indicate an imbalance in the system, which could lead to overheating or equipment damage, thus necessitating the action of the circuit breaker.

Conversely, high impedance refers to a condition where the circuit presents a very high resistance to the flow of electricity, which typically does not indicate a fault condition that would threaten system safety. In many instances, high impedance would allow current to flow without causing immediate danger to the circuit, and therefore does not prompt a response from transmission circuit breakers. Thus, high impedance is the condition that they do not respond to, making it the correct choice in this context.