Circuit breakers are found in nearly all modern airplanes. Not to be confused with fuses, they protect electrical equipment from overcurrent-related damage. If the current flowing through a circuit exceeds a safe amount, the circuit breaker will disrupt it. Current will stop flowing through the circuit, thereby protecting any connected electrical equipment from damage.
Not all circuit breakers work in the same way, however. While they all protect against overcurrent-related damage, some of them have extra features, such as trip-free operation. What is a trip-free circuit breaker exactly, and how does it differ from a standard circuit breaker?
The Basics of Trip-Free Circuit Breakers
Trip-free circuit breakers are designed to disrupt the flow of current automatically — even if someone is trying to manually reclose them. They can’t be forced closed if an electrical fault is present. If there’s too much current flowing through the circuit, trip-free circuit breakers will disrupt the flow of current, and they will remain in this state until the electrical fault has been fixed.
Trip-Free Circuit Breakers vs Standard Circuit Breakers
Trip-free circuit breakers are distinguished from standard circuit breakers by preventing users from manually reclosing them. Standard circuit breakers, such as the ones in most residential homes, have an ON/OFF switch. When a standard circuit breaker trips due to an electrical fault, it will automatically move to the OFF position. The homeowner or operator can then flip the circuit breaker back to the ON position to regain the function of the connected electrical equipment.
Trip-free circuit breakers have an internal mechanism that overrides manual control. They still trip by moving to the OFF position if an electrical fault is detected. However, you can’t manually turn them back to the ON position until the electrical fault has been cleared and the breaker is reset.
Why Airplanes Use Trip-Free Circuit Breakers
Trip-free circuit breakers are often used in airplanes because they present circuits with an electrical fault from being manually closed. Modern airplanes feature many electrical components. If a wire shorts or a motor seizes, the circuit may experience an electrical fault, such as overcurrent.
Circuit breakers are designed to open the circuit to stop the flow of electricity. Trip-free circuit breakers add another level of protection by ensuring that the circuit can’t be reclosed until the fault is no longer present. Hopefully, this will give you a better understanding of trip-free circuit breakers and how they differ from standard circuit breakers.
