Uses a heat-sensitive spring to break the contact in an overloaded condition; automotive circuit breakers will reset when the circuit cools off.

Uses a heat-sensitive spring to break the contact in an overloaded condition; automotive circuit breakers will reset when the circuit cools off.

• A. Circuit breaker
• B. Circuit protector
• C. Coil
• D. Condenser

Answer: (A)

When a circuit is overloaded, heat builds up in a thermal protective element. A heat-sensitive spring (often part of a bimetallic strip) deflects as it heats and trips the latch, opening the electrical contacts to stop current flow. Once the circuit cools, the spring returns to its original shape and the contacts close again, resetting automatically. This automatic reset on cooling is the hallmark of a circuit breaker, distinguishing it from fuses, which must be replaced after a melt. The other options don’t describe a self-resetting overload protection: a coil is typically part of a relay or magnet, and a condenser is a capacitor. Circuit protector can be a generic term, but the specific heat-triggered, auto-reset mechanism points to a circuit breaker.

When a circuit is overloaded, heat builds up in a thermal protective element. A heat-sensitive spring (often part of a bimetallic strip) deflects as it heats and trips the latch, opening the electrical contacts to stop current flow. Once the circuit cools, the spring returns to its original shape and the contacts close again, resetting automatically. This automatic reset on cooling is the hallmark of a circuit breaker, distinguishing it from fuses, which must be replaced after a melt. The other options don’t describe a self-resetting overload protection: a coil is typically part of a relay or magnet, and a condenser is a capacitor. Circuit protector can be a generic term, but the specific heat-triggered, auto-reset mechanism points to a circuit breaker.