What device provides a delayed trip due to overcurrent?

• A. Fuses
• B. Circuit Breaker
• C. Relay
• D. Thermal Overload

Answer: (D)

Overcurrent protection that relies on heat buildup provides a time delay before tripping. When current stays above the rated value, heat accumulates in a sensing element (often a bimetal strip). After enough heat is generated, the strip deflects and the switch opens, producing a delayed trip. This design protects equipment from prolonged overheating while allowing short overloads to pass.

Fuses, in contrast, are fast-acting: their element melts quickly under overcurrent, causing an immediate interruption. Circuit breakers can trip instantly or after a delay depending on type, but the deliberate time delay characteristic described here is most associated with thermal overload protection. A relay is a control device and doesn’t provide the protection delay by itself.

So, the device that provides a delayed trip due to overcurrent is thermal overload protection.