In an ambient-compensated circuit breaker, what happens when ambient temperature increases?

• A. Both overload and compensating strips bend, but only the overload responds to current
• B. Only the compensating strip bends
• C. There is no effect
• D. The device fails open

Answer: (A)

Ambient compensation uses a second strip that responds to ambient temperature to offset the main strip’s bending due to heat. When the ambient temperature rises, this compensating strip bends as well, counteracting the tendency of the main strip to bend from heat. The trip action itself, however, is still driven by the overload strip, which responds to the current flowing through the circuit. So, with higher ambient temperature, both strips bend, but only the overload strip’s bending is tied to the current and reaches the trip condition. This keeps the trip point stable across different ambient temperatures.