Thermal trip unit (L)
The thermal trip unit consists of a temperature-dependent bimetal that heats up as a result of the flow of current. This means the trip unit is current-dependent. The temperature rise in the bimetal strip depends not only on the current magnitude, but also on the ambient temperature of the molded case circuit breaker. All current values specified for thermal-magnetic trip units of 3VA circuit breakers refer to an ambient temperature of +50 ℃.