CUTLER HAMMER WESTINGHOUSE KT3250T MAGNETIC TRIP UNIT
The trip unit includes either a fixed or an adjustable thermal element for inverse time delay on overload and an adjustable magnetic element for protection against short circuits. In open air at 40°C, a circuit breaker with the trip unit installed will carry continuously a current (Ith) equal to the ampere rating marked on the trip unit nameplate without exceeding a 50°C rise at the terminals. The National Electrical Code (USA) requirements state that enclosed overcurrent protective devices may be loaded to a maximum of 80 percent of the open air rating (Ith).