The LV839304 is a MasterPact MTZ3 drawout circuit breaker rated for 5000 A continuous at 40 °C, 3-pole, with L breaking capacity code. The integral instant protection is set at 153...187 kA, which is the magnetic trip threshold for bolted faults; that range tells you the breaker clears fast on hard shorts without waiting for the trip unit. Maximum breaking time is 9 ms, and the closing response is 70 ms — both matter for arc-flash energy coordination studies.
Duty cycle and mechanical endurance
Electrical durability is rated at 1000 cycles under ANSI C37.50, mechanical durability at 5000 cycles. For a 5000 A frame, 1000 electrical operations is typical for the main breaker role — you are not cycling this daily like a motor-starter contactor. The 5000 mechanical cycles cover racking and test positions over the breaker's service life.