The Siemens 3VA1580-5EF32-0KA0 is a 3-pole IEC frame 1000 circuit breaker from the 3VA1 series, rated at In=800A with a breaking capacity class M delivering Icu=55kA at 415V. The TM240 thermal-magnetic trip unit provides overload protection adjustable from Ir=560A to 800A, and fixed short-circuit protection at Ii=5 x In.
The TM240 thermal unit's adjustable Ir range (560-800A) lets you match the breaker to the actual continuous load, not just the frame size; set it to the cable or busbar ampacity, not the transformer nameplate. The shunt trip coil draws from a separate control circuit (220-250V DC or 208-277V AC), so verify your control voltage matches before wiring — a common miss on retrofit swaps.