The 3RB1257-0KM30: The 125...500 A range covers large motor loads — think 200-400 HP at 480 V. The adjustable trip class (5...30) lets you match the relay to the motor's starting profile: class 5 for short acceleration times on pumps and fans, class 30 for high-inertia loads like centrifuges or crushers. The monostable overload warning output gives a clean signal to a PLC or annunciator before the relay trips.
Deployment Context
Designed for continuous mounting (direct to contactor) or individual mounting on a panel. The busbar connection suits high-current switchboards and motor control centers (MCCs) where bolted bus links are standard. The auxiliary screw terminals accept typical control wiring for remote reset and alarm circuits. The AC 220-240 V control supply is common across European and many Asian industrial installations.