The Siemens 3RT5045-1BB40 is a SIRIUS S3 power contactor with a 24 VDC coil, rated for motor switching up to 66 kW at 400 V and 114 kW at 690 V (at 60 °C). The S3 frame size and pollution degree 3 rating suit it for industrial control panels with moderate to heavy electrical environments.
The 66 kW at 400 V and 114 kW at 690 V figures (both at 60 °C) tell you the motor load this contactor can handle in AC-3 duty — the standard for squirrel-cage induction motors. The 24 VDC coil draws 6 A at rated voltage, so confirm your control transformer or DC supply can deliver that inrush without sagging. Mechanical life is rated at 10 000 000 operations typical, with AC-3 switching frequency up to 1 000 cycles per hour — that's continuous duty for high-cycling conveyors or pump stations.
Snap-on mounting onto 35 mm or 75 mm DIN rail — no tools needed for the rail, but the screw terminals for main contacts accept 2x (2.5 to 16 mm²) solid or stranded, or 2x (10 to 1/0 AWG). The auxiliary contact block is field-addable (product extension auxiliary switch is supported).
Compliance and Coordination
Substance prohibitance (RoHS) compliance date is 03/01/2017, so the part meets EU RoHS and REACH requirements for current builds. For short-circuit coordination, the required backup fuse is gL/gG 160 A — size your branch protection accordingly. Insulation voltage is rated at 1 000 V, giving headroom for 690 V systems.