What it is and where it fits
This is a Siemens SIRIUS power contactor, designated 3RT1016-1MB41-0KT0, in the compact S00 frame size. It's a 24 VDC-coil unit with screw-type terminals for the main current circuit, meant for switching motor loads in control panels. The S00 frame keeps the footprint tight at 45 mm wide, 57.5 mm tall, and 72 mm deep, so it fits neatly on a 35 mm DIN rail per EN 50022, with side-by-side mounting possible at a 6 mm spacing. The IP20 rating on the front and terminals means it's finger-safe inside an enclosure, not meant for washdown — this one lives in a dry panel.
What the ratings mean for your motor load
The key number for a sourcing buyer is the AC-3 rating: 4.5 kW at 400 V. That's the motor-starting duty — switching a standard three-phase induction motor on and off under load. The S00 frame handles that current comfortably. For plugging or inching (AC-4 duty, where the contactor makes and breaks the motor at full locked-rotor current), it's rated 8.5 A at 400 V. That's a tougher service, so if your application does frequent reversing, this is the figure to watch. The coil is a DC-operated unit, pulling 1.4 W to close and 1.4 W to hold. That's a low, steady draw — no AC hum, and it plays well with 24 VDC control supplies common in PLC cabinets. Wire sizes: the screw terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²), and up to 2x (0.75 to 4 mm²) for the main contacts. AWG equivalents are 2x (20 to 16) or 2x (18 to 14), and a single 12 AWG.
Coordination and protection
For Type 2 coordination (no damage to the contactor on a short circuit), the required upstream fuse is a gL/gG 20 A. For Type 1 coordination (contactor may need replacement after a fault), it's a 35 A gL/gG. The contactor is rated for pollution degree 3, which is the standard for industrial environments with conductive dust or moisture — typical for the inside of a panel near a motor line. Operating temperature range is -25 to +60 °C, so it handles the heat inside a packed enclosure without derating down to that upper limit.