The Siemens 3RT1045-1AL20-ZX95 is a SIRIUS power contactor in the S3 frame size, rated for 45 kW at 500 V in AC-3 duty — that's the motor-switching current class, so it handles a 45 kW induction motor on a 500 V line. Screw-type terminals on the main circuit, and it snaps onto 35 mm or 75 mm standard DIN rail. Side-by-side mounting is allowed, which keeps panel width tight when you're stacking multiple contactors for a multi-motor group.
Mounting and wiring
Fastens with screws or snaps onto 35 mm and 75 mm standard mounting rail — that's the standard DIN-rail footprint, so it drops into any IEC panel without adapters. The main circuit uses screw-type terminals; solid wire accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), and up to 2x (0.75 to 4 mm²). Stranded connections go up to 2x (10 to 50 mm²). Pollution degree 3 means it's rated for industrial environments with conductive dust or occasional condensation — no derating needed in a typical control cabinet.
Duty ratings and mechanical life
AC-3 maximum switching frequency is 1,000 operations per hour — that's the motor-starting duty cycle, so it handles frequent starts on a conveyor or pump without overheating the coil or contacts. AC-4 (plugging/reversing) maxes at 300 ops/h. Typical mechanical life is 10 million operations, which is standard for the SIRIUS S3 frame. Operating temperature range is -25 to +60 °C; storage from -55 to +80 °C. The front face carries IP20 protection with the cover or box terminal installed; the terminal body itself is IP00, so keep live parts inside the enclosure.
Dimensions and mounting clearances
Height 146 mm, width 70 mm, depth 139 mm — that's the envelope for the S3 frame. Side-by-side mounting is permitted, so you can gang them without a mandatory air gap between units. The 139 mm depth includes the arc chamber and terminals; verify clearance to the enclosure door if you're using a deep cover or terminal shrouds.