Panel fit and power termination
The 3RT1056-6AB36 is a Size S6 SIRIUS power contactor, which means the physical envelope — 172 mm high, 120 mm wide, 170 mm deep — is the standard frame for this current class in the SIRIUS family. Mounting is by screw fixing, not DIN rail snap-on, so budget for four 9 mm holes on the backplate. Clearances to grounded parts are 10 mm upwards, downwards, and sideways, and 20 mm forward — factor those into the layout for arc flash and cooling.
Switching duty and operating limits
The contactor is rated for different switching frequencies depending on the utilization category: 800 operations per hour in AC-1 (resistive), 750 in AC-3 (squirrel-cage motor start/run), 300 in AC-2 (slip-ring motor), and 130 in AC-4 (plugging/inching). The AC-3e rating also sits at 750 ops/h. These are the maximum mechanical switching rates — the thermal load of the motor starts will set the practical limit. The operate times (both AC and DC coil) are 40 to 60 ms, so the total break time from coil de-energization to arc extinction is roughly 50 to 75 ms — relevant for coordination with upstream protection. The coil is rated for 23 to 26 V with a pickup threshold of 0.8 times rated value (about 18.4 V minimum to pull in). These are the make-and-break capacities, not continuous current — the auxiliary switch is present and rated for control circuit duty. Mechanical endurance is 10 million operations typical, which is high for a contactor this size — it reflects the SIRIUS design target for long-life applications like conveyors or pumps that cycle frequently.
If you are standardizing on SIRIUS contactors, the Size S6 frame is the one to spec for this power band.