The Siemens 3RT1025-1AC20-ZW97 is a SIRIUS S0 power contactor — the workhorse for switching motor loads in control panels up to 7.5 kW under AC-2 duty at 400 V. The 24 V 50/60 Hz coil means it integrates with standard control transformers without a DC supply.
Ratings that matter for motor switching
For reversing or inching duty (AC-4), it's rated 15.5 A at 400 V — that's the number to check if your cycle includes plugging or frequent reversals. The AC-12 maximum operating current of 10 A covers resistive and solid-state loads in the control circuit.
Coil and auxiliary contact specs
Coil is 24 V rated value at both 50 Hz and 60 Hz, with an operating range of 0.8 to 1.1 times rated voltage at 50 Hz and 0.85 to 1.1 at 60 Hz — so it holds in during sags down to about 19.2 VAC at 50 Hz. The auxiliary contacts switch up to 10 A at 24 V, 6 A at 230 V, and 0.3 A at 220 V DC, covering pilot duty and PLC inputs.
Mounting, wiring, and environment
Screw terminals accept 2x (0.5 to 1.5 mm²) solid, 2x (0.75 to 2.5 mm²) solid, and up to 2x 4 mm² max solid for the auxiliary circuits; main contacts take 2x (1 to 2.5 mm²) stranded and up to 2x 10 mm² max. Pollution degree 3 and IP20 on the front (IP00 at the terminals) mean it's suited for industrial enclosures, not open washdown areas.
Mechanical endurance is 10 million cycles typical.