The Siemens 3RT1025-1AP04-ZW95 is a SIRIUS power contactor in size S0, with three normally open main contacts and a 24 VDC coil. It uses screw-type terminals for both the main and auxiliary circuits, and the front face carries an IP20 rating while the terminal area is IP00. The contactor is rated for a mechanical life of 10 million operations typical, and its operating temperature range is -25 to +60 °C.
What the ratings mean for your panel
The 24 VDC coil draws 10 A at rated value, so the control transformer or power supply feeding it needs to handle that inrush. The main contacts are rated for AC-2 duty at 400 V delivering 7.5 kW, and AC-4 at 400 V switching 15.5 A — the AC-4 figure governs reversing or plugging applications where the contactor makes and breaks motor current under load. For resistive loads (AC-12), the maximum operational current is 10 A. Pollution degree 3 means the contactor is suited for industrial environments with conductive pollution, typical for control panels without climate control. The screw terminals accept solid conductors from 0.5 to 1.5 mm² (two per clamp) and stranded up to 2.5 mm² (two per clamp), with a maximum of two 4 mm² solid wires. For the main circuit, stranded wire up to 6 mm² (two per clamp) or a single 10 mm² is allowed. AWG equivalents are 16–12 for solid, 14–10 for stranded, and a single 8 AWG. The auxiliary contacts accept 20–16 AWG solid or 18–14 AWG stranded, with a single 12 AWG maximum. This covers most panel wiring up to moderate motor loads.
Mounting and integration
Fastening is by screw or snap-on mounting onto a 35 mm standard mounting rail per DIN EN 50022. The contactor footprint is 45 mm wide, 85 mm tall, and 140 mm deep, and side-by-side mounting is permitted — no derating gap required between units when installed in a row. The size S0 frame keeps the panel density high.