What the key ratings mean for fit
The 3RT1025-1AH04: Three NO main contacts, zero NC. The AC-4 rating of 15.5 A at 400 V governs plugging and inching duty — the high-stress switching that wears contacts fastest. For standard motor starting (AC-2), it carries 7.5 kW at 400 V. At 690 V it handles 11 kW, so it suits 400 V and 690 V distribution without a frame size jump. The AC-12 operating current of 10 A covers resistive loads like heater banks.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per EN 50022. The S0 footprint is 45 mm wide, 85 mm tall, 140 mm deep — a standard slot in most European-style panels. Side-by-side mounting is permitted, so multiple contactors pack tightly on the rail without derating gaps. Pollution degree 3 means it is rated for industrial environments with conductive dust or occasional condensation.
Termination and wiring
Screw-type terminals on the main circuit. Accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²) solid. For stranded: 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), or max 2x 10 mm². AWG equivalents: 2x (16 to 12), 2x (14 to 10), or 1x 8. The front face is IP20 — protected against finger contact; the terminal area itself is IP00, so live parts are exposed when the panel door is open. Standard panel-builder practice: keep the gland plate clearance for the 140 mm depth.
Coordination and protection
For Type 2 coordination (no damage to the contactor after a short circuit), the required upstream fuse is gL/gG 25 A. For Type 1 coordination (contactor may need replacement but no hazard), the fuse can be 63 A. This matters when the panel designer has already locked in a fuse size — the 25 A limit for Type 2 is the tighter constraint.
Environmental range
Operates from -25 to +60 °C, which covers most indoor industrial enclosures without forced cooling. Maximum installation altitude is 2 000 m — above that, derate for air density. The coil holds at 24 V rated value drawing 10 A (inrush), dropping to lower hold values. At 60 V the rated current is 2 A; at 110 V it is 1 A; at 220 V it is 0.3 A. Mechanical life is typical 10 million operations.