The Siemens 3RT2637-1AP03 is a SIRIUS capacitor contactor in size S2, designed for switching capacitive loads — typically power-factor correction banks in industrial distribution panels. Its 230 V AC 50 Hz coil (screw-type terminals) pulls in and drops out with a 10–18 ms response, and the contactor is rated for switching frequencies up to 100 operations per hour at 230 V. The 65 mm wide, 114 mm high, 130 mm deep body mounts via screw or snap-on onto 35 mm DIN rail per EN 50022.
Switching Capacity and Duty
The main contacts handle 6 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 0 A at 690 V — the zero at 690 V confirms this is a capacitor-switching contactor, not a general-purpose motor contactor. The auxiliary contact (1 N/O instantaneous) is rated at 60 V / 2 A, 110 V / 1 A, 125 V / 0.9 A, and 220 V / 0.3 A. Maximum switching frequency drops from 100 ops/h at 230–400 V (–) to 25 ops/h at 690 V, reflecting the increased stress at higher voltages.
Main power terminals accept solid conductors: 2x (0.5–1.5 mm²), 2x (0.75–2.5 mm²), or 2x 4 mm². Stranded terminations: 2x (10–35 mm²) or 1x (10–50 mm²). At 40 °C, a single 50 mm² conductor is allowed; at 60 °C, two 35 mm² conductors. The coil terminals are screw-type.