Siemens SIRIUS 3RT1275-6AP36

Overview

Siemens SIRIUS 3RT1275-6AP36 is a 3-pole vacuum contactor from the SIRIUS 3RT12 series, rated 200kW @400V AC‑3, coil voltage 220–240V AC/DC. Siemens SIRIUS 3RT1275-6AP36 uses vacuum interrupter technology to suppress electric arc, suitable for heavy-duty and frequent switching of large asynchronous motors. Siemens SIRIUS 3RT1275-6AP36 is widely stocked as spare for MCC, compressor, fan and pump control cabinet overhaul.

Features

Siemens SIRIUS 3RT1275-6AP36 adopts vacuum arc extinction structure, low arc energy, long electrical service life and low contact erosion compared with air contactors. It is equipped with 2NO + 2NC auxiliary contacts for status feedback to PLC, protection relays and SCADA SOE logging. Siemens SIRIUS 3RT1275-6AP36 supports conventional coil drive, busbar connection for main circuit and screw terminals for control and auxiliary wiring. It has strong short-circuit withstand capability and is suitable for AC‑3 motor starting duty and AC‑4 frequent plugging/reversing applications. The contactor integrates built-in coil supervision and can be matched with thermal overload relays or electronic motor protection units for complete motor protection scheme. It meets IEC 60947 standards, IP20 protection for cabinet mounting.

Specs

Siemens SIRIUS 3RT1275-6AP36 AC‑3 rated 400A, 200kW at 400V, 3-pole. Coil control voltage 220–240V AC/DC 50/60Hz. Auxiliary contacts: 2NO + 2NC. Main circuit connection: busbar type; control circuit: screw terminal. AC‑1 continuous current 610A at 40°C ambient. Size S12, vacuum contactor construction. Siemens SIRIUS 3RT1275-6AP36 is widely supplied as exchange spare for heavy motor control circuit replacement.

Principle

Siemens SIRIUS 3RT1275-6AP36 closes the main vacuum contacts when the coil is energized and conducts three-phase power to the motor. When de-energized, spring force separates the contacts inside the sealed vacuum bottle; the vacuum environment quickly extinguishes the switching arc. The auxiliary contacts of Siemens SIRIUS 3RT1275-6AP36 change state synchronously with main contact action and transmit running/ready status to the control system. During frequent starting and braking cycles, vacuum interrupters reduce arc damage and extend service life. If coil open/short fault occurs, the contactor cannot pull in and sends fault signals to the interlock and alarm logic.

Applications

Siemens SIRIUS 3RT1275-6AP36 is used for large pumps, fans, compressors, mill motors, extruders and heavy conveyor drives in power plants, water treatment, chemical and marine LV MCC systems. It is selected for spare inventory and cabinet upgrade projects where high reliability and frequent switching duty are required. Vacuum contactor design makes it ideal for high-current motor loads that demand low maintenance and high switching endurance.