Siemens 3RS18001HQ00 Electromechanical Relay With Three Changeover Contacts

Siemens 3RS18001HQ00 is an electromechanical relay in an industry-standard enclosure with three changeover contacts (3CO) and screw terminals, designed for three‑phase monitoring and control applications. This 3RS1800‑series device provides a 24 V universal coil (AC/DC) or a 110–120 V AC coil variant, allowing flexible integration with both low‑ and high‑voltage control circuits. Rated for up to 3 A on its output contacts at up to 250 VAC (AC‑15) at 50/60 Hz, it uses three SPDT contact sets for independent switching. Typically used as a phase/voltage loss relay to detect a missing phase and trigger protective actions in industrial drives, motor controllers, and control panels.