Coupling relay for auxiliary circuits
The Siemens SIRIUS 3RH2122-1VB40-ZW96 is a coupling relay designed to switch auxiliary circuits in control panels. It carries 2 instantaneous NO contacts rated at 10 A at 24 V, with a 24 VDC coil that draws 1.6 W closing power. The built-in diode surge suppressor handles the inductive kick from the coil, so you don't need to add an external flyback diode across the coil terminals. This relay fits the S00 contactor frame size and mounts via screw or snap-on onto standard 35 mm DIN rail. The 45 mm width and 73 mm depth let it slot into a crowded panel without eating up extra rows. Pollution degree 3 rating means it's suited for industrial environments where conductive dust or condensation is present.
Mounting and clearances
Mounting position is flexible: the relay can be rotated ±180° on a vertical surface, and tilted forward or backward by ±22.5°. Minimum clearances to adjacent components are 10 mm upwards, forwards, and downwards, and 6 mm at the sides. These spacings keep arc flash from the 10–15 ms arcing time from tracking to neighboring gear. The screw terminals accept 2 x 0.5 to 1.5 mm² solid or stranded, 2 x 0.75 to 2.5 mm², or 2 x 4 mm². Strip length follows standard practice for the terminal type; the spring-cage variant is not offered on this order code.