The Siemens 3RH2122-1BF40-ZW97 is a Size S00 contactor relay from the SIRIUS family, built for switching auxiliary circuits in motor control centers and panel applications. The coil is rated at 110 V AC/DC with a pickup threshold of 0.8 x rated value and a dropout ceiling of 1.1 x rated value — meaning it pulls in reliably at 88 V and releases above 121 V, a standard hysteresis for noise immunity in industrial environments. Mounting is via screw or snap-on onto 35 mm DIN rail, with a footprint of 45 mm wide by 73 mm deep by 58 mm tall. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, which gives flexibility in tight enclosures. Clearance requirements are 10 mm upward, 10 mm forward, 10 mm downward, and 6 mm at the side — plan your gland plate and wireway accordingly.
Contact Ratings and Duty
The 2 NO + 2 NC instantaneous contacts are rated for switching at various DC voltage levels: 10 A at 24 V, 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, 0.5 A at 440 V, 0.26 A at 600 V. For AC loads, the contacts handle 10 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. These are the make/break capacities for the auxiliary contacts — not the main power path, but the control signals, interlocks, and status feedback loops that keep a line running. The mechanical service life is typical 30 million operating cycles, with a maximum switching frequency of 10,000 operations per hour at AC and 1,000 per hour at DC-12 duty. Arcing time is 10 to 15 ms, and the DC switching duration is 7 to 13 ms — figures that matter when timing interlock sequences in a safety circuit or coordinating with a PLC scan cycle.
Lifecycle and Compliance
RoHS compliance is confirmed with a substance prohibition date of 10/01/2009, covering the EU RoHS directive. Operating temperature range is -25 to +60 °C, storage -55 to +80 °C, with relative humidity from 10 % upward. The coil draws 4 W during both closing and holding — a consistent power draw that simplifies thermal budgeting in a densely packed panel.
Panel Integration
Screw and snap-on mounting onto 35 mm DIN rail. The 45 mm width matches the standard S00 contactor footprint, so it drops into the same rail space as a 3RT2 main contactor. Wiring terminals accept 2 x (0.5 to 1.5 mm²), 2 x (0.75 to 2.5 mm²), or 2 x 4 mm² solid or stranded conductors — no special ferrules required for standard control wiring.