The Siemens 3RH2140-1VB40 is a SIRIUS coupling relay designed for switching auxiliary circuits in control panels. It carries 4 instantaneous normally-open contacts rated at 10 A with a 24 VDC coil — sized for the S00 contactor frame. Mounts via screw or snap-on onto 35 mm standard mounting rail, with a 73 mm depth, 45 mm width, and 57.5 mm height. The built-in diode surge suppressor handles the coil's DC flyback, so no external freewheeling diode is needed across the coil terminals.
Ratings and what they mean for fit
The 24 VDC coil pulls 1.6 W closing power and holds in at 85 % of rated voltage (0.85 initial value,), dropping out at 1.85 times rated — so it stays latched through brownouts down to about 20.4 V and releases reliably on overvoltage. The 4 NO contacts switch 10 A at 24 V and 10 A at 230 V, but derate significantly at higher voltages: 3 A at 400 V, 0.5 A at 440 V, down to 0.26 A at 600 V. For a 690 V control circuit, expect 1 A. The arcing time of 10–15 ms is typical for DC switching — factor that into your contactor-coil or PLC-output timing if you're sequencing multiple relays.
Mounting and spacing
Mounting position is flexible: ±180° rotation on a vertical surface, plus ±22.5° tilt forward/backward. Clearance requirements are tight — 10 mm upwards, 10 mm forwards, 10 mm downwards, and only 6 mm at the side. That side clearance is the critical one: pack relays side-by-side on the DIN rail with just 6 mm air gap, but maintain the 10 mm vertical gap for heat rise from the coil and contacts. Pollution degree 3 means it's rated for industrial environments with conductive dust or occasional condensation — no conformal coating needed for most panel builds.