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.
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
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.