What this coupling relay does that a standard contactor cannot
The 3RH2131-1VB40-ZW97 is a SIRIUS coupling relay — it switches auxiliary circuits, not motor loads. Its 3 instantaneous contacts handle 10 A at both 24 V and 230 V, meaning the same thermal current rating applies across the low-voltage and line-voltage range, so you don't need separate contactors for PLC-level and panel-level signals. The 24 VDC coil draws 1.6 W closing power and includes a built-in diode surge suppressor — that suppressor is polarity-sensitive, so the DC control wiring must respect the marked polarity. The pickup threshold is 0.85 of rated voltage, and dropout occurs at 1.85 times rated, giving a wide hysteresis band that prevents chatter on a sagging 24 V bus.
Panel fit and spacing for size S00
Clearance requirements: 10 mm upward, forward, and downward, plus 6 mm at the sides.
Wiring and environmental limits
Pollution degree 3 means the relay is rated for conductive dust environments typical of industrial panels without conformal coating. Minimum relative humidity is 10% — relevant for dry, heated control rooms where electrostatic discharge risk rises. The mechanical endurance is 30,000,000 cycles typical, with a maximum AC switching rate of 10,000 operations per hour and DC pulse durations of 20 to 80 ms.