Auxiliary circuit relay in a S00 frame
The 3RH2122-1HB40 is a SIRIUS coupling relay — a compact auxiliary contactor for switching control signals, pilot lamps, PLC inputs, and interlock circuits in industrial panels. For a 24 V DC control circuit, the full 10 A is available, which covers most solenoid valve banks and indicator loads on a single contact set. Mechanical service life is 30 million operations, and the AC switching frequency reaches 10,000 cycles per hour — this relay is designed for high-duty-cycle auxiliary circuits where a general-purpose ice-cube relay would wear out in months. The arcing time of 10-15 ms sets the minimum off-time between switching events to prevent contact welding.
DIN-rail fit and panel clearance
The 45 mm width means it occupies one standard modular unit (1 MU = 18 mm is typical for terminal blocks, but SIRIUS contactors use a wider pitch — this is a 2.5-MU-wide device). These are the minimum air gaps to adjacent metalwork or other devices for heat dissipation and arc flash containment. In a dense panel, plan for these gaps or use the SIRIUS busbar system that spaces devices automatically. This matters when installing in a sloped cabinet or on a swing frame where the rail is not perfectly vertical.
Coil, contacts, and wiring
In a cabinet with many such relays, the cumulative heat load adds up; at 50 relays, that is 140 W of continuous heat that must be ventilated or the ambient temperature inside the enclosure rises above the 60 °C operating limit. Two instantaneous contacts are provided — the catalog does not specify NO/NC configuration, so the contact arrangement must be verified from the product marking or wiring diagram on the side of the device. Degree of pollution 3 means the relay is rated for conductive pollution environments — typical in industrial panels where dust, humidity, or condensation can create tracking paths. The storage temperature range of -55 to +80 °C covers unheated warehouses and shipping containers.
Sourced to order against the BOM quantity through independent distribution channels. The part is RoHS-compliant per the substance prohibition date of 10/01/2009, covering the EU RoHS directive.