Description

This is the Siemens SIRIUS 3RH21 contactor relay, the AC-powered counterpart to the DC model we discussed earlier. It is a fundamental building block for control systems, designed to multiply signals and manage logic in industrial automation.

Core Specifications:

Contact Configuration: 3 NO + 1 NC (3 Normally Open and 1 Normally Closed). This versatile setup allows you to trigger three separate actions while maintaining a safety interlock or a “ready” status signal on the NC contact.

Control Supply Voltage: 24 V AC (50/60 Hz). This is a standard voltage for many industrial control transformers, making it a “plug-and-play” choice for panels that don’t use a DC power supply.

Frame Size: S00. Measuring just 45mm wide, it’s built for high-density DIN rail mounting where every millimeter of panel space counts.

Connection Type: Screw Terminals, ensuring a robust, industry-standard connection for reliable wiring.

Why Choose the AC Version?

Robust Logic: Since it operates on AC, it’s often preferred in environments where simple control transformers are used rather than switching power supplies.

High Performance: Despite its small size, it boasts high contact reliability, even for low currents (essential for PLC inputs).

Modular SIRIUS System: It shares the same footprint and accessory ecosystem as the rest of the 3RT/3RH series, meaning you can swap or add components easily.