Siemens Coupling contactor relay, 2 NO + 2 NC, 24 V DC Part number 3RH2122-1HB40

Product Overview

The Siemens 3RH2122-1HB40 is a coupling contactor relay in the SIRIUS 3RH2 series. It is designed with two normally-open (NO) and two normally-closed (NC) auxiliary contacts and a coil voltage of 24 V DC (operating range 0.7…1.25 × Us). The device uses screw-type terminals, fits frame size S00, and is suitable for PLC output switching and auxiliary circuit control.

Key Features

• Coupling contactor relay with 2 NO + 2 NC auxiliary contacts
• Coil/control voltage: 24 V DC, range 0.7…1.25 × Us
• Frame size S00 – compact form factor
• Screw-terminal connections for auxiliary and control circuits
• Designed for use with auxiliary and control circuits upstream of larger switches/contactors
• High mechanical durability and reliable switching behaviour under industrial conditions

Technical Specifications

• Article Number: 3RH2122-1HB40
• Series / Type: SIRIUS 3RH2 coupling contactor relay
• Contact Configuration: 2 NO + 2 NC
• Control Supply Voltage (Coil): 24 V DC (operating range 0.7…1.25 × Us)
• Rated Insulation Voltage: 690 V AC (pollution degree 3)
• Surge Voltage Resistance: 6 kV
• Mechanical Service Life (Typical): approx. 30,000,000 switching cycles
• Height × Width × Depth: approx. 57.5 mm × 45 mm × 73 mm
• Ambient Operating Temperature: -25 °C to +60 °C
• Connection Type: Screw-type terminals; conductor cross-section for auxiliary contacts: 0.5…4 mm²

Compliance & Certifications

• Designed in accordance with IEC/EN standards for auxiliary contactors/relays (e.g., IEC 60947-5-1)
• Front protection rating: IP20, finger-safe
• Rated for industrial mounting and operation up to 2,000 m altitude without derating

Applications

This coupling relay is ideal for switching auxiliary control circuits, PLC outputs, and enabling downstream power contactors in industrial automation systems. Typical uses include control panels, machine tool logic, conveyor systems, and other automation equipment where compact, reliable auxiliary switching is required.