Siemens SIRIUS 3RQ2 Universal Coupling Relays

Siemens SIRIUS 3RQ2 Universal Coupling Relays Suppliers,Exporters in India

ARP IMPEX is a supplier and exporter of Siemens SIRIUS 3RQ2 Universal Coupling Relays in India. We handle requirements for PLC control panels, industrial automation systems, machine control, signal isolation, voltage conversion and replacement of older Siemens 3RS18 coupling relays.

The Siemens 3RQ2 is installed between a controller and field equipment when the controller output cannot be connected directly to the load. It receives the control signal and switches it through one or more isolated changeover contacts.

A typical application is converting a 24 V DC PLC signal into a contact that controls a 110 V or 230 V AC circuit. The relay can also protect sensitive controller inputs and outputs from electrical interference, voltage peaks and faults occurring on the field side.

One major advantage of the 3RQ2 is its wide-range control supply. The same relay version can operate from 24 to 240 V AC/DC, reducing the need to keep separate coupling relays for different control voltages. Siemens supplies versions with one, two or three changeover contacts.

The range also includes a model with three hard gold-plated changeover contacts for low-current PLC and electronic control signals. Gold-plated contacts provide more dependable switching where the current is too low to clean an ordinary silver contact during operation.

For Siemens SIRIUS 3RQ2 price and availability, share the complete Siemens part number, required quantity and destination country.

What the Siemens 3RQ2 Does

A standard PLC output has limits on voltage, current and the type of load it can switch. Connecting a contactor coil, solenoid valve or another control load directly may exceed the controller output rating or expose it to electrical interference.

The 3RQ2 creates an isolated switching stage between the controller and the field circuit. It can be used for:

• Galvanic isolation between PLC and field equipment
• Signal amplification
• Multiplication of a control signal through several contacts
• Conversion between different control voltages
• Switching contactor and relay coils
• Protecting controller outputs from voltage peaks
• Reducing the effect of electromagnetic interference
• Providing voltage-free contacts to another system

The relay can work as an input coupling relay or an output coupling relay. The actual wiring depends on whether the signal is entering the PLC or being sent from the PLC to an actuator.

Siemens 3RQ2 Product Variants

3RQ2 with One Changeover Contact

This version suits straightforward signal isolation or voltage conversion where only one switching contact is required.

Typical uses include:

• Switching one contactor coil
• Providing one isolated PLC output
• Converting a 24 V signal into a voltage-free contact
• Interfacing one field signal with a controller
• Replacing an applicable Siemens 3RS1800 relay

3RQ2 with Two Changeover Contacts

The two-contact version can operate two circuits from the same control input.

One contact may switch the field load while the second provides feedback, indication or an additional isolated signal to another controller.

3RQ2 with Three Changeover Contacts

The three-contact version is used where one input signal must be reproduced across several circuits.

It may operate a contactor, provide an alarm indication and send status information to another control system at the same time.

3RQ2 with Hard Gold-Plated Contacts

Siemens provides a three-changeover-contact version with hard gold-plated contacts. This version is intended mainly for low-current electronic and PLC signals where reliable switching in the milliampere range is important.

The complete Siemens article number also identifies whether the device uses removable screw terminals or spring-type push-in terminals.

Technical Specifications

• Brand: Siemens
• Product range: SIRIUS
• Series: 3RQ2
• Product type: Universal electromechanical coupling relay
• Main article-number family: 3RQ2000
• Main purpose: Signal isolation, amplification and voltage conversion
• Control supply: 24–240 V AC/DC
• Rated AC frequency: 50/60 Hz
• Contact options: One, two or three changeover contacts
• Low-current version: Three hard gold-plated changeover contacts
• Connection systems: Removable screw or spring-type push-in terminals
• Maximum conductor cross-section: Up to 4 mm² on applicable terminals
• Mounting depth: Approximately 90 mm
• Housing: Industrial control-panel enclosure
• Mounting: Standard DIN rail
• Terminal identification: Labelled terminal covers
• Service identification: DataMatrix code
• Typical coordination: Siemens SIMATIC controllers and SIRIUS contactors
• Approvals: CE, UL/CSA and EAC on applicable products
• Railway suitability: Available on applicable versions

These are family-level details. The contact rating, terminal type, operating characteristics and approvals must be confirmed from the complete Siemens part number.

Features

• Wide-range 24–240 V AC/DC control supply
• Reduces the number of voltage-specific relay variants required
• Available with one, two or three changeover contacts
• Hard gold-plated contact option for low-current PLC signals
• Provides galvanic isolation between control and field circuits
• Converts PLC signals to different control-voltage levels
• Amplifies signals where a controller output cannot switch the load directly
• Protects PLC interfaces from field-side voltage peaks
• Helps reduce electromagnetic interference reaching the controller
• Removable terminals allow the panel wiring to remain in place
• Screw and push-in terminal options are available
• Individual terminal blocks can be replaced without rewiring the complete device
• Large terminal capacity supports practical control-panel wiring
• Compact 90 mm mounting depth suits industrial enclosures
• Suitable for SIMATIC controllers and SIRIUS contactors
• One wide-voltage model simplifies spare-parts stock
• International approvals suit machinery and export projects
• Applicable versions support railway control applications
• Suitable for new panels and Siemens 3RS18 replacement requirements

Why the Wide-Range Supply Is Useful

Older coupling-relay ranges often required separate models for 24 V DC, 110 V AC, 230 V AC and other control voltages.

The Siemens 3RQ2 covers 24 to 240 V AC/DC through one wide-range input. This allows panel builders and maintenance teams to use fewer relay variants across different projects.

For an industrial plant, this can simplify spare inventory. Instead of keeping several voltage-specific relays, one correctly selected 3RQ2 contact version can cover several control-supply requirements.

The wide-range input does not mean that every output load is automatically suitable. The connected voltage, load current, utilisation category and switching frequency must remain within the relay contact rating.

Applications

Siemens SIRIUS 3RQ2 Universal Coupling Relays are used for:

• PLC input and output isolation
• SIMATIC controller interface circuits
• PLC output signal amplification
• Voltage conversion in control panels
• Contactor-coil switching
• Solenoid-valve control
• Interposing relay applications
• Motor control panels
• Machine automation panels
• Process-control systems
• Packaging machinery
• Material-handling systems
• Conveyor control panels
• Pump and compressor control
• HVAC control panels
• Industrial ovens and furnaces
• Building automation systems
• Water and wastewater plants
• Railway control equipment
• Infrastructure automation
• Alarm and indication circuits
• Remote control and signalling
• Panel retrofit projects

Replacement of Siemens 3RS18 coupling relays

The 3RQ2 is particularly useful where a low-power PLC signal must control a higher-voltage circuit or where the controller needs electrical separation from the connected field equipment.

Use as a PLC Interface Relay

In a typical output application, the PLC energises the 3RQ2 coil. The relay contact then switches the contactor, valve, alarm or another control load.

This keeps the field load away from the PLC output circuit. If the load produces a voltage spike or develops a fault, the coupling relay provides an additional level of separation between the controller and the field wiring.

The hard gold-plated version is more appropriate where the relay contacts switch low-current electronic signals instead of contactor coils or other standard control loads.

Siemens 3RQ2 and 3RQ1 Difference

The 3RQ1 and 3RQ2 are both coupling relays, but they are intended for different control circuits.

• Siemens 3RQ1: Uses force-guided contacts for monitored and safety-related circuits
• Siemens 3RQ2: Universal industrial coupling relay for normal PLC and automation signals

The 3RQ2 is commonly used for galvanic isolation, voltage conversion and signal amplification. It should not replace a force-guided 3RQ1 in a safety circuit only because the coil voltage and number of contacts appear similar.

Where SIL or Performance Level certification is required, the complete safety circuit and selected relay must meet the approved design.

Siemens d3RQ2 and 3RQ4 Difference

The 3RQ2 uses a robust industrial housing and provides up to three changeover contacts with a universal 24–240 V AC/DC supply.

The newer SIRIUS 3RQ4 range is based on a narrow coupling-relay design and includes fixed relay, replaceable plug-in relay and semiconductor-output versions.

The 3RQ2 may remain the preferred choice where the project requires:

• A wide-range 24–240 V AC/DC input
• Two or three changeover contacts
• Removable industrial terminal blocks
• Replacement of an existing 3RS18 or 3RQ2 relay
• Hard gold-plated contacts for several low-current signals

The correct model should be selected from the actual coil supply, output-contact arrangement and switched load.

Siemens 3RS18 Replacement with 3RQ2

The Siemens SIRIUS 3RQ2 range replaced the older 3RS18 universal coupling-relay series. Siemens retained the same basic terminal assignment for applicable replacements while reducing the number of voltage-specific models through the wide-range supply.

The replacement should still be checked for:

• Existing 3RS18 article number
• Control supply voltage
• Number of changeover contacts
• Contact material
• Switched load and current
• Screw or spring-type terminal requirement
• Available control-panel space
• Required approvals

A three-contact standard relay should not automatically replace a hard gold-plated version used for low-current electronic signals.

Selecting the Correct Siemens 3RQ2 Relay

A request for “Siemens 3RQ2 Coupling Relay” does not identify the complete product.

For an accurate quotation, share:

• Complete Siemens article number
• Required quantity
• Destination country
• Number of changeover contacts
• Standard or hard gold-plated contacts
• Screw or push-in terminal requirement
• Details of the load being switched

For replacement enquiries, also send a clear photograph of the existing relay label and terminal arrangement.

If the part number is unavailable, confirm whether the relay will switch a contactor coil, solenoid valve, PLC input, electronic signal or another control load.

Siemens SIRIUS 3RQ2 Coupling Relay Supplier and Exporter in India

ARP IMPEX supplies Siemens SIRIUS 3RQ2 Universal Coupling Relays for panel builders, machine manufacturers, system integrators, industrial plants, railway contractors, maintenance companies and export buyers.

We handle enquiries for Siemens 3RQ2000 coupling relays, PLC interface relays, 24–240 V AC/DC universal relays, relays with one to three changeover contacts, hard gold-plated coupling relays and Siemens 3RS18 replacement requirements.

The Siemens 3RQ2 price depends on the complete part number, number of contacts, contact material, terminal type, switched load and ordered quantity.

Send the complete Siemens part number, required quantity and destination country for price, availability and export quotation.