Siemens 3RQ2000-1BW00 Coupling Relay

Industrial coupling relay of Siemens SIRIUS series, equipped with 2 changeover contacts, wide voltage range 24-240V AC/DC and screw terminals. It serves as a replacement for 3TX7002-1CB00 and 3RS1800-1BW00, and is designed for PLC signal isolation and control circuit coupling.

1. Model Code Interpretation

Full Name: Enclosed industrial coupling relay, 2 changeover contacts, 24-240V AC/DC wide voltage, screw terminal connection.

2. Core Technical Parameters

3. Cross-brand & Obsolete Model Replacement List

Selection Tips: Verify full consistency of contact quantity, terminal type, mounting dimensions and electrical parameters before replacement.

4. Full Model List of 3RQ2000 Series

5. Common Faults & Troubleshooting

6. Application Scope & Industry Cases

6.1 Applicable Scenarios

PLC Signal Isolation: Couple signals between PLC outputs and field actuators to protect PLC modules.

Control Circuit Expansion: Increase available control signals to drive multiple loads via one signal.

Voltage Conversion: Connect control circuits with different voltage levels, e.g. 24V DC PLC output for 220V AC contactors.

Interference Suppression: Isolate signals in high-interference environments such as inverters and welding equipment to avoid false triggering.

Industrial Automation Systems: Production line control, packaging machinery, machine tools, conveyor systems, etc.

6.2 Non-recommended Scenarios

High-frequency switching: Not suitable for frequent switching over 10 cycles per second.

Inductive load without protection: Surge suppressors are mandatory when driving inductive loads such as motors and solenoid valves.

Corrosive environments: No special anti-corrosion treatment; not for strong acid, alkali or high salt mist conditions.

Explosive hazardous areas: Non-explosion-proof design; prohibited for flammable and explosive locations.

6.3 Typical Application Cases

Case 1: Automotive Component Production Line

Application: PLC controls clamps and welding torches of robotic welding stations.

Configuration: 3RQ2000-1BW00 isolates PLC output signals from 220V AC solenoid coils.

Result: Resists welding current interference; failure rate reduced by 90%, maintenance cost cut by 50%.

Case 2: Food & Beverage Filling Line

Application: Connect HMI touch panel and filling valve control circuits.

Configuration: Two units of 3RQ2000-1BW00 control 4 filling valves (2 NO + 2 NC) via one HMI signal.

Result: Simplified wiring, improved system reliability and fewer spare part types.

Case 3: Intelligent Warehousing System

Application: Isolate position sensor signals of stacker cranes and PLC inputs.

Configuration: 3RQ2000-1BW00 converts 24V DC sensor signals to PLC-compatible signals.

Result: Eliminates interference from long-distance signal transmission; positioning accuracy improved to ±1mm.

7. Selection Guidelines & Quick Reference Rules
8. Contact quantity by letter: A = 1CO, B = 2CO, C = 3CO
9. Terminal type by digit: 1 = Screw terminal, 2 = Spring terminal
10. Contact material by suffix: W = Standard contact, CW01 = Gold-plated contact
11. Universal voltage: Full series supports 24-240V AC/DC
12. Priority for replacement: Directly replace 3TX7 / 3RS18 series with corresponding 3RQ2000 models

Ordering Notice: Standard package: 1 unit per box; Minimum order quantity: 1 unit. It is recommended to prepare 2~3 units as spare parts for general industrial automation control.

Common Faults and Troubleshooting of Siemens 3RQ2000-1BW00 Coupling Relay

1. Relay Fails to Operate Completely
2. No power supply to coil

Measure input voltage to confirm it is within 24~240V AC/DC. Check circuit breakers, fuses and continuity of upstream control circuits, and tighten loose terminals.

2. Loose / poor terminal connection

Retighten screw terminals. Check wire crimping, broken wires and wires trapped under terminal screws.

3. Burned coil

Long-term overvoltage or frequent voltage surges will burn the coil. Replace the relay if burnt marks or abnormal odour are observed.

4. Mechanical jamming

Accumulated dust and continuous vibration cause internal armature sticking. Tap the housing gently for test; replace the relay if the issue persists.

2. Coil Pulls In but Contacts Open / Poor Contact
3. Oxidation and dust accumulation on contacts

Commonly seen in humid and dusty environments, especially for low-power signal circuits. Clean contacts after power cut and test with repeated switching operations.

2. Contact welding

Excessive load current or frequent inrush load leads to stuck contacts. Disconnect the load for verification. Replace the relay as welded contacts cannot be repaired.

3. Fault on load side circuit

Troubleshoot downstream contactors, solenoid valves and broken wires. Confirm relay fault only after excluding external failures.

3. Random Operation / Unexpected On & Off
4. Electromagnetic interference

Easily affected when installed close to inverters, motors, high-power contactors or long control cables. Route control cables away from power cables and apply shielded wires and surge absorbers.

2. Voltage fluctuation & electrical noise

Sudden voltage drop and voltage spikes cause false operation. Install voltage stabilizers and filters on the upstream side.

3. Abnormal ambient temperature

Operation above +60°C or condensation under low temperature leads to internal circuit malfunction. Improve ventilation, dehumidification and heat dissipation.

4. Abnormal Indicator Light
5. Light off, relay works normally

Only the LED bulb is damaged. The relay can remain in service or be replaced.

2. Light always on / flickering, relay does not operate

Malfunction of internal voltage divider and indicator circuit, usually accompanied by coil failure. Replace the relay directly.

5. Overheated Wiring Terminals
6. Loose wiring: Retighten terminals to specified torque.
7. Undersized wire gauge: Replace with cables with cross-section matching the load current.
8. Continuous overload: Actual load exceeds rated 5A contact current. Apply load sharing or use higher-capacity relay.
9. Frequent Failures under Inductive Load (Solenoid / Contactor)

Symptoms: Shortened contact service life, frequent contact welding and unexpected tripping

Troubleshooting: The absence of surge suppressors causes reverse high voltage from inductive loads to damage contacts during power-off. Connect freewheeling diodes (for DC) or RC snubbers (for AC) in parallel across inductive loads.

7. On-site Quick Troubleshooting Procedure
8. Cut off power → Inspect appearance, wiring and terminal tightness
9. Switch on power → Measure input control voltage
10. Observe indicator light and listen to pull-in sound to judge coil status
11. Cut off power → Test NO/NC contacts with multimeter continuity mode
12. Distinguish faults among upstream control circuit, relay itself and downstream load circuit