ELR W3 Series Residual Current Relay – Model Guide & Selection Tips

Residual current protection plays a critical role in modern low-voltage distribution systems. It helps prevent electrical faults, protects equipment, and reduces downtime. The ELR W3 series is a reliable and widely adopted range of residual current relays designed for distribution boards, control panels, and industrial power systems.

This article provides a clear overview of the ELR W3 series models and offers practical selection tips to help engineers choose the correct configuration.

1. Product Overview

The ELR W3 residual current relay series offers:

• Power supply options of 24V DC or 230V AC

• Compatibility with electrical systems up to 500A

• Multiple output configurations (2, 9, or 16 channels)

• Variants with alarm outputs (indicated by I)

• Suitable for industrial equipment, building infrastructure, and automation systems

When used together with matching current transformers (W or W3 types), the relay enables leakage monitoring, fault detection, tripping functions, and system alarms.

2. Model List & Functional Differences

Below is a structured breakdown of the models you provided.

🔹 Models with 24V DC Supply

🔹 Models with 230V AC Supply

Model differences mainly lie in:

• Power supply (24DC vs. 230AC)

• Number of outputs (2, 9, 16)

• Presence of alarm indicator outputs (models ending with I)

3. Application Fields

The ELR W3 series is commonly used in:

• CNC machines and industrial machinery

• Control panels and automation systems

• Elevators, pump rooms, and HVAC systems

• Data centers and IT power distribution

• Commercial and residential building distribution cabinets

• Water treatment systems and continuous-operation equipment

These relays help monitor leakage current trends and trigger timely protection, reducing the risk of damage and unplanned downtime.

4. Practical Selection Tips

1. Choose by power supply

• Use 24DC models if the control cabinet already includes a 24V DC supply.

• Choose 230AC models for AC-based control systems.

2. Check if alarm output is required

• Models with I include alarm indication outputs suitable for:

  • Audible/visual alarms

  • PLC monitoring

  • Remote supervision

• Basic models without I are suitable for simple trip functions.

3. Select output quantity based on system size

• 2 outputs → Small systems, single equipment protection

• 9 outputs → Medium control systems, multi-point coordination

• 16 outputs → Large distribution systems or multiple device integration

4. Verify current range

• All models support monitoring up to 500A, suitable for most low-voltage industrial applications.

5. Conclusion

The ELR W3 series residual current relays offer high reliability, flexible configuration, and strong compatibility with industrial power systems. By considering the supply voltage, output quantity, and alarm requirements, engineers can quickly identify the right model for their application.

For quotations, datasheets, or technical support, feel free to contact us.