Residual-current device Polot CDC425J 3-phase 25A 30mA AC

Polot CDC425J 3-phase 25A 30mA AC residual-current device is designed to detect imbalance between live conductors and trip the circuit when AC-type leakage current exceeds the set sensitivity. Intended for installation in three-phase distribution boards, this device provides personnel protection against electric shock and reduces risk of fire caused by earth leakage in commercial and residential electrical installations.

Advantages

The RCD features AC-type residual-current detection with a rated current of 25 A and a trip sensitivity of 30 mA, offering a balance between continuity of supply and safety. Its three-phase design enables protection of all line conductors in a three-phase circuit with a single device. The compact form factor allows installation in standard DIN-rail consumer units and distribution boards while maintaining straightforward mechanical and electrical connections.

Suitable for

• Three-phase commercial and light industrial distribution boards where personnel protection and leakage detection are required
• Residential buildings with three-phase supplies that require AC-type RCD protection
• Protection of circuits powering motors, heating elements, and general-purpose three-phase loads

When it may not be suitable

This AC-type residual-current device is designed to detect sinusoidal alternating leakage currents; it may not operate correctly for pulsating DC or certain mixed-frequency leakage currents. Applications requiring sensitivity to DC components or specific types of residual currents (for example, fault currents containing DC offset) may need a different RCD type.

Key specifications

• Number of poles: 3-pole device for three-phase circuits
• Rated operating current: 25 A
• Residual current sensitivity: 30 mA (AC-type)
• Tripping characteristic: AC-type residual-current detection
• Mounting: DIN-rail compatible enclosure for standard distribution boards

How to use

Install the device into the distribution board on a standard DIN rail and connect the three phase conductors and neutral according to the wiring diagram and local electrical codes. Verify that supply is isolated before making connections. After installation, switch the device ON and use the test button (if present) to confirm correct tripping operation during commissioning and regular maintenance intervals. Follow applicable installation standards and, if necessary, consult a qualified electrician for correct coordination with upstream and downstream protective devices.

What to consider before purchase

• Ensure 25 A rated current is suitable for the circuit load and coordination with upstream protection
• Confirm AC-type RCD is appropriate for the installation and the type of residual currents expected
• Check available space in the distribution board for a 3-pole DIN-rail device
• Verify compatibility with local electrical codes and required certification or marking

Usage recommendations

Test the device after installation and at recommended intervals using the built-in test function to ensure continued operation. For circuits with electronic equipment or devices that may produce smooth DC leakage, consider consulting a specialist to determine if a different residual-current type is required.