In modern Australian commercial and industrial installations, circuit breakers must do more than respond to overloads and short circuits. Facilities such as data centres, hospitals, workshops, and manufacturing plants require the ability to trip breakers remotely in response to emergency or control system signals.

The 24V Shunt Release for DPX³ Circuit Breakers enables this functionality within the DPX³ MCCB platform.

Designed to comply with AS/NZS 60947-2 and integrated in accordance with AS/NZS 3000, the shunt release transforms a passive protection device into an actively controlled isolation point.

Principle of Operation – Solenoid Actuation

A shunt release is a power-to-trip accessory.

Internally, it contains a solenoid coil and armature. When a 24V signal (AC or DC depending on model) is applied, the electromagnetic field drives the armature forward, mechanically striking the breaker’s trip bar.

This action:

• Unlatches the internal mechanism • Opens the main contacts • Forces the breaker into the TRIP position • Removes supply instantly

The coil is designed for impulse duty. Continuous energisation after tripping can cause overheating. For this reason, control circuits typically incorporate an auxiliary contact wired in series to disconnect the coil supply once the breaker opens.

Fire System Integration

One of the primary applications is integration with building fire systems under AS 1670.

When smoke detection occurs, the Fire Indicator Panel (FIP) sends a 24V DC signal to designated distribution boards.

The shunt release then trips the MCCB supplying:

• HVAC systems • Mechanical ventilation • Smoke control equipment • Non-essential services

Using 24V control aligns with Safety Extra Low Voltage (SELV) practices and avoids routing hazardous 240V control circuits through fire panel interfaces.

Emergency Stop (Category 0 Stop)

In industrial environments, emergency stop circuits require immediate removal of power—classified as a Category 0 stop.

A red mushroom-head emergency stop button is wired to energise the 24V shunt release coil.

When activated, it:

• Trips the upstream MCCB • Removes supply to machinery • Overrides welded contactors • Provides upstream isolation

This ensures rapid shutdown regardless of downstream equipment state.

Control Circuit Protection

The shunt release coil must be protected from short-circuit conditions.

Typical installations include:

• DIN-rail fuse holders • Miniature circuit breakers (MCBs) • Interface relays • Control transformers (if voltage conversion required)

Proper circuit protection ensures that a coil fault does not disrupt upstream power distribution.

Installation within the DPX³ Frame

The shunt release accessory fits into a dedicated compartment within the DPX³ breaker housing.

Correct installation requires:

• Secure mechanical engagement • Verification of armature alignment • Proper routing of flying leads • Identification of control wiring

Control wires must be clearly labelled to indicate that they may remain energised from external sources even when the breaker is OFF.

Integration with SCHNAP Electric Products

SCHNAP Electric Products supports remote trip installations with complementary wiring and control accessories.

Bootlace ferrules ensure secure termination of fine-stranded control wires feeding the shunt release coil.

DIN-rail fuse holders provide dedicated protection for the 24V control circuit.

Interface relays assist where signal isolation is required between fire panels and switchboard control wiring.

Spiral wrap and cable management accessories maintain segregation between control circuits and main power conductors within the enclosure.

These components contribute to a safe and organised remote tripping system.

Frame Compatibility and Voltage Matching

Shunt releases are frame-specific.

A DPX³ 160 model differs mechanically from DPX³ 250 or DPX³ 630 frames. Voltage selection must also match the site control system (24V AC or 24V DC).

Proper specification ensures:

• Mechanical compatibility • Correct impulse force • Reliable breaker actuation • Long-term operational integrity

Incorrect pairing may result in failure to trip or coil damage.

Commissioning and Testing

After installation, testing should confirm:

• Correct coil voltage supply • Successful remote trip activation • Auxiliary contact interruption of coil current • Proper breaker reset function

Periodic testing ensures the remote trip system remains functional when required during emergency conditions.

Conclusion

The 24V Shunt Release for DPX³ Circuit Breakers provides essential remote tripping capability for modern safety and control systems.

By enabling fire panel integration, emergency stop functionality, and controlled isolation within compliant switchboards, it enhances operational safety and response time.

In advanced electrical distribution systems, the ability to trip remotely is not optional—it is fundamental to risk management and life safety.