New Circuit Breaker Plug-In Unit Offers Improved Versatility, Availability & Safety

The unit’s base design has been adapted to match that of the NZM3, allowing all connection options provided by the main device to also be implemented in the base. For safety, the live parts in the base are automatically protected from direct contact when the circuit-breaker compartment is removed. When in the ‘On’ position or pushed in, the circuit-breaker also disconnects automatically as soon as the mounting screws are loosened.

The units are installed simply by fitting the modified NZM3 with its rear terminal bolts into the guide and tightening the mounting screws. An auxiliary cable plug-in device is also available as an option. This enables the connected shunt or undervoltage releases, auxiliary contactors and also the remote operator to be tested without having to fit the circuit-breaker into the panel. Subsequently, correct operation can be tested prior to commissioning. It is also unnecessary to change the wiring when exchanging a circuit-breaker: The auxiliary conductor plug can be removed from its base and fitted onto the new terminal cables allowing operation to be quickly restored.

The technical specifications of the NZM3 plug in unit have been set to meet the wide range of requirements in the industrial sector. The new plug-in unit on the NZM3 from 250 - 500A can be used without any derating up to an ambient temperature of 40°C. For more demanding applications, the full switching capacity of the NZM3 - up to 150kA at 415VAC - can be used. The circuit-breaker can also be fitted in many positions, either vertically or turned anticlockwise/clockwise by 90°.