New circuit breaker plug-in unit aids maintenance and improves safety
30 June 2013
Eaton has introduced a plug-in unit for its NZM3 circuit-breaker, which allows customers to exchange the circuit-breaker in a panel simply and quickly.
Servicing is also safer and more straightforward because specific system sections can be disconnected easily.
The unit’s base design has been adapted to match that of the NZM3, allowing all connection options provided by the main device to 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 under-voltage releases, auxiliary contactors and also the remote operator to be tested without having to fit the circuit-breaker into the panel. Correct operation can subsequently 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 to the new terminal cables allowing operation to be quickly restored.
The new plug-in unit on the NZM3 from 250 - 500A can be used without any de-rating 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 be fitted in various orientations, either vertically or turned anticlockwise/clockwise by 90°.
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