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Energy monitoring MCCBs offer motor protection options

01 September, 2008

Schneider Electric has announced a new generation of MCCBs (moulded-case circuit breakers) which, it says, allow both energy consumption and power to be monitored at the device for the first time. The Compact NSX breakers can accommodate special electronic control modules with built-in current sensors, including motor protection devices.

The new breakers, which cover ratings from 100-630A in four frame sizes, offer a 100kA breaking capacity at 415V. They will succeed the Compact NS range, of which more than 20 million have been sold since their launch in 1994. They will continue to be available until 2011. The two ranges are physically interchangeable.

The new range is covered by 23 patent applications covering various technologies used in the breakers. For example, there is a "ready" LED that flashes when the tripping device is ready to provide protection, and circuitry that tests the breaker continuously without interrupting its operation.

Schneider NSX MCCB

The MCCBs can display measurement data either locally on a built-in LCD, or remotely on a switchboard front panel (as shown above).

Users can choose between thermal magnetic or electronic tripping modules. For motor applications, protection is provided against short circuits, as well as against phase imbalance or loss. Additional protection can be provided for motor starting and braking, with the motor running, jogging or reversing. Another optional module provides an indication of motor overloads and contactor actuation.

The electronic protection modules incorporate three LEDs that indicate operational status and faults. Information on the number of operations, contact wear, temperatures and loads, is available via optional LCD readouts.

Pricing of the Compact NSX MCCBs will be similar to that of the earlier Compact NS versions when the cost of the previously separate current transformers and metering, which are incorporated into the new models, is taken into account.

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