Masterpact® NW Circuit Breakers are designed to protect electrical systems from damage caused by short circuits. These CSA / UL® Listed circuit breakers are for use on ungrounded systems rated 500 Vdc nominal (600 Vdc maximum) or less. IEC Rated circuit breakers are for use on ungrounded, grounded middle point, or grounded negative systems rated up to 900 Vdc maximum.

Features

Configurations: Drawout or Fixed Mount, 3-Pole or 4-Pole
Ratings:
- UL489 Supplement SC (3-pole only)
- NEMA AB1
- CSA C22.2 No. 5-02
- IEC 60947-2
100% Rated Circuit Breaker: Masterpact circuit breakers are designed for continuous operation at 100% of their current rating.
True Two-Step Stored Energy Mechanism: Masterpact circuit breakers are operated via a stored energy mechanism which can be manually or motor charged. The closing time is less than five cycles.
Field-Installable Accessories: Most accessories are field installable with only the aid of a screwdriver and without adjusting the circuit breaker. The uniform design of the circuit breaker line allows most accessories to be common for the whole line.
Reinforced Insulation: Two insulation barriers separate the circuit breaker front from the current path.
Isolation Function by Positive Indication of Contact Status: The mechanical indicator is truly representative of the status of all the main contacts.
Segregated Compartment: Once the accessory cover has been removed to provide access to the accessory compartment, the main contacts remain fully isolated. Furthermore, interphase partitioning allows full insulation between each pole even if the accessory cover has been removed.
Front Connection of Secondary Circuits: All accessory terminals (ring terminals are available as an option) are located on a connecting block which is accessible from the front in the connected, test and disconnected positions. This is particularly useful for field inspection and modification.
Reduced Maintenance: Under normal operating conditions, the circuit breaker does not require maintenance. However, if maintenance or inspection is necessary, the arc chambers are easily removed so you may visually inspect the contacts and wear indicator groove. The operation counter can also indicate when inspections and possible maintenance should be done.

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