Manually-controlled arc flash energy reduction system and method for circuit breaker trip units

摘要

A circuit protection system has a normal mode, and a maintenance mode with reduced potential arc flash energy. A downstream circuit breaker is mounted within a first enclosure comprising a first access panel. A locking mechanism locks the first access panel closed. An upstream breaker is mounted within a second enclosure comprising a second access panel. A current sensor senses current and is in communication with an electronic trip unit that controls current interruptions by the upstream breaker based on a trip setting. A user interface device is accessible when second enclosure is closed, and allows user selections of normal and maintenance modes. When maintenance mode is selected, the trip unit changes the trip setting such that potential arc flash energy is reduced. The system is configured to keep the first access panel locked closed based on normal mode being selected, and allow unlocking based on maintenance mode being selected.

主权项

1. A circuit protection system, having a normal mode, and a maintenance mode in which potential arc flash energy is reduced, comprising:
a downstream circuit breaker mounted within a first enclosure, the first enclosure comprising a first access panel that is moveable to open the first enclosure such that an interior of the first enclosure is accessible, wherein the first enclosure comprises a first key lock that locks the first access panel in a closed position; an upstream circuit breaker connected to the downstream circuit breaker along an electrical circuit protected by the circuit protection system, wherein the upstream circuit breaker is mounted within a second enclosure comprising a second access panel that is movable to open the second enclosure such that an interior of the second enclosure is accessible; a current sensor for sensing electrical current in the electrical circuit; an electronic trip unit in communication with the current sensor for controlling automatic interruptions of the electrical current by the upstream circuit breaker based on a trip setting; a user interface device comprising a primary trapped key, wherein:
the user interface device is accessible when second enclosure is closed, and allows user selections of the normal mode and the maintenance mode, andwhen the maintenance mode is selected using the user interface device, the electronic trip unit changes the trip setting such that potential arc flash energy is reduced, and the primary trapped key is released and removable from the user interface device; a transfer interlock comprising a secondary trapped key, and a second key lock that is unlocked using the primary trapped key to thereby release the secondary trapped key from the transfer interlock, and wherein the first key lock is unlocked using the secondary trapped key to thereby unlock the first access panel.