Design and Development of Door Interlock for Air Circuit Breaker

Abstract

With the increasing demand of uninterrupted power supply, the responsibility of each and every component in the electrical circuit used to transmit the electrical power is also very high. Circuit Breakers are the last link in the series of apparatus protecting the electrical circuit during Faults and Short circuits. Air Circuit Breaker is a low voltage electrical switching device used for low voltage power distribution. They provide over-current and short-circuit protection for electrical circuits over 400A to 6300A. Air circuit breaker operates in air as an arc extinguishing medium under Atmospheric conditions. At present the Door interlock prevents the switchboard panel from being opened when the ACB is closed or in connected position, the panel door is only operable when the ACB is isolated from the live contacts and hence prevents the undesirable operation of the breaker and ensures the safety of the equipment and operator. But it is also possible to switch ON the ACB when the panel door is open which can lead to electric shock and severe injury to the operator. The aim of the project is to design and develop the door interlock for the air circuit breaker which will not allow the opening of switchboard panel door when the ACB is in ON or in connected condition. Also the circuit breaker should not get closed or connected when the door of the switchboard panel is open.