Bypass Switches For Critical Load Applications

Posted on June 26, 2008

Cummins Power Generation has developed a new range of closed-transition bypass switches for critical locations such as hospitals, data centers and 24/7 call centers. Cummins' BTPC bypass switches, rated from 150 to 4000 amps, are designed to offer redundant power transfer capability for situations where even a brief power interruption can have serious consequences. The closed-transition BTPC switch automatically transfers loads between two live sources (utility and backup) without interruption, the company said.

The BTPC consists of a rail-mounted, removable automatic transfer switch (ATS) and a fixed, manually operated bypass switch. Before the ATS is pulled out for repair or maintenance, the load power is diverted to the bypass switch. By having the bypass switch activated before the ATS is disconnected, the power supply continues without interruption. After the bypass switch is engaged, the ATS can be placed in one of three positions: connected (normal), test (powered but offline) and isolated (disconnected).

If utility power falters while the ATS switch is offline or disconnected, the bypass switch activates the backup generator and allows manual transfer between utility and backup power. BTPC switches from Cummins Power Generation are UL listed and safety features include closed-door ATS isolation to protect against arc flash, and shutters to protect the stationary bypass terminals during removal.

BTPC switches use field-configurable Cummins PowerCommand microprocessor-based controllers that incorporate push button controls for activating testing, programming timing delays and setting the exercise clock. Flash memory retains settings, even if the switch loses power. LED indicators provide at-a-glance system status and a digital display provides status information on other ATS equipment in the facility.