Circuit breaker-type transfer switches and bypass/isolation switches
Mar 19, 2012
Circuit breaker-type transfer switches and bypass/isolation switchesMedium-Voltage (5-15kV) Circuit Breaker-Type Transfer Switches and Bypass/Isolation Switches are UL tested, listed, and labeled†under UL 1008A, making them suitable for use in legally required emergency power systems. These switches transfer electrical loads between normal and emergency power sources through the carefully controlled†opening and closing of circuit breakers and may be configured for open- or closed-transition transfer. All switch functions are controlled by a powerful and versatile RPTCS programmable microprocessor-based control system. Though designed for unattended operation, switches include controls for manual operation and provide maximum protection for personnel. All Medium-Voltage Circuit Breaker-Type Switches meet or exceed stringent IEEE, NEMA, and ANSI standards.
For either the open- or closed-transition configuration, if the primary source is lost, the control initiates an open-transition transfer to the emergency source by tripping the primary source breaker and closing the emergency source breaker. When open-transition retransfer is selected, the switch first verifies that the primary source has returned, opens the emergency source breaker, and then closes the primary source breaker.†When closed-transition retransfer is selected, the switch first performs a synch check to ensure that the primary source is in synchronism with the emergency source, then parallels the two sources by closing the primary source breaker, and finally opens the emergency source breaker.
Medium-Voltage Circuit Breaker-Type Bypass/Isolation Switches provide all the functions of an automatic transfer switch plus the ability to bypass power from live source to load in the event the transfer switch becomes disabled. In addition, they are designed to allow isolation and de-energization of the automatic transfer breakers for maintenance, testing, and repair. The operator can easily choose between load-break bypass and no-load-break bypass by means of a selector switch on the front of the control cubicle.
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