Wednesday, 22 May 2013

MAKE BEFORE BREAK CHANGEOVER


Under normal operation switches A and C will be closed and switch B will be open.  The inverter will be feeding the load through its static switch at a phase and frequency which is synchronized with the bypass supply.

To initiate a manual transfer the inverter is first switched off after verification that the inverter is synchronized with the bypass.  This will force the static switch to affect an immediate no-break transfer to the bypass supply (can expand on this if required).  Now the manual bypass switch B can be safely closed consequently paralleling the bypass through 2 circuits: the manual bypass switch and the bypass static switch.  All that then remains is to isolate the UPS for maintenance by opening switches A and C.

Retransfer to inverter can by carried out by effectively reversing the above procedure.

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