Toshiba T90S3S08KS6XSN Manual page 137

Transferring from Bypass to UPS:
5. Power flows from the Bypass supply, through the contactor 83MC2, to the output (Route 3). The control
relays R1 and R2, and contactor coil 83MC1 is not energized.
6. Control switch "UPS" is closed, energizing relay R1. R1 operates the Switch Gate, closing the SCR.
Power instantly flows, through the SCR, from the Bypass supply to the output (Route 2). The Inverter
supply is automatically synchronized to the Bypass supply.
7. R1 also energizes coil (C1), causing the contactor to change state, switching the output power flow from
the Bypass to the Inverter supply. (Route 1).
8. Switch contact "UPS" is opened and R1 is de-energized. This turns off the Switch Gate and opens the
SCR. Coil (C1) of magnetic contactor is also de-energized.
Open
SCR
UPS - Output
Magnetic
UPS Supply
Supply Route
Doc: G8000 G8000MM G9000 Hybrid Static Transfer Switch 03 02 2009
Closed Open
Bypass - Output
Bypass Supply
Time chart of Static Transfer Switch
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Closed
UPS - Output
UPS - Supply
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