Operation
To switch to Normal mode from maintenance bypass:
1.If an optional isolation transformer is installed, switch the input circuit breaker to the ON position.
NOTE The isolation transformer output is always 240V (180° phase angle). Any equipment connected to the output requiring 208V (120° phase angle) is at risk for damage.
2.Turn the Maintenance Bypass switch to the SERVICE position.
The UPS starts up in Bypass mode, with the load still powered by utility power.
3.Remove the breaker tie from all battery circuit breakers.
4.Switch all battery circuit breakers to the ON position.
NOTE Wait until the 
indicator illuminates before proceeding to Step 5; otherwise, power to the load may be lost.
5.Turn the Maintenance Bypass switch to the UPS position to return to Normal mode. The UPS is now powering the load.
Internal Bypass Startup
To start up the UPS in Bypass mode without an MBM/PDM:
1.If an optional isolation transformer is installed, switch the input circuit breaker to the ON position.
NOTE When using the optional isolation transformer, Bypass mode is available only for 240V
2.Switch on utility power where the UPS is connected.
3.Wait for the front panel LCD to illuminate. The 
indicator flashes.
4.Remove the breaker tie from all battery circuit breakers.
Powerware® 9155 UPS | 71 |