OPERATIONEaton 9155 UPS (8–15 kVA) User's Guide 164201553 Rev G (www.eaton.com/powerquality) 63Internal Bypass StartupTo start the UPS in internal Bypass mode:1. If you have an optional MBM/PDM or wall-mounted bypass switch, verify thatthe maintenance bypass switch is in the UPS position (see Figure 45 on page 68or Figure 48 on page 72).2. If an optional isolation transformer is installed, switch the input circuit breaker tothe ON position.NOTE When using the optional isolation transformer, Bypass mode is available only for 240V phase-phase(180° phase angle).3. Switch on utility power where the UPS is connected.4. Wait for the front panel LCD to illuminate.The indicator flashes.5. Remove the breaker tie from all battery circuit breakers.6. Switch all battery circuit breakers to the ON position.The indicator stops flashing.7. Press any button on the front panel display to activate the menu options.8. Using the button on the front panel display, scroll to the Control menu optionand press the button.9. Press the button to select the Go to Bypass Mode option.The and indicators illuminate, indicating the UPS is operating in Bypassmode. The load is now powered by utility power.To switch to Normal mode from internal Bypass mode:1. Press the button to select the Go To Normal Mode option.2. Press the ESC button until the Eaton logo appears.Maintenance Bypass StartupTo start the UPS in maintenance bypass (UPS-mounted operation):1. Verify that the maintenance bypass switch is in the BYPASS position (seeFigure 45 on page 68).2. Switch on utility power where the UPS is connected.The load is now powered by utility power.3. To transfer the load to the UPS, see “Using the UPS-Mounted MaintenanceBypass Switch” on page 68.