Transferring To Maintenance-Bypass Mode; Transferring From Maintenance-Bypass To Normal Mode - Vertiv Liebert EXS Installer/User Manual

4.5 Transferring to Maintenance-bypass Mode

The transfer procedure puts the UPS in maintenance-bypass mode for safe servicing by a Vertiv service
technician.
To transfer from normal operation to maintenance-bypass mode:
1. Press and hold the power button for 2 seconds.
• If the bypass power is within normal operating range, the option to go to bypass displays.
a. Select Turn off local INV.
b. Press Enter to confirm the action.
c. Press Enter again.
• If the bypass power is outside normal operating range, the only option is to turn-off the
UPS .
2. Pull down on the slide latch on the front-left panel of the unit to gain access to the
Maintenance Bypass Breaker (MBB), refer to on page 41, and Figure 4.1 on page 41.
3. Set this panel aside or lay it gently on top the UPS to avoid scratching the panel or top of the
UPS.
4. Loosen the thumb screw on the mechanical interlock on the MBB.
5. Slide the interlock up and tighten the thumb screw to secure the interlock in place.
6. Close the MBB.
7. Electrically isolate the UPS module from AC-power Input by moving to the rear of the UPS and
opening the Rectifier Input Breaker (RIB), Bypass Isolation Breaker (BIB), and Maintenance
Isolation Breaker (MIB).

4.6 Transferring from Maintenance-bypass to Normal Mode

To transfer from maintenance bypass to normal operations:
1. Ensure that the mechanical interlock is still secured in the unlocked position.
2. On the rear of the UPS, close the rectifier input breaker (RIB), bypass input breaker (BIB), and
maintenance isolation breaker (MIB), see Figure 4.1 on page 41.
The UPS performs start-up checks and begins operating in internal bypass mode.
3. Verify that the UPS is operating in internal bypass mode before proceeding.
• If the unit is not in Bypass mode, see
on page 44, for the steps.
NOTICE
Risk of improper operation. Failure to have the UPS operating on internal bypass and
performing the next step will result in loss of all output power to the connected equipment.
4. On the front of the UPS, open the maintenance bypass breaker (MBB)
5. Loosen the thumb screw on the mechanical interlock on the MBB
6. Slide the interlock down and tighten the thumb screw to secure the interlock in place
7. Press and hold the "POWER" button for 2 seconds.
46
Transferring from Normal (Inverter) to Bypass Mode
Vertiv | Liebert® EXS™ Installer/User Guide