UPS for 208 Vac Grid, B120US Installation Guide, doc. rel. 3.0
87
9.
Switch OFF the RECTIFIER AC INPUT circuit breaker.
10.
Switch OFF the BYPASS AC INPUT circuit breaker.
11.
Switch OFF the BATTERY INPUT circuit breaker.
The switches are now positioned as shown in Table 12 below.
Table 12: Position of the CBs in maintenance bypass mode
Battery box input
(on battery box)
Rectifier ac input
(CB 2)
Bypass ac input
(CB 3)
UPS AC output
(CB 5)
Maintenance bypass
(CB 6)
OFF
OFF
OFF
OFF
ON
12.
Verify 0V across all terminals in the system.
The system is now in maintenance bypass mode and can now be safely serviced.
7.3.
Transferring the UPS back to normal mode from maintenance bypass
mode
In maintenance bypass operation, the UPS's ac circuit breakers are positioned as shown in Table
13 (see Figure 59 for CB locations).
Table 13: Maintenance bypass operating position of the circuit breakers
Battery box input
(on battery box)
Rectifier ac input
(CB 2)
Bypass ac input
(CB 3)
UPS AC output
(CB 5)
Maintenance bypass
(CB 6)
OFF
OFF
OFF
OFF
ON
To put the system in normal mode operate the UPS’s ac circuit breaker as follows:
13.
Switch ON the RECTIFIER AC INPUT circuit breaker.
14.
Switch ON the BATTERY circuit breaker.
15.
Switch ON the BYPASS AC INPUT circuit breaker.
16.
Switch ON the UPS (
Operation > system on
).
Wait for the system to automatically transfer to inverter once all the power modules are
operational.
17.
On the system controller LCD screen press
Operations > transfer load to bypass
.
18.
Verify that the bypass indicator is lit on the controller.
19.
Switch ON the AC OUTPUT circuit breaker.
20.
Switch OFF the MAINTENANCE BYPASS circuit breaker.
