Load Transfer Procedures - Liebert 1000kVA Operation & Maintenance Manual

3.4.3

Load Transfer Procedures

Use the Monitor/Mimic Display at the SCC to determine the operating condition of the UPS system.
Press the Alarm Reset pad to clear the Alarm Messages. If all UPS modules are on-line, the only
message remaining should be Load On Bypass. Refer to Table 9 for an explanation of any other
remaining alarm messages. Call Liebert Global Services if you cannot clear any remaining alarm
messages.
If the only alarm message displayed is Load On Bypass (or no alarms), you can perform a manual
transfer of the load between the UPS system and the UPS bypass line. Changing the load from the
UPS system to the UPS bypass is called a transfer. Changing the load from UPS bypass to the UPS
system is called a retransfer. Note that the UPS system control logic can initiate automatic load
transfers and retransfers. Refer to 3.5 - Automatic Operations.
Press the Select pad to display the Master Menu on the LCD of the SCC. Move the highlighted cursor
to Load Transfer Procedures (using the Up and Down pads). Press the Select pad to display the
Load Transfer Procedures screen.
Step 1. Verify that the OK TO TRANSFER message is highlighted. If not (if the TRANSFER PRO-
HIBIT message is highlighted instead), slowly rotate the Voltage Adjust knob (Figure 10, item 6)
to match the UPS system voltage to the bypass voltage.
NOTE
1. UPS output voltage changes VERY slowly in response to movements of the Voltage Adjust
knob. To avoid overshooting, allow at least a minute for UPS output voltage to stabilize
before proceeding to the next step.
2. If the TRANSFER PROHIBIT message remains, refer to Table 9 for corrective action for
any alarm messages. Call Liebert Global Services if you cannot solve the problem.
Figure 66 Load transfer procedures screen
UPS
BYPASS
OK TO TRANSFER
TRANSFER PROHIBIT
Step 2. Perform Step 2 on the Load Transfer Procedures Screen.
a. If the load is on internal bypass, simultaneously press the UPS and Control Enable
pads (Figure 10). This will close the motorized UPS Output circuit breaker and open the
motorized System Bypass circuit breaker (SBB) in a make-before-break sequence.
b. If the load is on the UPS system, simultaneously press the Bypass and Control Enable
pads (Figure 10). This will close the motorized System Bypass circuit breaker (SBB) and
open the motorized UPS Output circuit breaker in a make-before-break sequence.
Return to the Monitor/Mimic Display screen to monitor the operation of the UPS system. Press the
Alarm Reset pad to clear any latched alarm messages removed by the new load status. Refer to
Table 9 if an alarm message other than Load On Bypass is still displayed. Contact Liebert Global
Services if you require assistance.
SELECT : MASTER MENU
VOLTAGE COMPARISON
A-B B-C C-A
-
380 380 380
-
381 380 379
TRANSFER INSTRUCTIONS
ON BYPASS
ON UPS
Adjust the UPS voltage until it equals the
1. Adjust the UPS voltage until it equals the
bypass voltage with the VOLTAGE ADJUST pot.
bypass voltage with the VOLTAGE ADJUST pot.
2. If the OK TO TRANSFER message is highlighted, If the OK TO TRANSFER message is highlighted,
simultaneously press the UPS and CONTROL ENABLE
simultaneously press the BYPASS and CONTROL ENABLE
buttons.
buttons.
Verify that the transfer was successful by checking the
3. Verify that the transfer was successful by checking the
breaker status on the "MONITOR/MIMIC" screen.
breaker status on the "MONITOR/MIMIC" screen.
Press the ALARM RESET button to clear alarms which
4. Press the ALARM RESET button to clear alarms which
are no longer active.
are no longer active
SYNCHRONIZATION
FREQUENCY
-30
50.0 Hz
50.0 Hz
MANUAL
UPS LEAD
91
Operation
0 +30
= 2 Deg