Vertiv Liebert Load Bus Sync Controller, User Manual

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Vertiv
™
| Liebert
®
Load Bus Sync
™
Controller Installation Manual | 12
3.3.2 Offset Compensation Tuning
The parameter 731.32 has been designed to compensate the phase error, introduced by the UPS
control, between the frequency reference coming from the Liebert
®
Load Bus Sync
™
Controller
and the inverter output signal. To carry out this procedure an oscilloscope between reserve input
and inverter output must be used. The Liebert
®
Load Bus Sync
™
Controller must be installed and
interconnected to the UPS system. The PNU 700 must be set to 1. The PNU 731.32 calibration
must be done on each UPS in the system. Perform the following steps:
1. Connect an oscilloscope to the first UPS.
Connect “Channel 1" to “Bypass Input L1 and N” and “Channel 2" to “UPS Output L1 and N”, as shown in
Figure 8 ) Main BUS A.
Figure 8 Offset compensation
2. With NO LOAD connected, start the inverter.
3. Open the reserve input switch QS2.
4. Verify on the oscilloscope the phase error between inverter and bypass. The following figures show an
example of NO SYNC (
Figure 9 ) and SYNC ( Figure 10 ).
Figure 9 Synchro Error 88,56 [°]
Main Bus A
CH1
Oscilloscope
CH2
Fref
Liebert
®
Load Bus
Sync
™
Reserve Input
UPS An