Vertiv Liebert Load Bus Sync Controller, User Manual

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Vertiv
™
| Liebert
®
Load Bus Sync
™
Controller Installation Manual | 13
Figure 10 Synchro Error 0 [°]
When there is NO SYNC we need to determine the offset between the two waveforms, in the
example
Figure 9 there is a difference of 88.56°. To ensure a correct synchronization, enter a
value in PNU 731.32 (the offset).
To calculate the offset value:
PNU 731.32 = phase-error [°] * 65536 / 360 PNU 731.32 = 88,56° x 65536 / 360 PNU 731.32 = 16121
After calculating the new value for PNU 731.32, proceed with following steps to change it.
1. Close QS2 on the first UPS.
2. Wait for the Warning W1.1 - Bypass Switch Open - to be cleared.
3. Stop the inverter.
4. In PPVis click on
Service Tools
and select Parameter.
5. Set “Access level” to “Superservice”: PNU 51=4.
6. Set “Function Selection” to “HW-Init”: PNU 52=2.
7. Set PNU 731.32 “EXT_SYNCH_OFFSET” to “the new calculated value” (16121 in our example).
8. Set “Function selection” back to “Return”: PNU 52=0.
9. Set “Access level” back to “Normal operation”: PNU 51=1.
10. Start the inverter and open QS2 again, check that the SYNC is now according to example in Figure 10 .
11. Close QS2 again.
NOTE1
If by using this formula you are not able to compensate the offset, try with the following formula:
PNU 731.32 = (360 - phase error [°]) * 65536 / 360