Vertiv 10H92873, Installation And Operating Instructions Manual

Page: 20 / 202

10H92873 - rev. 8 - 01/2019 - pag. 16
Fig. 15 - Synchro Error 0 [°]
When there is NO SYNC we need to determine the offset between the two wave forms, in the example of "Fig.
14" there is a difference of 88,56°.
In order to ensure a correct synchronisation we will enter a value in PNU 731.32, this is our 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
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
After having calculated the new value for PNU 731.32, please proceed with following steps to change it:
• Close QS2 on this first UPS, wait for the Warning W1.1 - Bypass Switch Open - to be cleared;
• Stop the inverter;
• In PPVis click on "Service Tools" and select "Parameter";
• Set "Access level" to "Superservice": PNU 51=4;
• Set "Function Selection" to "HW-Init": PNU 52=2;
• Set PNU 731.32 "EXT_SYNCH_OFFSET" to "the new calculated value" (16121 in our example);
• Set "Function selection" back to "Return" : PNU 52=0;
• Set "Access level" back to "Normal operation" : PNU 51=1;
• Start the inverter and open QS2 again, check that the SYNC is now according to example in "Fig. 15";
• Close QS2 again;
• Procedure complete for UPS1;
NOTE 2:
This offset compensation procedure must be followed for ALL the units connected to ESB.