Xtreme Power Conversion Corporation
E91 User’s Manual
Page 45
Uninterruptible Power Supply
3-6. Parallel Operation
1. Parallel system initial startup
Please make sure that all of the running UPSs are parallel models and have the same configuration.
1) Turn on each UPS in AC mode respectively (Refer to section 3-5(1)). Then, measure the inverter output
voltage of each phase for each UPS with a multi-meter. Calibrate the inverter output voltage by configuring
inverter voltage adjustment (Refer to SETTING VOL CALI screen) in LCD menu until the inverter output voltage
difference of each UPS is within 1V or less.
2) Turn off each UPS (Refer to section 3-5(7.)). Then, follow the wiring procedure in section 2-5.
3) Remove the cover of parallel share current cable port on the UPS, connect each UPS one by one with the
parallel cable and share current cable, and then replace the cover.
4) Turn on the parallel system in AC mode:
a) Turn on the line input breaker of each UPS. If using dual-input unit, please also turn on the external bypass
input breaker. After all UPSs enter into bypass mode, measure the output voltage between two UPSs for the
same phase to make sure the phase sequence is correct. If these two voltage differences are near to zero, that
means all connections are met. Otherwise, please check if the wirings are connected correctly.
b) Turn on the output breaker of each UPS.
c) Turn on each UPS in turns. After a while, the UPSs should enter into AC mode synchronously and then, the
parallel system is now complete.
5) Turn on the parallel system in Battery mode:
a) Turn on the battery breaker (only available in long-run model) and external output breaker of each UPS.
b) Turn on any UPS. A few seconds later, the UPS will enter into battery mode.
c) Turn on the next UPS in sequence until all the UPSs enter into Battery mode and add to the parallel system.
Now the parallel system is now complete.
If you would like to have more information regarding the parallel operation, please contact your supplier or
service center for detail parallel operation instruction.
2. Add new units into the parallel system
1) You can not add new unit into the parallel system when whole system is running. You must cut off the load
and shut down the system.
2) Make sure all of the UPS are the parallel models, and follow the wiring reference in section 2-5.
3) Install the new parallel system as per section 2-6.
