LEGRAND NUMERIC HP i 33 40 kVA Series User Manual page 80

Step 4 Start each UPS. Ensure that all UPS stay in bypass power supply mode, and with no abnormal, switch
on the external distribution switch, switch off the UPS output switch, and start the inverter of each
UPS manually, all UPS turns to inverter power supply.
Step 5 Measure the output voltage and frequency of each UPS. After each UPS turns to inverter power supply
(user can check whether the system stay in inverter power supply mode through system running
status), check whether the UPS three-phase output voltage and frequency is normal by the real-time
data in touch screen, measure the front-end three-phase output voltage of output breaker of UPS,
ensure that the inverter output voltage is normal (the three-phase output voltage = output voltage
setting ±2.0 V), and ensure that the inverter frequency is normal (the three-phase output frequency =
output frequency setting ±0.1 Hz). Record the measured three-phase voltage effective value of each
UPS.
Step 6 Switch off the output breaker of one UPS and measure the voltage difference at the front and rear of
the output breaker in any other UPS, ensure that the corresponding phase voltage effective value
difference less than 5 V, and then parallel the UPS. If it does not meet the requirement, the UPS with
big voltage deviation cannot be put into parallel system and it is necessary to debug again.
Step 7 Shut down the inverter of the UPS. Ensure that there is no abnormal alarm in any of the UPS, shut
down each UPS manually. All UPS turn to bypass power supply.
Step 8 Check the bypass phase sequence.Close the output breaker of UPS 1 (ensure that the total breaker of
load is disconnected, or once the output breaker of UPS 1 is closed, it will supply power for load),
maintain the output breaker of other UPS' is disconnected, keep the multimeter in AC position,
connect one terminal with the output breaker front-end phase-A of UPS 2, the other terminal connect
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