Delta DPS-500K, User Manual, Page: 93 / 152

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7 UPS Operation
7.2 Parallel Units Operation Procedures
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Pre Start-up Warnings for Parallel Units
1. Make sure all switches including the circuit breakers or fuses of all external battery
cabinets are switched to the OFF position.
2. Ensure that the voltage difference between the Neutral (N) and the Ground ( ) is <
3V.
3. Check if the wiring is correct and the AC power source’s voltage, frequency, phase
and battery type meet UPS requirements.
4. Inspect if the auxiliary power fuse holder is closed. Please see Figure 7-2 .
P.S.
FUSE AC OUTLET
FUSE
AC OUTLET
220/230/240Vac,8A
O OFF
ON I
O OFF
ON I
O OFF
ON I
O OFF
ON I
BYPASS SWITCH INPUT SWITCH
MANUAL BYPASS SWITCH
OUTPUT SWITCH
Isolate Uninterruptible Power System (UPS)
Then check for Hazardous Voltage between all
terminals including the protective earth
See installation instructions before connecting to the supply
Apparatet er egnet for tilkopling til et IT forsyningsnett
RISK OF VOLTAGE BACKFEED
BEFORE WORKING ON THIS CIRCUIT
T S R N
UPS OUTPUT
T S R N
AC INPUT
R S T
BYPASS INPUT
240VDC 240VDC
BATTERY INPUT
N
(Figure 7-2: Close the Auxiliary Power Fuse Holder)
5. Before paralleling UPSs, please confirm that each unit’s capacity, voltage and
frequency are the same. After confirmation, use the provided parallel cable to
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Pre Turn-off Warnings for Parallel Units
1. If you want to turn off one of the parallel UPSs, please check whether the remaining
parallel UPSs’ total capacity exceeds the total critical loads. If the remaining parallel
UPSs’ total capacity is less than the total critical loads, it will be the bypass that
supplies power to the critical loads. Once a power event occurs, your critical loads
won’t be protected.
2. If you perform turn-off procedures for all parallel UPSs, all power supplies will
be completely cut off. Please make sure the critical loads connected to the
parallel UPSs have already been safely shutdown before you perform the turn-off
procedures.