R90 ONLINE USER’S MANUAL UNINTERRUPTIBLE POWER SUPPLY (UPS)
Xtreme Power Conversion Corporation (Rev 3/7/14) Page 23
Requirements for a Parallel System
A group of parallel UPS modules behave as one large UPS system with the advantage of presenting
higher reliability. In order to assure that all modules are equally utilized and comply with relevant wiring
regulations, please follow the requirements below.
1. All UPS modules must be of the same rating and be connected to the same bypass source.
2. The Bypass and Utility input sources must be referenced to the same neutral potential.
3. The outputs of all the UPS modules must be connected to a common output bus.
4. The length and specification of power cables including the bypass input cables and the UPS
output cabinets should be the same size. This facilitates load sharing when operating in bypass
mode.
5. Up to 10 UPS modules may be paralleled with common battery if desired
Note:
If installing 5-6 units in parallel, remove the jumper cap J30 on the control inspection board
(MHTBJHR1CU04 in all UPS to be connected in parallel.
If installing 7-10 units in parallel, remove the jumper cap J30/J31 on the control inspection
board (MHTBJHR1CU04 in all UPS to be connected in parallel.
OPERATION
Operation Modes
The UPS is a double-conversion online UPS that may operate in the following alternative modes.
Normal Mode
The rectifier / charger derives power from the AC input utility and supplies DC power to the inverter
while floating and boost charging the battery simultaneously. The inverter then converts the DC power
to AC power and supplies the load.
Battery Mode (stored energy mode)
If the AC input utility power fails, the inverter, which is operating from power supplied by the battery,
supplies the critical AC loads with power from the batteries. There is no power interruption to the
critical load. The UPS will automatically return to Normal Mode when AC input utility recovers.
Bypass Mode
If the inverter is not functioning correctly, or if an overload occurs, the static transfer switch will be
activated to transfer the load from the inverter supply to bypass supply without interruption to the
critical load. In the event that the inverter output is not synchronized with the bypass AC source, the
static switch will perform a transfer of the load from the inverter to the bypass with power interruption
to the critical AC loads. This is to avoid paralleling of unsynchronized AC sources. This interruption is
To Next Page
Loading...
