Section III
Operation
006-0007097 02/14/2019
Rev E
25 of 52
UPS-1250DC Guide www.synqor.com
Power Cable Connections/Disconnections While Operating
For safety reasons, it is highly recommended that the input and output power cables be
connected to the UPS before the source of AC or DC input power is turned on, and before the
UPS is turned on (see Section I: Warnings and the SET-UP section above). Similarly, it is highly
recommended to first turn off the UPS and the sources of input power before any power cables
are disconnected from the UPS.
However, the SynQor UPS is capable of having any of its input or output power cables connected
at any time (if safely done), including when the UPS is turned on and delivering power to the
load. For instance:
• Even if the UPS is turned on, one can connect or disconnect the input power cables without
harming the UPS or disrupting power delivery to the load. If no input power source is
available, the UPS will draw power from the battery pack. When there is an external source
of power connected to the UPS, the unit will draw power from that source, choosing the AC
INPUT source first, if present, and then the DC input source. The transfer from one source of
power (including the battery) to another is seamless.
• Even if the UPS is turned on, one can connect or disconnect an output power cable without
harming the UPS or disrupting power delivery to a load that might be connected to the other
output.
NOTE that disconnecting an input or output power cable while that cable is handling
power will likely cause an arc to form as the terminals are pulled apart. This arcing is
not harmful to the UPS, although if done enough times it will degrade the connector to
the point where it will need to be replaced. This problem is particularly acute for the DC
INPUT cable because its current is so high. Disconnecting this cable while a large current
is flowing is not recommended.
ALSO NOTE that when the UPS is turned on and delivering power to a load, and then
another piece of equipment is connected to the same output, it is possible that this
connection will momentarily disrupt the quality of the UPS’s output voltage. If the UPS is
turned on and delivering power to several loads and then another load is connected, it is
possible that this new load will momentarily draw a large surge of current as it starts up.
If this happens, the output of the UPS could reach its maximum current limit, and the UPS
will reduce its output voltage to keep the current from getting any larger. This reduction
in voltage will be corrected once the new load reaches its normal mode of operation, but
in the mean time the reduction of the UPS’s output voltage might cause one or more of
the other loads to malfunction. Whether or not this will be a problem depends on the
characteristics of the various loads.