Section III
Operation
006-0007207 MPC-1250DC Guide
Rev F
20 of 44
03/03/2022
Power Cable Connections/Disconnections While Operating
For safety reasons, it is highly recommended that the input and output power cables be
connected to the MPC before the source of AC or DC input power is turned on, and before the
MPC is turned on (see Section I: Warnings and the SET-UP section above). Similarly, it is highly
recommended to first turn off the MPC and the sources of input power before any power cables
are disconnected from the MPC.
However, the SynQor MPC is capable of having any of its input or output power cables connected
at any time (if safely done), including when the MPC is turned on and delivering power to the
load. For instance:
• Even if the MPC is turned on, one can connect or disconnect the input power cables without
harming the MPC or disrupting power delivery to the load. If no input power source is
available, the MPC will shut down. When there is an external source of power connected
to the MPC, 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 to another
is seamless.
• Even if the MPC is turned on, one can connect or disconnect an output power cable without
harming the MPC 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 MPC, 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 MPC 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 MPC’s output voltage. If the MPC 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 MPC could reach its maximum current limit,
and the MPC 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 MPC’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.