FAQ No. FAQ01993
What is Backup operation?
Backup operation is used when the output
current from a single Power Supply is sufficient, but the system requires
protection (backup) by another Power Supply in case the first Power Supply
fails or is otherwise inoperative.
Use identical models for Power Supplies A and B.
Select the Power Supplies so that either one
can supply the required load capacity.
When connecting Power Supplies for backup
operation, always connect diodes (as shown in the diagram above) to
prevent the failure in one Power Supply from affecting the Power Supply
that is backing up operation. The following table shows the diode type,
dielectric strength, and current characteristics.
Schottky barrier diode
Dielectric strength (VRRM)
At least equal to Power Supplies' rated
Forward current (IF)
At least twice the rated output current
of Power Supplies
Increase the setting of the output voltages
of Power Supplies A and B by the forward voltage (VF) voltage drop of
diode's D1 and D2. Also, the diodes will produce a power loss equal to
Power Supplies' output current times the diodes forward voltage (IOUT ×
VF), so provide cooling so that the diode temperature remains below the
specified catalog value.
Any pair of Power Supplies can be connected
for backup operation except for Multi-output Power Supplies.
Other Power Supply
What size load (as a percentage of the Power Supply's rated output capacity) can be connected to an S82J or S82K Series Power Supply?
Are there models available that support parallel operation?
The output indicator turns ON, but then turns OFF immediately. What is the cause of the problem and solution (in models equipped with the overvoltage protection function)?