Rockwell Automation Publication 1606-RM056A-EN-P - December 2016
17
Basic Power Supply 10 A
Recommendations for building redundant power systems:
– Use the DC-OK signal contact to monitor the individual power
supply units.
– Use separate input fuses for each power supply.
– Use separate mains systems for each power supply whenever it is
possible.
– It is desirable to set the output voltages of all units to the same value
(± 100 mV) or leave it at the factory setting.
Series Operation
Power supplies of the same type can be connected in series for higher output
voltages. It is possible to connect as many units in series as needed, providing
the sum of the output voltage does not exceed 150V DC. Voltages with a
potential above 60V DC are not SELV any more and can be dangerous. Such
voltages must be installed with a protection against touching.
Earthing of the output is required when the sum of the output voltage is above
60V DC.
Avoid return voltage (for example, from a decelerating motor or battery) which
is applied to the output terminals.
Keep an installation clearance of 15 mm (0.59 in.) (left/right) between two
power supplies and avoid installing the power supplies on top of each other.
Pay attention that leakage current, EMI, inrush current, harmonics increase
when using multiple power supplies.
Figure 19 - Series Operation
Unit A
AC
DC
Unit B
AC
DC
-
+
-
+
Load
+
-
Earth
(see notes)