Datasheet

CPS20.121
C-Series
12V, 30A, SINGLE PHASE INPUT
22.5. PARALLEL USE TO INCREASE OUTPUT POWER
23/26
CPS20.121 power supplies can be paralleled to increase the output power. The
output voltage of all power supplies shall be adjusted to the same value
(±100mV) in “Single use” mode with the same load conditions on all units, or
the units can be left with the factory settings. After the adjustments, the
jumper on the front of the unit shall be moved from “Single use” to “Parallel
use”, in order to achieve load sharing. The “Parallel use” mode regulates the
output voltage in such a manner that the voltage at no load is approx. 4%
higher than at nominal load. See also chapter 6. If no jumper is plugged in, the
unit is in “Single use” mode. Factory setting is “Single use” mode.
If more than three units are connected in parallel, a fuse or circuit breaker
with a rating of 40A or 50A is required on each output. Alternatively, a diode or redundancy module can also be
utilized.
Unit A
AC
DC
Unit B
AC
DC
-
+
-
+
Load
+
-
Energize all units at the same time to avoid the overload Hiccup
PLUS
mode. It also might be necessary to cycle the input
power (turn-off for at least five seconds), if the output was in Hiccup
PLUS
mode due to overload or short circuits and the
required output current is higher than the current of one unit.
Keep an installation clearance of 15mm (left / right) between two power supplies and avoid installing the power
supplies on top of each other. Do not use power supplies in parallel in mounting orientations other than the standard
mounting orientation (terminals on bottom of the unit) or in any other condition where a derating of the output
current is required (e.g. altitude, above 60°C, …).
Pay attention that leakage current, EMI, inrush current, harmonics will increase when using multiple power supplies.
22.6. PARALLEL USE FOR REDUNDANCY
Power supplies can be paralleled for redundancy to gain higher system availability. Redundant systems require a
certain amount of extra power to support the load in case one power supply unit fails. The simplest way is to put two
power supplies in parallel. This is called a 1+1 redundancy. In case one power supply unit fails, the other one is
automatically able to support the load current without any interruption. Redundant systems for a higher power
demand are usually built in a N+1 method. E.g. five power supplies, each rated for 30A are paralleled to build a 120A
redundant system. For N+1 redundancy the same restrictions apply as for increasing the output power, see also section
22.5.
12V
30A
Load
L
N
PE
Failure
Monitor
L N PE
+ +
- -
12V 30A
DC-
OK
AC Input
Output
CPS20.121
12-15V 30A
Power
Supply
I I
YR80.242
*)
Redundancy
Module
+ - + -
Input
1
Input
2
Output
*)
YR80.241
also possible
L N PE
CPS20.121
12-15V 30A
Power
Supply
+ +
- -
12V 30A
DC-
OK
AC Input
Output
Please note: This simple way to build a redundant system does not
cover failures such as an internal short circuit in the secondary side of
the power supply. In such a case, the defective unit becomes a load for
the other power supplies and the output voltage can not be maintained
any more. This can be avoided by utilizing redundancy modules, which
have decoupling devices (diodes or mosfets) included. Further
information and wiring configurations can be found in chapter 21.3.
Recommendations for building redundant power systems:
a) Use separate input fuses for each power supply.
b) Set the power supply into “Parallel use” mode.
c) Monitor the individual power supply units. Therefore, use the DC-
OK relay contact of the CPS20 power supply.
d) It is desirable to set the output voltages of all units to the same
value (± 100mV) or leave it at the factory setting.
e)
Apr. 2014 / Rev. 1.4 DS-CPS20.121-EN
All parameters are specified at 12V, 30A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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