Datasheet

CPS20.241, CPS20.241-A1
C-Series
24V, 20A, SINGLE PHASE INPUT
24.5. PARALLEL USE TO INCREASE OUTPUT POWER
22/25
CPS20.241 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. 5%
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 30A or 32A 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.
24.6. 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 20A are paralleled to build a 80A redundant
system. For N+1 redundancy the same restrictions
apply as for increasing the output power, see also
section 24.5.
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 decoupling diodes or Mosfets, which are included in the redundancy module YR40.241 or YRH40.241.
I I
24V,20A
Load
YRH40.241
Redundancy
Module
Output
Input
1
Input
2
+
-
+
-
+
-
L
N
PE
Failure
Monitor
L N PE
CPS20.241
20A Power Supply
+ +
- -
24V, 20A
DC-
OK
Input
Output
L N PE
CPS20.241
20A Power Supply
+ +
- -
24V, 20A
DC-
OK
Input
Output
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.
May 2012 / Rev. 1.0 DS-CPS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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