CS20.241, CS20.241-A1
C-Series
24V,
20A,
S
INGLE
P
HASE
I
NPUT
Preliminary
24.5.
P
ARALLEL
U
SE TO
I
NCREASE
O
UTPUT
P
OWER
Unit A
AC
DC
Unit B
AC
DC
-
+
-
+
Load
+
-
CS20.241 power supplies can be paralleled to increase the output power. They
can also be paralleled with power supplies from the DIMENSION CT, QS or QT-
series. 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.
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, …). Energize all units at the same time to avoid an overload-hiccup.
Pay attention that leakage current, EMI, inrush current, harmonics will increase when using multiple power supplies.
24.6.
P
ARALLEL
U
SE FOR
R
EDUNDANCY
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.
I
I
24V,20A
Load
YR40.241
Redundancy
Module
Output
Input
1
Input
2
+
-
+
-
+
-
L
N
PE
Failure
Monitor
L N PE
CS20.241
20A Power Supply
+ +
- -
24V, 20A
DC-
OK
Input
Output
L N PE
CS20.241
20A Power Supply
+ +
- -
24V, 20A
DC-
OK
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 decoupling diodes or Mosfets,
which are included in the redundancy module
YR40.241.
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 CS20 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.
Jan. 2012 / Rev. 0.5 DS-CS20.241-EN
Preliminary
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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