User manual

QS10.121
Q-Series
12V, 15A, SINGLE PHASE INPUT
October 2006 / Rev. 1.0 DS-QS10.121-EN / All parameters are specified at 12V, 15A, 230Vac and 25°C ambient unless otherwise noted.
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20/22
27.7. PARALLEL USE TO INCREASE OUTPUT POWER
Power supplies can be paralleled to increase the output power.
Fig. 27-7 Schematic for parallel operation
Instructions for parallel use:
Unit A
AC
DC
Unit B
AC
DC
-
+
-
+
Load
+
-
a) Use only power supplies from the same series (Q-Series).
b) Adjust the output voltages of all power supplies to
approximately the same value (±500mV).
Otherwise, the DC-ok signal might not work properly.
c) A fuse (or diode) on the output is only required if more than
three units are connected in parallel.
d) Do not load terminals with more than 25A. Follow wiring
instructions according to chapter 27.9
e) Keep an installation clearance of 15mm (left/right) between
two power supplies and avoid installing the power supplies
on top of each other.
27.8. PARALLEL USE FOR REDUNDANCY
Power supplies can be paralleled for redundancy to gain a 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
Q-Series 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 10A are paralleled to build a 40A
redundant system.
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 - virtually nearly impossible - case, the defect unit becomes a load
for the other power supplies and the output voltage can not be maintained any more. This can only be avoided by
utilizing decoupling diodes which are included in the decoupling module YR2.DIODE.
Recommendations for building redundant power systems:
a) Use separate input fuses for each power supply.
b) Monitor the individual power supply units. A DC-ok lamp and a DC-ok contact is already included in the units
This feature reports a faulty unit.
c) When possible, connect each power supply to different phases or circuits.
d) It is desirable to set the output voltages of all power supplies to the same value to avoid a false DC-ok signal.
27.9. DAISY CHAINING OF OUTPUTS
Daisy chaining (jumping from one power supply output to the next) is allowed as long as the maximum current
through one terminal pin does not exceed 25A. If the current is higher, use a separate distribution terminal block.
Fig. 27-8 Daisy chaining of outputs
Fig. 27-9 Using distribution terminals
Power
Supply
+ + - -
Input
Power
Supply
+ + - -
Input
Load
+ -
max 25A!
L N PE
Power
Supply
+ +
- -
L N PE
Power
Supply
+ +
- -
Load
+ -
Distribution
Terminals