S8VK-WA/S8VK-WB
28
S8VK-W
A
S8VK-WB
Common Accessories
Common Precautions
Parallel Operation
Parallel operation is used when the output current from one Power
Supply is insufficient for the load. Power Supplies are connected in
parallel to increase the output current. Two Power Supplies with the
same capacity can be connected in parallel.
You must meet the following conditions to use parallel operation.
• Standard mounting.
• Ambient temperature: -25 to +40°C
• Horizontal separation: 15 mm or more, Vertical separation: 23 mm
or more
• Rated input voltage range
Output voltage of 25 V max. (S8VK-W
@@@@
24)
Output voltage of 49 V max. (S8VK-WB
@@@
48)
• Adjust the output voltage difference of each Power Supply to 50
mV or less, using the output voltage adjuster (V. ADJ).
• There is no current balancing function for S8VK-X. A high output
voltage unit may work at overcurrent state and in this situation, a
life of a Power Supply will be extremely short. After adjusting the
output voltage, confirm the output current of the Power Supplies
balances.
• For Parallel Operation, to balance the current of the each unit, the
length and thickness of each wire connected to the load and each
unit must be same as much as possible.
• The output voltage may drop by several volts if the load changes
rapidly (e.g., if the load starts or is disconnected). Use the S8VK-R
or connect external diodes as shown in the figure.
For parallel operation with 240 W Power Supplies or S8VK-WB48048,
use the S8VK-R20.
• Do not use parallel operation when there is the possibility that the
input voltage will vary outside of the rated input range.
• Use the following information as a guide to the diode type, dialectic
strength, and current.
• Increase the output voltage setting of the Power Supplies by the
drop in the forward voltage (V
F
) of diodes D1 and D2. Also, the
diodes will cause a power loss equivalent to the Power Supply
output current (I
OUT
) times the diode forward voltage (V
F
).
Therefore, cooling measures must be implemented so that the
temperature of the diodes decreases to the catalog value or lower.
• Because of the load power and power loss due to the diodes, do
not exceed the rated power of one Power Supply (rated output
voltage × rated output current).
<Backup Operation>
Backup operation is possible if you use two Power Supplies of the
same model.
Even if one Power Supply fails, operation can be continued with the
other Power Supply.
Make sure that the maximum load does not exceed the capacity of
one Power Supply.
Use the S8VK-R or connect external diodes.
For backup operation with 240 W Power Supplies or S8VK-WB48048,
use the S8VK-R20.
• Use the following information as a guide to the diode type, dialectic
strength, and current.
• Increase the output voltage setting of the Power Supplies by the
drop in the forward voltage (V
F
) of diodes D1 and D2. Also, the
diodes will cause a power loss equivalent to the Power Supply
output current (I
OUT
) times the diode forward voltage (V
F
).
Therefore, cooling measures must be implemented so that the
temperature of the diodes decreases to the catalog value or lower.
• Because of the load power and power loss due to the diodes, do
not exceed the rated power of one Power Supply (rated output
voltage × rated output current).
Type
Schottky Barrier diode
Dielectric strength (V
RRM
)
Twice the output voltage or above
Forward current (I
F
)
Twice the rated output current or above
+V
-V
+V
-V
+V
-V
L1
L2
L3
L1/+
L2
L3/-
L1/+
L2
L3/-
S8VK-R
S8VK-W
S8VK-W
IN 1
IN 2
Load
+V
-V
+V
-V
L1
L2
L3
D
1
D
2
L1/+
L2
L3/-
L1/+
L2
L3/-
S8VK-W
S8VK-W
Load
Type
Schottky Barrier diode
Dielectric strength (V
RRM
)
Twice the output voltage or above
Forward current (I
F
)
Twice the rated output current or above
+V
-V
+V
-V
+V
-V
L1
L2
L3
L1/+
L2
L3/-
L1/+
L2
L3/-
S8VK-R
S8VK-W
S8VK-W
IN 1
IN 2
Load
+V
-V
+V
-V
L1
L2
L3
D
1
D
2
L1/+
L2
L3/-
L1/+
L2
L3/-
S8VK-W
S8VK-W
Load
