All parameters are specified at 24V, 2.5A, 230Vac input, 25°C ambient and after a 5 minutes run-in time unless noted otherwise.
Rockwell Automation Publication 1606-RM014A-EN-P — March 2014
21
Bulletin 1606 Switched Mode Power Supplies
21.8. Series Operation
Power supplies of the exact same type can be connected in series for higher
output voltages. It is possible to connect as many units in series as needed,
providing the sum of the output voltage does not exceed 150Vdc. Voltages
with a potential above 60Vdc are not SELV any more and can be dangerous.
Such voltages must be installed with a protection against touching. Grounding of
the output is required when the sum of the output voltage exceeds 60Vdc.
Avoid return voltage (e.g. from a decelerating motor or battery) which is
applied to the output terminals. Keep an installation clearance of 15mm (left /
right) between two power supplies and do not install the power supplies on
top of each other. Do not use power supplies in series in mounting
orientations other than the standard mounting orientation (input terminals on the bottom and output terminals on
top of the unit). Be aware that leakage current, EMI, inrush current and harmonics will increase when using multiple
power supplies in series.
Earth
Unit A
AC
DC
Unit B
AC
DC
-
+
-
+
Load
+
-
21.9. Operation on Two Phases
2
40V
+10%
max.
Fuse
L2
L1
L3
L
N
PE
Power Supply
AC
DC
internal
fuse
The power supply can also be used on two-phases of a three-phase-system.
A phase-to-phase connection is allowed as long as the supplying voltage is
below 240V
+10%
. Use a fuse or a circuit breaker to protect the N input. The
N input is not internally protected and is in this case connected to a hot
wire. Appropriate fuses or circuit breakers are specified in section 21.4
“External Input Protection”.
21.10. Use Without PE on the Input
From a safety standpoint, the unit is internally designed according to the requirements for Protection Class 1 and 2.
Please contact RA if you don't intend to use the PE terminal. A different marking of the front foil is then required.
Grounding of the input is beneficial for a high EMI immunity: symmetrical spikes or fast transients on the input side
can be conducted directly to earth by the built-in filter capacitors. The magnitude of such spikes or fast transients on
the output side caused by the input is much smaller than if you're not connecting this terminal to ground.
Fig. 21-5
Grounded input
Fig. 21-6
Ungrounded input
Surge
Y
X
L
N
Ground
Power Supply
+
-
Surge
X
L
N
Power Supply
+
-
24V
Spike