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Power Supply PS1000-A6-48.5
Application Notes
25
Application Notes
25.1
Peak Current Capability
The unit can deliver peak currents (up to several milliseconds) which are higher
than the specified short term currents.
This helps to start current demanding loads. Solenoids, contactors and pneumatic modules
often have a steady state coil and a pick-up coil. The inrush current demand of the pick-up coil
is several times higher than the steady-state current and usually exceeds the nominal output
current (including the PowerBoost). The same situation applies when starting a capacitive
load.
The peak current capability also ensures the safe operation of subsequent circuit breakers
of load circuits. The load branches are often individually protected with circuit breakers
or fuses. In case of a short or an overload in one branch circuit, the fuse or circuit breaker need
a certain amount of over-current to open in a timely manner. This avoids voltage loss
in adjacent circuits.
The extra current (peak current) is supplied by the power converter and the built-in large sized
output capacitors of the power supply. The capacitors get discharged during such an event,
which causes a voltage dip on the output. The following two examples show typical voltage
dips for resistive loads:
Figure 25.1
Figure 25.2
48V
10.8A
0A
10.8A peak current for 50ms , typ. (2x the nominal current)
48V
27A
0A
27A peak current for 5ms , typ. (5x the nominal current)
Output
Voltage
30.5V
Output
C urrent
10ms /DIV
Output
Voltage
25.3V
O utput
1ms /DIV
C urrent
35
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