Application notes
PS1021-2405-0000
28
Version: 1.0
4
Application notes
4.1
Peak current capability
The device can deliver peak currents (for up to several milliseconds) that are higher than the specified short-
term currents.
This helps when starting loads with high current intensity. Magnetic coils, contactors and pneumatic modules
often have a stationary coil and a pick-up coil. The input inrush current requirement of the pick-up coil is
several times higher than the steady-state current and usually exceeds the rated output current. The
situation is exactly the same when starting a capacitive load.
The peak current capability also ensures safe operation of downstream circuit breakers of load circuits. The
load circuits are often individually fused with circuit breakers or fuses. In the event of a short circuit or
overload in a circuit, the fuse or circuit breaker needs a certain amount of overcurrent to open in time. This
prevents a voltage drop in adjacent circuits.
The additional current (peak current) is supplied by the power converter and the built-in large-size output
capacitors of the power supply. The capacitors are discharged during such an event, which leads to a
voltage drop at the output. The following two examples show typical voltage drops for ohmic loads:
Fig. 14: 10A peak current (ohmic load) for 50ms, the output voltage drops from 24V to 17V
Fig. 15: 25A peak load (ohmic load) for 5ms, the output voltage drops from 24V to 9V.
