ML60.121

MiniLine-2

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. The same situation applies when starting a motor or switching-on a capacitive load.

In many cases, the peak current capability also ensures a safe operation of subsequent circuit breakers. Branch circuits

are often protected with circuit breakers or fuses. In case of a short or an overload in a branch circuit, the fuse needs a

certain amount of over-current to trip or to blow.

Assuming the input voltage is turned on before such an event, the built-in large sized output capacitors inside the

power supply can deliver extra current. Discharging this capacitor causes a voltage dip on the output. The following

two examples show typical voltage dips:

Fig. 22-1 Peak loading with 2x the nominal

current for 50ms, typ.

Fig. 22-2 Peak loading with 5x the nominal

current for 5ms, typ.

18/23

10ms/DIV

Output

Voltage

Output

Current

12V

0A

9A

7V

12V

Output

Voltage

Output

Current

0A

1ms/DIV

22.5A

3.2V

Peak load 9A (resistive load) for 50ms

Output voltage dips from 12V to 7V.

Peak load 22.5A (resistive load) for 5ms

Output voltage dips from 12V to 3.2V.

Loads such as decelerating motors and inductors can feed voltage back to the power supply. This feature is also called

return voltage immunity or resistance against Back- E.M.F. (Electro Magnetic Force).

This power supply is resistant and does not show malfunctioning when a load feeds back voltage to the power supply.

It does not matter whether the power supply is on or off.

The maximum allowed feed-back-voltage is 25Vdc. The absorbing energy can be calculated according to the built-in

large sized output capacitor which is specified in chapter 5.

Nov. 2015 / Rev. 1.4 DS--ML60.121-EN

All parameters are specified at 12V, 4.5A, 230Vac 50Hz input, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

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Germany