Puls ML15.051 Application Note

MiniLine

5V, 3A, SINGLE PHASE INPUT

ML15.051

25. APPLICATION NOTES

25.1. PEAK CURRENT CAPABILITY

Solenoids, contactors and pneumatic modules often have a steady state (sealed) 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 capacitive load.

Branch circuits are often protected with circuit breakers or fuses. In case of a short or an overload in the branch circuit, the protective device (fuse, circuit breaker) needs a certain amount of over-current to trip or to blow. The peak current capability ensures the safe operation of subsequent circuit breakers.

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. 25-1 Peak load 6A for 50ms, typ. Fig. 25-2 Peak load 15A for 5ms, typ.

5.1V

Output Voltage

5.1V

Output Voltage

2.4V

Output

10ms/DIV

Peak load 6A (resistive) for 50ms

Output voltage dips from 5V to 2.4V.

Current

15A

1ms/DIV

Peak load 15A (resistive) for 5ms

Output voltage dips from 5V to 0.8V.

0.8V

Output Current

25.2. BACK-FEEDING LOADS

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. (E

The maximum allowed feed back voltage is 6.3Vdc. The absorbing energy can be calculated according to the built-in large sized output capacitor which is specified in chapter 9.

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. However, please note that the output voltage can dip to zero for approximatelly 200ms if the back-feed voltage is removed.

lectro Magnetic Force).

25.3. INDUCTIVE AND CAPACITIVE LOADS

The unit is designed to supply unlimited inductive loads. The max. capacitive load depend on the steady state output current. At 3A output current, the output capacity should not be larger than 10 000µF at 1.5A output not larger than 25 000µF. In case of larger capacitors, the unit can show start-up attempts or start-up problems.

Dec. 2007 / Rev. 1.1 DS-ML15.051-EN All parameters are specified at 5V, 3A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

www.pulspower.com Phone +49 89 9278 0 Germany

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25.4. SERIES OPERATION

The power supply can be put in series to increase the output voltage.

Fig. 25-3 Schematic for series operation

Unit A

Unit B

Load

Earth

Instructions for use in series:

a) It is possible to connect as many units in series as needed,

providing the sum of the output voltage does not exceed 150Vdc.

b) 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. c) For serial operation use power supplies of the same type. d) Earthing of the output is required when the sum of the

output voltage is above 60Vdc.

Note: Avoid return voltage (e.g. from a decelerating motor or battery) which is applied to the output terminals.

ML15.051

5V, 3A, SINGLE PHASE INPUT

25.5. PARALLEL USE TO INCREASE OUTPUT POWER

Several power supplies can be paralleled to increase the output power. The ML15.051 has no feature included which balances the load current between the power supplies. Usually the power supply with the higher adjusted output voltage draws current until it goes into current limitation. This means no harm to this power supply as long as the ambient temperature stays below 50°C.

Fig. 25-4 Schematic for parallel operation

Unit A

Unit B

Load

Instructions for parallel use:

a) Use only power supplies from the same series (ML-Series). b) Adjust the output voltages of all power supplies to

approximately the same value (±50mV).

c) A fuse (or diode) on the output is only required if more than

three units are connected in parallel.

d) Ensure that the ambient temperature of the power supply

does not exceed 50°C.

Dec. 2007 / Rev. 1.1 DS-ML15.051-EN All parameters are specified at 5V, 3A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

www.pulspower.com Phone +49 89 9278 0 Germany

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