Datasheet

CT5.121

CT-Series

3-PHASE, 12V, 8A, 96W

22. APPLICATION NOTES

22.1. 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 examples show typical voltage dips for resistive loads:

Fig. 22-1 16A peak current for 50ms, typ.

(2x the nominal current)

Fig. 22-2 40A peak current for 5ms, typ.

(5x the nominal current)

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10ms/DIV

Output

Voltage

Output

Current

12V

16A

Output

Voltage

Output

Current

12V

1ms/DIV

40A

3.7V

Peak current voltage dips Typ. from 12V to 7V At 16A for 50ms, resistive load

Typ. from 12V to 7V At 40A for 2ms, resistive load

Typ. from 12V to 3.7V At 40A for 5ms, resistive load

May 2018 / Rev. 2.0 DS-CT5.121-EN All values are typical figures specified at 400Vac, 50Hz input voltage, 12V, 8A output load,

25°C ambient and after a 5 minutes run-in time unless otherwise noted.