How to use a Power Supply to power a special load? (Capacitive load, inductive load, dynamic load, peak load)

Capacitive loads can be found under many different forms: capacitor banks, batteries, and even power supplies themselves are considered as capacitive loads. The principal issue that can appear on such type of load is at PSU start-up: a discharged capacitor basically acts like a short-circuit at start-up, hence it may overload the output.

One solution is either to add current limiting resistors in series with the capacitive load to limit the output current, or to select a power supply with “constant current limiting” overload protection type. This way, the power supply will automatically limit the current to a certain level stated in the specifications:

SPV-150 series specifications

For inductive loads, motors need high current at start-up, therefore a power supply with peak power capability is recommended (or a PSU with constant current limiting overload protection type).

The main issue of dynamic loads is output voltage drop. If the load step is too high in amplitude and too long, it may be able to completely discharge the output capacitors and then create a voltage drop or high ripple at the output. If the frequency of the load changes is high enough, this kind of issue is less likely to happen (please refer to the test reports for more information). One solution could be to put additional capacitors between Power Supply and load.

Some applications may need to draw short peak currents from the power supply. If the PSU overload protection type is hiccup or constant current limiting mode, then it will not be able to provide the current peak needed by the load. Some of our power supplies come with a peak power capability that makes them suitable for these kinds of applications. (e.g. HRP-150N series)

For open-frame power supplies with peak capability, the user should refer to the derating curves, and check the thermal requirements (a fan may be required).

Categories: Industrial, Medical, Operation
Tags: Capacitive Load, Constant Current Limiting, Dynamic Load, Hiccup Current Limiting, Inductive Load, Overload Protection, Peak Load

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