Application: Inrush Current Simulation

What is Inrush Current?

While inrush current has a peak current value, the term “Inrush Current” is commonly used to describe the current that is required to energise an AC powered device or product when first applying voltage and power to it. This is especially true for inductive loads such as transformers, Inductors and electric motors. It also applies to AC/DC power supplies that use a simple rectifier/capacitor input stage. These initial currents can surge and be quite a bit higher than the normal operating current or what is called “steady state” current.

To address this challenge, Pacific Power Source has integrated a dedicated Inrush Current Web Browser Control into the AZX Series. This advanced mode applies to both Current Source and Electronic Load operation, enabling precise current control and realistic inrush current simulation.

Inrush Current Simulation Mode

This mode is used to similar AC inrush current behaviour of power factor corrected loads that take several cycles to adjust the current waveshape to obtain high power factor operation. The first few cycles (programmable by the user) will exhibit a typical diode bridge rectified AC waveform until a certain power level is reached where the power factor correction circuits start to take over.

The setup screen for the function allows full control of current levels, number of cycles, current waveform, repetitions, decay of peak current levels, PFC, Frequency and phase shift with respect to input voltage. The current inrush sequence consists of a decay section followed by a steady state section, the duration for each which can be programmed by the user. Simulation is therefore the most efficient and flexible approach, especially for complex or variable scenarios.

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