Power supply measurement tips (Part 3): High voltage AC circuit power-on test

    During the first power-up process, we first isolate the high voltage stage from the low voltage stage. We recommend using an AC power supply with current limiting . Once the AC power supply is selected, starting with the lowest AC voltage for the design is a critical step to help reduce the risk of major fuses, such as fuses caused by potential problems such as poor soldering, poor assembly, or PCB design errors.

    Now start measuring the AC input voltage and current. We recommend using appropriately rated differential and current probes. If you use a clamp-on current probe to measure the low AC input current drawn by an unloaded system, you will actually increase the current seen by the probe. To do this, simply loop the line conductor through the clamp multiple times. Remember to divide the current reading by the number of loops.

    Now you are ready to power up the device under test. But before you power up, use an oscilloscope or power analyzer on the AC input with the recording function enabled to ensure that you capture the inrush current and transient events. We recommend using the PA1000 Power Analyzer, which is optimized for fast, efficient, and accurate power consumption measurements. This power analyzer also offers an Inrush Current mode to test the peak value during the current inrush.

    A power analyzer, such as the PA1000, can easily perform AC circuit power-on testing.

    If you want to record the startup current, you can use a power analyzer with continuous recording function. This will help to preserve data in the event of a catastrophic failure during startup, so we strongly recommend this practice.

    Need more insight? Use DPOPWR Oscilloscope Software, which provides a comprehensive power analysis suite to help you measure and debug input AC power parameters during the power-up process.

    This is an example of AC power analysis using a DPOPWR or MSO5000B oscilloscope.

    Once the various items have been checked, the low voltage control circuit can now be enabled to gain a comprehensive understanding of the relevant information.