• Burst and Surge 2 - a Comment

    Andre Moehl • 07/27/2015 at 07:08 • 0 comments

    Hello,

    because Andreas wrote a very good point into the comments to my last blog, I'd like to quote this completely. Seems, that something didn't became clear, I hope this will help now:

    Andreas

    I do compliance testing too. We have a "small" lab where i work with
the the basic equipment to do burst, surge, ESD, conducted emission and
conducted immunity tests, among others.

It is nice to see that others manage to burn out circuits with these fun tools too. :)

I'll try to help you a little bit with explaining the burst test. What you describe with "body charging up to a high voltage" does have nothing to do with the surge or burst test. Electrostatic discharge (IEC 61000-4-2) is a separate test with much higher voltages than burst or surge (usually 8kV for compliance, we test at 15kV where i work). The capacity and discharge resistor in the ESD test equipment are specifically modelled after the human body.

The burst test (IEC 61000-4-4) is more geared towards testing the immunity of your circuit against noise on the mains network. The signal is modelled roughly like the noise you can get from switching large loads (motors, heaters,...) on and off near your equipment. This generates a burst (like a packet) of high frequency voltage peaks usually in the region of 0.5-2kV amplitude. The burst test basically generates a controlled packet of these peaks, and your equipment gets bombarded with a lot of them for a given test period (5kHz or 100kHz repetition, usually for 1min per polarity).

Surge test (IEC 61000-4-5), as you have explained a bit better, is simulating the effect of a lightning striking the mains network at or near your equipment. This will usually result in a single fast (1.2us rise time at open circuit), high energy impulse (test voltages usually go to 2-4kV).
I hope this helps to understand the concept and idea behind these two tests a bit better.

    Thanks a lot, Andreas


  • Burst and Surge on a Power Supply

    Andre Moehl • 07/22/2015 at 09:22 • 0 comments

    Today I start with a few picture. Our product is charged by a external power supply.
    For a CE Test there is a Burst and Surge test obligatory. What is this ?

    Basically it is really simple. A test machine generates high voltage pulses which are conducts to the cable of the power supply. There are two things, which shouldn't happen then. The power supply shouldn't break and
    the voltage burst shouldn't go into the AC Line.

    When the burst reaches the AC Side from the power supply and goes into the AC grid it can disturb other machines or even kill them. The power supply itself can be destroyed and burn. You don't really want this.

    So, how can this happen in a normal household, that you can put a spark or a voltage burst on the cable.
    If you walk with rubber shoes over carpet or something, you get charged with really high voltage.

    Back to the supply. There is also another test. In this test, we send a burst from the AC Side into power supply,
    to see what's happen. It should not be broken. You shouldn't see anything on the output.

    A Surge test you can compare with a thunder which hits your house. Your machines are not directly hit, but surely broken too. What's happen there is that there will be a very high inductive field for a very short moment. This can destroy the electronic too. In this test this will simulate with some special generator.


    In our case, the power supply faild already the Burst test. Even it has a CE sign.