Qualification of electric product

Discussion in 'General Electronics Chat' started by nepdeep, Dec 13, 2012.

  1. nepdeep

    Thread Starter Active Member

    Sep 14, 2011
    Recently, I had an electronic project during my internship. I am in a pcb design phase now. After few weeks I should qualify the device. This is the first time I am doing qualification. What could be the major things to consider or how to test the following features.

    The product is kind of dc electric load.
    1. Load current max 22[A]
    2. Load Voltage max 20 [V]
    I hope I can do that with normal benchtop power supply ??

    3. Overtemp. protection- I have implemtnted overtemp. protection in the device, but how do I prove or test that condition on the lab....do i use some kind of heating deive or hot air blower.or...how do they normally test temperature.??

    Thanks to all those who help me build this product. I remember my first question on this forum when I started the project. Now I realise how naive and how strange was my understanding? at least I know something about opamps, current, voltage, power ratings, slew rates now. Thanks allaboutcircuits...
  2. JMac3108

    Active Member

    Aug 16, 2010
    Yes, you should definitely measure your overtemperature function.

    I assume you have some sort of temperature sensor that is located on your PCB near whatever you're using to sink the load current (probably mosfets)?

    You will need to measure the temperature on the temperature sensing device while increasing the temperature of your unit until the overtemperature shutdown occurs. You want to make sure that it occurs at the temperature you intended, that it actually occurs, that the system recovers when the temperature returns to normal, and that no damage occured to your circuit. The trick of course, is how to generate the overtemperature event.

    Is it possible to increase the load beyond the rated amount in order to heat up the circuit enough to trip the overcurrent without damaging the circuit? This would be the ideal way to test it since its closest to a real world condition.

    A lot of companies have a temperature chamber (such as a Thermotron) that is used to test/qualify hardware. You can use this is you have one.

    If all else fails, you may be forced to improvise with a heat gun or other external heat source.

    One more thing ...

    I said earlier to monitor the temperature on the sensor to ensure that the overtemperature function trips at the right teperature. But you should also measure the temperature on the power devices (mosfets) at the same time. You want to make sure that you've located the temperature sensor in a place that accurately reflects the temperature of the power devices that you're trying to protect. For example, what if your temperature sensor was too far away and the mosfets reached 125C while the temperature sensor was only reading 100C?

    You'll need thermocouples or one of those non-contact infrared temperature meters to measure the temperature on your devices.

    Hope this helps :)
    nepdeep likes this.