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Please help me design a portable breaker tripping device

  1. Jan 9, 2013 #1
    Hi! Im going to be as brief as possible in this question.

    Im currently trying to design a portable breaker testing device that has a very simple mechanism. Basically, this device must be very small and should be able to fit into something like this:http://goo.gl/BuZ6U

    When I insert this device the amperage would probably shoot up to around 400-500 amps albeit for a split second before the breaker trips. However, this is probably enough to melt copper and maybe even iron.

    I want to known what type of switch i have to use to withstand the extraordinarily high current caused by an intentionally short circuit. Im going to install a rc delay module into this device as well so that when i press the switch it will cause a 2-3 second delay before the solenoid/relay activates. So what switch/relay should I use?

    Additionally, what types of wires should I use? A copper wire surely would not be strong enough to withstand such high temperatures and pressure cause by a short circuit. What materials should I use instead?

    Also, what substance should I use to coat the area around the wires to prevent the case from melting?

    I willing to speed a maximum of 500 dollars which should be more than enough to purchase some rare/expensive materials suitable for my purpose since I will using a very small amount of it.

    I estimate that the temperature would probably heat up to around 500-700 Celsius for a fraction of a second when in use.

  2. jcsd
  3. Jan 9, 2013 #2
    IF you are looking to trip a CB with the instantaneous function - you will not generate too much heat ( these typically kick in at 10X the breaker frame rating). If you want to trip over a time delay ( 120% of the rating) - then it may be more difficult. But for 400-500A for less than 1 Second can be carried by a surprisingly small conductor.
    The device you are looking to build would be dangerous - or at least using it would be. The Real problem is how does the device handle then the CB under test does not operate - how will your device survive / shut off, etc. The housing you show would be rather small to do what you are looking to do - but perhaps 2 - 3 x that size.I would still have it fused - or some other "solid" protection - and that alone will take up some space.
  4. Jan 12, 2013 #3
    Thanks for the response.

    Im planning to trip the CB with an instantaneous function, however, I will not be using any resistor which will probably cause the amperage to shoot up really fast. So even if the breaker trips at 10x the normal amperage, I believe it might exceed that limit (I could be wrong).

    I understand that this kind of device would be kind of dangerous. One of my solution is to program my device so that the relay automatically stops after 1 second. However, I can't seem to find any small relay that can withstand that much current and continuing to function properly. The ones I can find are too big for my purposes.

    Additionally, I previously stated that there will be a 2-3 second delay after the user activates it so that in the worst case, it will not explode in front of the user.

    Another option would be to use a fuse, but like you said, it will take too much space.

    Could you offer some advice on some other mechanism to shut it off in case it the CB fails to trip? If possible I would like it to be as small as possible. And if this matters, money is not really as issue for me.

    Thank you very much.
  5. Jan 12, 2013 #4


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    Gold Member

    You may find a suitable circuit design using an SCR static switch. Or a Triac static switch.
  6. Jan 14, 2013 #5
    Thanks! I have a quick question: Will configuring a TRIAC thyristor into a parallel arrangement help split the amperage between them evenly?

    For example, if I arranged 15 TRIAC thyristor rated at 10 amps each in a parallel configuration willit able to handle 150 amps altogether? Or is opening 15 thyristor simultaneously too risky since it might not activate at the same time causing too much current to pass to 1 or 2 TRIAC switch which might cause a domino effect that destroys all of the switches altogether?

    Again, Thank you very much for all your help.
  7. Jan 14, 2013 #6


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    Staff: Mentor

    If you are having to ask these questions on a web forum, you do not have the background to safely do this. Thread is locked.
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