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Electrical Safety Consideration While Performance Current Injection Test

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    Electrical Safety Consideration While Performance Current Injection Test

    Hello All,

    I'm interestion to know what exact safety concerns might happen in the scenario of primary and secondary injection testing respectively.

    It's my undetending that the main risk is arc flas on primary injections because this test add high current at low voltage level.

    I want to know your tought..


    Thanks.

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    Quote Originally Posted by Granyerd View Post
    Hello All,

    I'm interestion to know what exact safety concerns might happen in the scenario of primary and secondary injection testing respectively.

    It's my undetending that the main risk is arc flas on primary injections because this test add high current at low voltage level.

    I want to know your tought..


    Thanks.
    Maybe some slight sparking if the breaker or cables come off while testing. Essentially, there is no/very low danger.

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    Quote Originally Posted by Granyerd View Post
    Hello All,

    I'm interestion to know what exact safety concerns might happen in the scenario of primary and secondary injection testing respectively.

    It's my undetending that the main risk is arc flas on primary injections because this test add high current at low voltage level.

    I want to know your tought..


    Thanks.
    Your biggest risk of arc flash comes from connecting the high-current set to the power source. We usually supply ours with 100A 3p 480V. Like others have said, primary-injection is a low voltage, high current test, so the risk of electrical shock from the test set output is low.

    As for actual testing, the risk of arc flash is reduced, but still present at very high currents. If your connection points are not strong, its possible to produce sparks that can be fairly significant at currents above 1000A.

    You should also read the maintenance manual for whatever breaker you are testing because many times drawout breakers have specific size bus that must be used otherwise you risk a connection that is too loose, or a connection that will damage the breaker fingers from spreading too far.

    If you connections are too loose, its possible the breaker can come off the test set when pushing extremely high currents (like >10kA). I've had to literally strap breakers to the test set before when doing instantaneous testing on 5000A mains.

    You also risk overheating and damaging the current path if you do not properly apply current. I've seen finger clusters get burned many times. You will also want to be careful not to burn yourself when switching phases as the current test path will be very hot.

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    Quote Originally Posted by Granyerd View Post
    Hello All,

    I'm interestion to know what exact safety concerns might happen in the scenario of primary and secondary injection testing respectively.

    It's my undetending that the main risk is arc flas on primary injections because this test add high current at low voltage level.

    I want to know your tought..


    Thanks.
    First, I believe you would need a voltage level in excess of 50V to provide a situation for ARC FLASH (New NFPA will probably remove this requirement).
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    I have actually tested a 10,000A breaker at 300% (30,000A) and the measured voltage to ground was ~37V. That being said, every test set is designed differently, so I do encourage technicians to verify themselves. As stated before, the greatest threat to testers when it comes to Arc Flash is the input power supply for the test set and poor connections.
    Now, that being said, the way the hi-current test set was explained to me when I was starting was it is the same equipment used for arc welding. The difference between a welding machine and the current test set is the medium being used to make connection, as a welding machine uses a poor connection rod to heat metal, and the Hi-Current test set is solidly connected to minimize heating metal, and if use of the tables in NEMA AB4 are used, heating is minimized. I do realize that this isn't exactly how it works, but it did instill in me the importance of a solid connection to prevent welding our connections to breakers, or using our clamps as short circuits (as a co-worker proved with my clamp).
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    Quote Originally Posted by Granyerd View Post
    Hello All,

    I'm interestion to know what exact safety concerns might happen in the scenario of primary and secondary injection testing respectively.

    It's my undetending that the main risk is arc flas on primary injections because this test add high current at low voltage level.

    I want to know your tought..


    Thanks.
    The biggest concern for me is heat. Sometimes you do thermal breakers with high long time delay with cables and minimal contact. This can cause some heat up that can require some good gloves. I always try to find the best connection and surface area, but sometimes you have to trade proper rating for what's practical.

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