How to Test Breaker through Current Injection Tester ?

[mask1290]

Can anyone please clarify how to use current injection Tester ? and during the testing how to setup the values of Isd Tsd long time pickup short time pickup

[GavinK5]

There are two types of test you can do: primary and secondary injection. Primary injection involves passing high current through the circuit breaker, replicating actual in service current levels at a low voltage. Secondary injection involves passing a very low current (less than 50A max) into the trip unit, bypassing the CT's - this requires a special injection tester.

Which type of test are you doing? Either way, you want to test your settings as close to their calculated value (determined by a coordination study) as possible. Also, what type of trip unit are you testing? Here are some generic settings you can try if you are unsure about what to set your trip unit at when testing:

LTPU: 1.0
LTD: somewhere in the middle (if 24 is max, go 12).
STPU: 4.0
STD: 0.200 OUT
INST: 6.0
GFPU 0.6
GFD: 0.200 OUT

Hope this helps!

[mask1290]

I want to learn primary injection testing through current injection tester and I wanna learn basic concept of it for example if I need to test long time pickup what should I have to see first and how can i start the test then long time delay how can I proof that long time delay is fine and working proper through current injection tester and so on like short time pick up ,short time delay instantenious .i will,wait for your reply

[GavinK5]

Ok here is a very basic rundown of how to perform each test:

Long Time Pickup: Usually this test is performed at 1.0X the rating plug, in this example we will say 1000A for simplicity. Start pushing current though the breaker at about 750A and slowly bring current up until the long time pickup indicator comes on, this should be around 1000A. Lower the current until the indicator drops out, and raise the current again until the indicator comes back on. Document this current value.

Long Time Delay: Set all other pickup values except long time pickup to maximum to prevent unwanted tripping. Delay bands are usually calibrated to 6X the current rating. Using the previous example this would be 6000A. So if your band is 24, it should take about 24 seconds to trip at 6X.

Short Time Pickup: Set all other pickup values except long time to maximum. Set all delays to maximum except short time, which should be set at 0.100 out. In this example we will test short time at 4X, which should be 4000A. Start with say 3000A and bring up current at a moderate speed until the breaker trips. Document this current value.

Short Time Delay: Set the short time delay to the desired band. Preset the test current to 1.5X the short time pickup. In the previous example that was 4000A, so test current should now be preset to 6000A. Reset the timer and push current, the breaker should trip within the specified time by the TCC, could be anywhere from 0.080 - 2.000+ seconds.

Instantaneous: Set to the desired pickup. In this example we will use 8X which would be 8000A. Start pulsing current from about 6000A and slowly increase the current value until the breaker trips. You must reset the timer after each pulse until the circuit breaker trips. Instantaneous trip time is usually 0.080 seconds or less. Document the current value and time when the breaker trips.

Perform each test on each phase. If you have ground fault you will need to defeat it either with a secondary test kit or by putting two poles in series. The test procedure is similar to the short time test. This is when things get complicated. Hope this helps.

[GavinK5]

You might also find this article to be helpful: http://testguy.net/content/197-Chara...d-Coordination

[mask1290]

Thanks a lot Gavin thanks for ur support you great.

[chaseh2006]

I would also recommend if your new to breaker testing in general to sit down and study "Time Current Curves" for multiple breaker manufactures, types, etc.

My first couple years sure I could test a breaker no problem but had issues understanding how to follow a curve (times and multipliers).

also if you ever go to test Short time delay or ground fault delay with the I2T function in the On position it will be more difficult to get the trip time within the band. It is a little bit more difficult but in my personal opinion if you learn how to run the high current test sets and understand how to read a time current curve you'll do just fine.

If you ever want time current curves one of the best places to find them is at: http://www.electricalmanuals.net/

Good luck!

[a.lallana@epsii.com]

Very good the only thing is that NETA recommends long time delay to be tested at 3x instead of 6x.

Ok here is a very basic rundown of how to perform each test:

Long Time Pickup: Usually this test is performed at 1.0X the rating plug, in this example we will say 1000A for simplicity. Start pushing current though the breaker at about 750A and slowly bring current up until the long time pickup indicator comes on, this should be around 1000A. Lower the current until the indicator drops out, and raise the current again until the indicator comes back on. Document this current value.

Long Time Delay: Set all other pickup values except long time pickup to maximum to prevent unwanted tripping. Delay bands are usually calibrated to 6X the current rating. Using the previous example this would be 6000A. So if your band is 24, it should take about 24 seconds to trip at 6X.

Short Time Pickup: Set all other pickup values except long time to maximum. Set all delays to maximum except short time, which should be set at 0.100 out. In this example we will test short time at 4X, which should be 4000A. Start with say 3000A and bring up current at a moderate speed until the breaker trips. Document this current value.

Short Time Delay: Set the short time delay to the desired band. Preset the test current to 1.5X the short time pickup. In the previous example that was 4000A, so test current should now be preset to 6000A. Reset the timer and push current, the breaker should trip within the specified time by the TCC, could be anywhere from 0.080 - 2.000+ seconds.

Instantaneous: Set to the desired pickup. In this example we will use 8X which would be 8000A. Start pulsing current from about 6000A and slowly increase the current value until the breaker trips. You must reset the timer after each pulse until the circuit breaker trips. Instantaneous trip time is usually 0.080 seconds or less. Document the current value and time when the breaker trips.

Perform each test on each phase. If you have ground fault you will need to defeat it either with a secondary test kit or by putting two poles in series. The test procedure is similar to the short time test. This is when things get complicated. Hope this helps.

[ElectricalTestTech]

Very good the only thing is that NETA recommends long time delay to be tested at 3x instead of 6x.

Yes, we typically test at 3x. Put NETA to the side for a minute. Why do you think NETA recommends a 300% test and not a 600% test. Most long time delays are expressed in a time delay @ 600% current. I know of one manufacturer that uses time bands which are not the same as a time delay @ 600%. This manufacturer is GE. But all the manufacturers test to 600% values. We as test techs want to prove that the curve is accurate so we run 300% tests. And in most cases, 300% current is a much easier magnitude to achieve than 600%.

Good luck