Learning how to primary current inject breakers

[lazo2794]

hello to all,

I have 1 year testing experience and looking to further my advancement in the testing world. I want to learn how to primary inject breakers, this is for my own knowledge. I have watched a lot of videos on what to test but not how to test breakers. Ive helped secondary inject breakers, just not primary inject them. Is there a good video out there to help me really understand the trip curves, how much current to push, and how to set up the current injection test set. Thank you in advance.

[Kalbi_Rob]

hello to all,

I have 1 year testing experience and looking to further my advancement in the testing world. I want to learn how to primary inject breakers, this is for my own knowledge. I have watched a lot of videos on what to test but not how to test breakers. Ive helped secondary inject breakers, just not primary inject them. Is there a good video out there to help me really understand the trip curves, how much current to push, and how to set up the current injection test set. Thank you in advance.

Here's a link to Megger complete guide to Primary Injection Testing:

https://www.youtube.com/watch?v=qnaJhib5jQo

[SecondGen]

hello to all,

I have 1 year testing experience and looking to further my advancement in the testing world. I want to learn how to primary inject breakers, this is for my own knowledge. I have watched a lot of videos on what to test but not how to test breakers. Ive helped secondary inject breakers, just not primary inject them. Is there a good video out there to help me really understand the trip curves, how much current to push, and how to set up the current injection test set. Thank you in advance.

Setting up the test set properly is arguably the hardest part when it comes to primary-injection testing. First off you need a really good power source, so something like 100A of 480V. Then you need a good collection of copper bus, test cables, and c-clamps so you can connect to the breaker you are testing. Most drawout breakers can be connected directly to the stabs, but just about every insulated and molded case breaker is going to require you to get creative.

One trick I always like to use is short all phases on the load side of the breaker, that way you only move your line side lead when switching phases.

Once you have the breaker securely on the test set and a good power source, the testing will go smooth. If you want to keep the current level low and specs allow for it you can dial settings down for your timing tests at 3x 1.5x and instantaneous. I generally don't like going over 15kA so I will dial down whenever possible. Also you will get an arm workout from charging and closing the breakers all day, best to hookup control power whenever possible.

It's good to have the secondary set for the trip unit you are working with so that you can power the unit and defeat ground fault, if enabled. Some breakers can be defeated with a jumper, otherwise you will need to wire 2 phases in series.

[lazo2794]

Setting up the test set properly is arguably the hardest part when it comes to primary-injection testing. First off you need a really good power source, so something like 100A of 480V. Then you need a good collection of copper bus, test cables, and c-clamps so you can connect to the breaker you are testing. Most drawout breakers can be connected directly to the stabs, but just about every insulated and molded case breaker is going to require you to get creative.

One trick I always like to use is short all phases on the load side of the breaker, that way you only move your line side lead when switching phases.

Once you have the breaker securely on the test set and a good power source, the testing will go smooth. If you want to keep the current level low and specs allow for it you can dial settings down for your timing tests at 3x 1.5x and instantaneous. I generally don't like going over 15kA so I will dial down whenever possible. Also you will get an arm workout from charging and closing the breakers all day, best to hookup control power whenever possible.

It's good to have the secondary set for the trip unit you are working with so that you can power the unit and defeat ground fault, if enabled. Some breakers can be defeated with a jumper, otherwise you will need to wire 2 phases in series.


Thank you for that information. Also if i may ask, whats the best way to start testing the functions? Is there an order to test short time, long time, instantaneous and ground fault? Where is it beat to start

[Kalbi_Rob]

Thank you for that information. Also if i may ask, whats the best way to start testing the functions? Is there an order to test short time, long time, instantaneous and ground fault? Where is it beat to start

Most technicians will just go in order Long Time -> Short Time -> Instantaneous -> Ground Fault.

I personally will depend on the SCCS to determine the test procedure, because I always attempt to test settings in an order in which you will be able to leave the setting without disturbance as you progress through the different functions, to the best of your abilities.

In all reality there is no definitive way to test. That being said, be aware of Undervoltage trips, Zone Interlocks, Shunt Trips, Bell & Alarm circuits, and Maintenance switch modes (or other interlocks/features) as they create alternative difficulties to testing.