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 Post subject: Low Voltage CB with 2 seperate trips?
PostPosted: Mon Dec 09, 2013 12:24 pm 

Joined: Tue Mar 12, 2013 12:31 pm
Posts: 14
Location: Dallas, TX
Has anybody encountered this BBC breaker type before (picture: s3-4 main inside)? The breaker nameplate data is in pic2: s3-4-main nameplate. The breaker looks fairly common with an ABB trip unit but I happened to shine a flashlight beneath the breaker and found what I am guessing to be a completely separate trip unit attached to the bottom of the CB (pic 3: s3-4-1 trip 3). If anybody has had any exposure to this, information would be greatly appreciated. I am unable to discover anything relevant online. Thanks.


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PostPosted: Mon Dec 09, 2013 12:30 pm 

Joined: Tue Mar 12, 2013 12:31 pm
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Location: Dallas, TX
cant seem to get the pics to upload.


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PostPosted: Mon Dec 09, 2013 12:51 pm 

Joined: Fri Aug 10, 2012 11:47 am
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Josh Gatlin wrote:
cant seem to get the pics to upload.

I believe attachments have a 1mb size limit.


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PostPosted: Mon Dec 09, 2013 1:40 pm 
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If you can't resize the pics, perhaps you could upload them to something like photobucket and post a link?

You may be looking at some sort of shunt trip or undervoltage trip unit.

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PostPosted: Mon Dec 09, 2013 1:53 pm 

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Location: Dallas, TX
wbd wrote:
If you can't resize the pics, perhaps you could upload them to something like photobucket and post a link?

You may be looking at some sort of shunt trip or undervoltage trip unit.


Ahhh that is the reason. My public dropbox folder should do it..

https://www.dropbox.com/sc/o65gf9rygm6pyex/GiAiAyvym6


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PostPosted: Mon Dec 09, 2013 2:25 pm 
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Very interesting. What you have below are the original electromechanical trip units that came with the breaker. At some point the breaker had a solid state trip device retro fitted but in other breakers by other manufacturers these old trip units were always removed when the new trip unit was installed. Maybe these were left in place but disabled. Someone with experience on these specific units may comment.
Here is the manual and it shows both trip unit styles.

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PostPosted: Mon Dec 09, 2013 2:28 pm 

Joined: Tue Mar 12, 2013 12:31 pm
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Location: Dallas, TX
wbd wrote:
Very interesting. What you have below are the original electromechanical trip units that came with the breaker. At some point the breaker had a solid state trip device retro fitted but in other breakers by other manufacturers these old trip units were always removed when the new trip unit was installed. Maybe these were left in place but disabled. Someone with experience on these specific units may comment.
Here is the manual and it shows both trip unit styles.



This is what I was coming to the conclusion of. I have browsed through some breaker test sheets that were previously performed and noticed there wasn't a mention of any type of trip unit testing other than the ABB solid state trip. Thanks for the info @wbd


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PostPosted: Mon Dec 16, 2013 7:07 am 
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wbd wrote:
Very interesting. What you have below are the original electromechanical trip units that came with the breaker. At some point the breaker had a solid state trip device retro fitted but in other breakers by other manufacturers these old trip units were always removed when the new trip unit was installed. Maybe these were left in place but disabled. Someone with experience on these specific units may comment.
Here is the manual and it shows both trip unit styles.


That is exactly what happened here, there is no way to disable the OD's, the retrofit kit for the powershield comes with copper shunts to replace the OD's. Someone didn't know what they were doing here.

Side note to the OP, a second shunt trip is an available option on this breaker, just an FYI. But the one you have is a mess.


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PostPosted: Mon Dec 16, 2013 9:20 am 
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Josh Gatlin wrote:
This is what I was coming to the conclusion of. I have browsed through some breaker test sheets that were previously performed and noticed there wasn't a mention of any type of trip unit testing other than the ABB solid state trip. Thanks for the info @wbd


Did they do primary injection?


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PostPosted: Mon Dec 16, 2013 1:52 pm 

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Quote:
Did they do primary injection?


Test sheets didn't specify method of injection.


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PostPosted: Mon Dec 16, 2013 2:17 pm 
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They should. Few amps would be seconday injection, thousands of amps would be primary injection.

It looks like the INST setting on the OD's are around 6,000A. The INST plug on the power shield looks like it is maxed, can't see the setting or SS model in your photo but that setting is likely much higher than 6,000A, in which case it would be impossible to have testing the trip unit (Assuming they used that setting).

Here is the really weird thing, the OD trips are older than that breaker is. Looks to me like someone Frankenstiened a few different breakers to make that thing.


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PostPosted: Tue Dec 17, 2013 12:05 pm 

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Location: Dallas, TX
Quote:
They should. Few amps would be seconday injection, thousands of amps would be primary injection.


You're right. Primary Injected. The INST was tested at 19.2kA. So basically they are 'on' the breaker but aren't actually connected to the bus? The fact that they still look they are mounted is odd to me. At this point, I am continuing on using only the Solid State trip and disregarding the OD trip units.


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PostPosted: Wed Dec 18, 2013 6:16 am 
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Did you look at the test sheet and see if that the breaker tripped at the curve for the solid state trip device or on the old trip device curve? Should be on the test sheet I think although it has been a few years since I looked at test sheets.

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