Why do they both trip???
- Thread starter iwire
- Start date
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I guess not impossible. I would have to assume Bob has done some investigating of the loads supplied and would have likely found something if that is what is happening, but I have asked if a simple megger test has been done and haven't really gotten an answer either.
ptonsparky
Tom
- Occupation
- EC - retired
First post he indicated a basic mega test had been done.
Megger test is usually prior to commissioning a new install. This is existing installation. A fault could easily be ascertained per my last post.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
That was over 60 posts ago and is forgotten by now
That said, I can't recall ever needing to replace a conductor in such situations that passed a basic megger test, if it was replaced usually didn't solve any problems. Marginal failure of such test usually doesn't mean there will be high fault currents, it just means there is less time until you may have a "no-go" test.
From what little I have seen and heard, I'd certainly look into those magnetic trip settings before doing much else if it were my job to solve this. I'd probably do that before hiring a third party to monitor things.
If this has a pretty robust supply, available fault current is likley pretty high, magnetic trip set at it's lowest setting don't seem right in those conditions either. Just starting a motor across the line might briefly go into magnetic trip range easily in that situation.
- Location
- Massachusetts
That was over 60 posts ago and is forgotten by now
Try paying more attention the opening post instead of the side conversations.
Too tired right now to go into details right now.
- There was nothing advanced about this testing.
- The conductors and equipment passed the testing done by the testing company.
- They are curious about the mag trip settings as well.
- The 70 amp breaker tripped in a span of say 10 to 30 minutes from when we re-energized. None of us where in the area when it tripped.
- It was reset and did not trip again
- Location
- Massachusetts
What does that mean look into it? Can you do the calculations?
I sometimes really question if you read what has been posted.:huh:
No one is getting hired to monitor anything.
A company, that specializes in electrical conductor, equipment testing and commissioning was hired to look at the installation and give their professional opinion.
The technician on site took notes, photos, IR images, of many things, including the breaker settings and is going to put all that into a pretty report that will get turned into the customer for their in house engineers to use and base decisions on.
Next week I may well be back there cranking the settings but that will be an engineers call not mine.
This 200 amp breaker that is tripping is only one other 200 amp breaker away from the service disconnect. For all I know raising the mag trip on these breaker could just push faults up to the main. I am not quilfied to determine breaker settings.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I have never told you where to set them or how to determine their proper setting, I don't really know how to determine where to set them. I did think it looked a little suspicious as soon as I seen they were all at minimum settings and pointed that out, ever since then you seem to have been trying to prove I was wrong about something. Seems logical to me that any high inrush type of load can potentially give trouble with a low magnetic trip setting. Do you want to put line reactors on those circuits to reduce the inrush or do you want to figure out where to set the magnetic trip? Either way will involve some calculating of available current and impedances of circuits and loads.
I would not be one bit surprised if the mag trip of those three breakers is currently a lower value then all the fixed magnetic trip breakers in the panel, and if it were me I would have been addressing the setting of those somehow before going into much other study of what might be going on.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I have run into some odd things in the past that just baffled me. Many times the problem went away after some actions were taken, but no one really knew what action was the solution.
If these breakers are actually tripping at the same time, it suggests to me a common event.
I have been told that electronic breakers can be fooled into tripping. I have never seen it myself but I have been told that it can happen and it is very hard to determine just what caused it.
If these breakers are actually tripping at the same time, it suggests to me a common event.
I have been told that electronic breakers can be fooled into tripping. I have never seen it myself but I have been told that it can happen and it is very hard to determine just what caused it.
ptonsparky
Tom
- Occupation
- EC - retired
Try paying more attention the opening post instead of the side conversations.
- The 70 amp breaker tripped in a span of say 10 to 30 minutes from when we re-energized. None of us where in the area when it tripped.
- It was reset and did not trip again
Everything is normal then. Most things work just fine until you get down the road 10 to 30 minutes.
K8MHZ
Senior Member
- Occupation
- Electrician
Since the problem is intermittent, it may be prudent to do some sort of event monitoring. If you already have, please ignore this message.
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
You don't seem impressed by this testing company...
- Occupation
- Licensed Electrician
:? Why would you say this? Nothing iwire has said in this thread has given any indication of that.
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
It was just a question..... He mentioned a pretty little report for them to see and I though maybe he was not impressed. Sorry......
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Formatting counts. Usually more so than the data. Get with the program...
- Location
- Massachusetts
We put our PQ recording on it for a while, until we needed it for another job.
We did not catch a thing during that time. :weeping:
peter d
Senior Member
- Location
- New England
The solution is to keep the handle in the closed position with duct tape.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
K8MHZ
Senior Member
- Occupation
- Electrician
Observation effect? I'm only partly kidding.
Does your PQ gear record current? If so, how close to the breaker rating is it? For instance, is it 80% or 20%?
As for observation effect, it is possible that the installation of your recording equipment is mitigating the problem. I am thinking along the lines of a very brief transient that would be able to trip a mag breaker, but the recording gear keeps it from getting to the breaker by acting like a filter.
Are you planning to do any further monitoring?
- Location
- Massachusetts
20-30% very steady, no real load changes.
These panels only supply emergency lighting, exit signs, things like fire panels and other items the AHJ requires to be on an emergency panel.
There are other panels and ATSs for other optional generator loads.
Later I will post some more details, just not into it right now.
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