Multiple breakers tripping and hot to the touch

Status
Not open for further replies.
brantmacga

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
kwired said:
"Corrosion" is not so likely to be found, you need to look for discoloring, which would indicate overheating.
Click to expand...

That's what I was looking for and just didn't see it.


kwired said:
Again make sure you don't have 100 amp bus where you need 200 amp bus or something of that nature, or have exceeded maximum load on a individual pole space(es).
Click to expand...

I honestly don't know how I would tell the difference?? And this is in the 800A MDP. Looks the same as any other I've seen.


Thanks


Sent from my iPhone using Tapatalk
 
kwired

kwired

Electron manager
Location
NE Nebraska
brantmacga said:
That's what I was looking for and just didn't see it.




I honestly don't know how I would tell the difference?? And this is in the 800A MDP. Looks the same as any other I've seen.


Thanks


Sent from my iPhone using Tapatalk
Click to expand...
In OP it sounded like probably was a branch circuit panelboard, 800A MDP sounds more like a panel with primarily feeder breakers in it.

Maybe more details of exactly what you do have plus some load values would help quite a bit for others to understand what you have.
 
M

mwilson87a

Member
Location
Byron Center, Michigan
hmmm

hmmm

A few points (note I've not read all the replies yet...)

Are the fry tank heater elements of COIL TYPE, possibly packed in silica? or are they straight resistive elements. If they are coil types, you have an inductive situation and when you cycle the units off and on, you can get surge issues as with any inductive load.

As for the breakers, REPLACE THEM. Technically, the only test a breaker has to pass is to trip, reset, and trip once more. Breakers are mechanical devices and they will wear out after so many trips. If they are older, they may not be working properly. Additionally, if their seating in the panel is old/worn/not too tight, you will have issues.

Marc
 
J

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
mwilson87a said:
Technically, the only test a breaker has to pass is to trip, reset, and trip once more. Breakers are mechanical devices and they will wear out after so many trips.
Click to expand...
Not quite: the O-C-O test is only for short circuits at the full AIC rating of the breaker.
UL 489 has specific requirements for the number of no-load, full load, and 200% loading. Mechanically breakers can often last for hundred and hundreds of operations. For the most part a 'weak' breaker is more likely due manufacturing tolerances than it is to 'wear and tear'.
 
kwired

kwired

Electron manager
Location
NE Nebraska
jim dungar said:
Not quite: the O-C-O test is only for short circuits at the full AIC rating of the breaker.
UL 489 has specific requirements for the number of no-load, full load, and 200% loading. Mechanically breakers can often last for hundred and hundreds of operations. For the most part a 'weak' breaker is more likely due manufacturing tolerances than it is to 'wear and tear'.
Click to expand...
I was still in college and we got to tour Square D's plant where they made QO breakers (probably about 1988). I got to see that test (well got to listen to it behind heavy doors, and then see smoke roll out when they opened them after the test) at full AIC with three pole breaker with all three phases bolted together load side of breaker.

Was still too green to know the right questions to ask at the time but was still pretty interesting. I was pretty sure they don't do that test on every breaker but rather only at certain intervals as a QC method, because the breaker that had been tested, even though it did reset, did not look like something you would want to use again.
 
mgookin

mgookin

Senior Member
Location
Fort Myers, FL
kwired said:
I was still in college and we got to tour Square D's plant where they made QO breakers (probably about 1988). I got to see that test (well got to listen to it behind heavy doors, and then see smoke roll out when they opened them after the test) at full AIC with three pole breaker with all three phases bolted together load side of breaker.

Was still too green to know the right questions to ask at the time but was still pretty interesting. I was pretty sure they don't do that test on every breaker but rather only at certain intervals as a QC method, because the breaker that had been tested, even though it did reset, did not look like something you would want to use again.
Click to expand...

When you build something you test it to destruction to determine what you can get out of it.

We test our stuff at 10x ratings to determine a MTBF.

Something rated to a particular threshold only means it can sustain that threshold; it does not mean it will fail at threshold + 0.00001.

In fact it means it can sustain it for the rated magnitude for the prescribed load & life.
 
brantmacga

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
An update to this topic ......

Owner decided to have us replace the secondaries; we scheduled a shut down for today.
They brought in a reefer truck for all the food, had everyone take the day off.

Poco de-energized and turned the xfrmr over to us. Started disconnecting the secondary and found the C phase paddle was so loose it was spinning circles. ?

Poco said they had already checked it multiple times.

Anyway, owner said continue with replacing the secondary; we're this far in already. Everything was landed and torqued today, and they're coming back to energize tomorrow.

I think we will have the issue solved.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
So how much money do you figure this power company issue is costing your customer?

They should be upset and go after the POCO.
 
brantmacga

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
Multiple breakers tripping and hot to the touch

iwire said:
So how much money do you figure this power company issue is costing your customer?

They should be upset and go after the POCO.
Click to expand...

Gear is 20' from the transformer; the cost of replacing secondaries is $5k. Plus another $1400 for thermography. And add several trip charges when they called about the breakers tripping, so the total cost is probably around $7500.

That doesn't include other costs such as getting the reefer truck, labor for loading it, etc, and being shut down for two days. This store does a couple million per year, so they're losing a few grand in revenue.

We're also in the middle of a 4 week remodel here, but they were staying open while the work is being done. They used the downtime today to change out the kitchen ceiling and some other kitchen equipment; worked out nice for everyone else to have it shut down, otherwise they would've been in here at night doing the ceiling change.


Sent from my iPhone using Tapatalk
 
Last edited:
kwired

kwired

Electron manager
Location
NE Nebraska
Was the transformer lugs included in thermography? Guessing not.

Can't imagine that termination wasn't compromised during this, and a little surprised it doesn't look like it has been hot.

Add: maybe the worst damage is in an area hard to see.
 
brantmacga

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
kwired said:
Was the transformer lugs included in thermography? Guessing not.

Can't imagine that termination wasn't compromised during this, and a little surprised it doesn't look like it has been hot.

Add: maybe the worst damage is in an area hard to see.
Click to expand...

Not included ::::. In hindsight it should've been, but I was trusting the poco saying they had thoroughly checked their equipment.

We checked what was accessible to us on their side; primaries up the pole and the jacks.

Lesson learned


Sent from my iPhone using Tapatalk
 
Status
Not open for further replies.
Top