3 Phase Tripping Breaker

[mobiledynamics]

Riddle me this

3 Phase Panel

220V on Phase A/B

120V on Phase C


Incident One : Both above breakers were tripped. Did not pay no mind. Maybe a fluke. BRAND new buildout. 220V Breaker was changed

Incident Two 4 months later : Again, BOTH breakers tripped.
The loads on both breakers are not even near cap. On the 220, it's probably at 50% load and on the 120, maybe about 25-30% load.


Bearing it's happening twice, the second time was no coincidence . Any suggestions on what might have cause this.

 

[ard]

what kind of loads??

 

[Siegel1719]

Are you taking your measurements line to ground or line to line? If you are measuring line to line and you have a floating neutral you will get a false voltage reading. Always measure line to line and line to ground to verify voltage present.

 

[wyliesdiesels]

First of all, there is no more 220v in the US.

Is your system 240v D or 208v Wye?

What are the loads?

 

[mm08822]

Take readings phase - phase ...AB, AC, BC and each phase to neutral and post the 6 of them.

Is the "220"v circuit breaker 2 pole or 3 pole? Does this ckt contain a neutral wire?

 

[mobiledynamics]

The 120 has a neutral

Both circuits are 30 amps.

The 120 has about a 6-7amp load on it.
On the 220, I don't have the readings but it's definitely less than 20
220 has no neutral in the mix.

The panel is not mine...it's in our office space.
Long story short, electrician has no clue what's going on. He came back today to place a load on it (both the 120 and 240) and both of said breakers did not trip at all.

FWIW, the 2nd incident occured 2 1/2 - 3 months from the 1st incident. No change during that time in regards to the loads on both circuits.

He's stumped, I'm sorta ~over~ the whole fiasco and just look forwards to a resolution..
I have no clue on 3 phase. I can see how if the 120 was sitting on the same leg of one of the 220's, that it could have potentially tripped the leg ? But then again, the entire bus leg would be all tripped...

Help. Just looking towards a resolution
I can't even use another spark since it's the bldgs. ~preferred~ spark.

 

[mm08822]

Lots of q's already needing answered in order for anyone to provide you with solid answers. Otherwise it's going to be a thread of endless guessing.

 

[mobiledynamics]

MM. for clarity, can you extrapolate on post #5. thx

 

[mm08822]

In order to determine what 3 phase system is in place, voltage readings are a good starting point. These readings are taken across phases and also from each phase to neutral.
So let’s say the phases are labeled A, B, C and there is a neutral.
Phase to Phase:
Measure from A-B. voltage=______________.
Measure from B-C. voltage=______________.
Measure from C-A. voltage=______________.
Phase to neutral:
Measure from A-N. voltage=______________.
Measure from B-N. voltage=______________.
Measure from C-N. voltage=______________.

Is the “220v” circuit breaker 2 pole or 3 pole? (Is it a 3 phase load or single phase?)
What are the loads on each breaker that is tripping? Maybe get pics of load nameplates.
Are the loads cycling on/off, mostly off or mostly on, etc.
What are the actual loads for each – as measured with an amprobe, etc.

 

[BillK]

md,

What exactly are the loads on each breaker ? Lighting circuit ? Clothes dryer ? Oven ? Computers ? General receptacle circuit ? Etc etc ?

Was it during the day or at night ? Any chance there was a power surge of some type ?

I would forget about the fact that it is 3 phase, probably has nothing to do with your problem. Just troubleshoot it the same way as you would at home. I have 3 phase in my business and have had a couple of breakers go bad in the 20 years I have been there. If it keeps happening you might have to put some type of voltage monitor on it to see what is happening when the breaker trips.

 

[mobiledynamics]

On the 220, it's a big color copier.
On the 120, it's a UPS with a very small load on it..
Constant on the 120.
Varying load on the 220, since it's the copier.
It has tripped twice during the off hours, not when the copier is in use.

As crazy as this sounds, both times it has occured, it has been during the evening.
I literally have took all the loads on the 120 and put it on another 120V dedicated for now, until this gets squared away. The 120's are where my data racks are. I took them off the bad circuit until root cause get's figured out..

I don't have access to the panels myself.
Now that I type, I think while the copier vendor calls for a 20 amp circuit 220, the probe reading was around 3-4 amps when we took the the reading (aka, copier was idle at 7 in the morning), which is probably the same idle load when the breakers tripped - which is during evening/early morning

 

[wyliesdiesels]

*sigh*

It would be helpful to know system type.

Is the main service 480v then step down to 240D or 208Y with dry type transformer?

Could be overload, as said above, when voltage sag occurs.

Need to give us more info...

And again there is no such thing as 220v...

What brand of breakers? What brand and model panel?

Can you post some pics?

If you dont have access to panels, not sure how youre gonna get much help here.

 

[Norcal]

How can there be 220V & 120V???

It is possible for 127/220V but not standard.

 

[wyliesdiesels]

How can there be 220V & 120V???

It is possible for 127/220V but not standard.

Not in batman town...

OP profile says Gotham City

 

[matt_i]

Seeing as you don't have access to the panels is it possible there's more wiring that was scabbed on to the same circuits with loads you don't know about? The fact that they are tripping evening when potentially nobody is there hints at unexpected use.

That said, I've seen hardwood floor finishers do some pretty scary stuff, like stab #10 or 12 solid NM into a dryer receptacle, while hot, so they could run their sander....are there people in the office polishing floors or renovating at night (?)

 

[mobiledynamics]

Grrr.....still at this issue. Can't get the #'s from mm inquiry so the GJ brethern can help out. Nor much options, as the spark is the building electrician approved spark.

What are the remote chances, that it's incoming surges from the outside but the crazy thing coincidentally is that it's tripping the CB each time ? What befuddles me, is everytime it's tripped, I don't see any other CB's tripped at all. Could the surges be taking the path of least resistance and they are both the same paths the same time

In looking at my logs , with the disclaimer that UPS A (the problem one on Phase C).
When I look at UPS B (no idea which leg it sits)

On 12/20/1017 on UPS A, it was in ~trim~ mode, as it was logging too high voltage for almost 16 hrs.

When I look at the same log data on UPS B, nothing respective on the logs re: high voltage.

Just grasping at data I can see....even though breakers tripping, seem to be influenced from something external beyond my visibility

 

[FreddiFiche]

Not in batman town...

OP profile says Gotham City

Thanks for the coke that's now in my sinuses. You caught me at just the wrong time.

 

[American Locomotive]

Have you tried calling the POCO?

 

[mobiledynamics]

That's probably like 5 steps I'm heading in but ultimately, it's going to have to go through bldg. management. Granted the APC is designed to analyze and log this sorta data, me wonder how often and how high voltage fluctuations are.

 

[mm08822]

Does the House Sparky have a power monitor?
Start trending voltage and current on that ckt and leave it until the next occurrence.

 

[Lassen Forge]

My first suspect would be the UPS you have on one leg - those things are notorious for spikes and fluctuations. We replaced ours and our issues cleared up.

That or you have scabs coming in after hours, using the power for (fill in the project) with second rate equipment, and then leaving. Or the local homeless guy found an unlocked door and is plugging in his hot plate?

 

[mobiledynamics]

Problem is there is no load on the one I care about....the one that feeds the UPS. The ups is seeing the *data* on the line, but there is no load on the circuit. Not planning on putting anything on it till some level of root cause/action/id/correction is at least tried ya know.

Last time we saw a over volt. was about a month ago.
And I did call and ask, and spark say nay to said tools. I could lend him some of my fluke stuff....uggh, but what's that rule @ GJ about lending someone else your tools...

 

[mm08822]

Problem is there is no load on the one I care about....the one that feeds the UPS. The ups is seeing the *data* on the line, but there is no load on the circuit. Not planning on putting anything on it till some level of root cause/action/id/correction is at least tried ya know.

Last time we saw a over volt. was about a month ago.
And I did call and ask, and spark say nay to said tools. I could lend him some of my fluke stuff....uggh, but what's that rule @ GJ about lending someone else your tools...

Complain to whoever Sparky reports to and tell him to get the equipment or have your co rent it and let Sparky hook it up. Him doing nothing is holding up you doing your job.

 

[mobiledynamics]

10-4 on the mm. rewording the most recent post, but the high volt. spikes are not the root cause of the breakers tripping or potentially ? I mean that's the job of the ups, to deal with that, clean sine waves. etc.

Breakers tripping is either a thermal ingress cause by me overloading the circuit (which I'm fairly certain we're not) , so then the next potential would be something externally ?

 

[wyliesdiesels]

Grrr.....still at this issue. Can't get the #'s from mm inquiry so the GJ brethern can help out. Nor much options, as the spark is the building electrician approved spark.

What are the remote chances, that it's incoming surges from the outside but the crazy thing coincidentally is that it's tripping the CB each time ? What befuddles me, is everytime it's tripped, I don't see any other CB's tripped at all. Could the surges be taking the path of least resistance and they are both the same paths the same time

In looking at my logs , with the disclaimer that UPS A (the problem one on Phase C).
When I look at UPS B (no idea which leg it sits)

On 12/20/1017 on UPS A, it was in ~trim~ mode, as it was logging too high voltage for almost 16 hrs.

When I look at the same log data on UPS B, nothing respective on the logs re: high voltage.

Just grasping at data I can see....even though breakers tripping, seem to be influenced from something external beyond my visibility

A voltage surge would not cause a breaker to trip. Breakers care about overloads and overcurrent.

They dont monitor voltage. At let the ones you have...

Now breakers will trip with sags IF the voltage dips low enough to cause the connected load to draw too much current....

10-4 on the mm. rewording the most recent post, but the high volt. spikes are not the root cause of the breakers tripping or potentially ? I mean that's the job of the ups, to deal with that, clean sine waves. etc.

Breakers tripping is either a thermal ingress cause by me overloading the circuit (which I'm fairly certain we're not), so then the next potential would be something externally ?

Have you hooked up a clamp meter that has min max avg function and left it there for a few days to see if your equipment is pulling too much current?

 

[mm08822]

If nothing is on the UPS, then move it to another cb elsewhere. If it trips the "new" cb again, then I'd be inclined to point to the UPS.

The UPS should be able to clean up dirty power and output a very, very low distortion sine wave. Input cb's should not be tripping.
You don't know if dirty power is even present. Until a power analyzer is placed on the line and indicates significant distortion, I wouldn't assign this as the cause.

 

[wyliesdiesels]

Without some actual data about the power, we are just ******* into the wind and wasting time....

Get us some data using someone's meters....

 

[mobiledynamics]

Thx all. Will read and digest.

The initial breaker blip saga did not occur until 8 months after I moved in. No change on load on the circuit. Then it occured again, 5 months later. It's hard to duplicate the issue at hand (nor in the current state is it the same since I've taken the loads off the circuit in it's entirety). The only thing that circuit is doing right now is just keeping the batteries in a full SOC. The only constant I have not changed is leaving the 220 Copier circuit still plugged.

 

[mobiledynamics]

Just for discussion sake, let's say there was a short on the line - aka, multiple wires in pipe going to the panel. Would the short be chronic and fairly consistent or have ya'll seen where it sorta happens in this oddball frequency that is being discussed.

 

[wyliesdiesels]

If there was a short that was capable of tripping the breaker, you wouldnt be able to close the breaker without it instantly tripping again.

You really need to get a clamp meter or monitoring meter on that circuit. The data it gives will point you in the right direction.