Gremlin in System

[dema]

I have my own ideas about what might be causing this, but would love to have other ideas as well.

A trucker hit a utility pole and 7 poles went down. One day later power was restored. Of seven business, one, business B, had to replace all their equipment and the others were able to get back to work. Business A however, has large electronic equipment which has continually malfunctioned. They have also found burned electrical outlets. All the malfunctioning equipment works intermittently, but the malfunctions are frequent to the point of heavily affecting their ability to function as a business.

What do you feel is the problem?

 

[big john]

Without knowing anything about how the services are wired all I can say for sure is you likely have an intermittent connection.

It's either an open phase causing intermittent voltage loss or an open neutral causing intermittent voltage shifts.

If the malfunctions are happening frequently enough this might be diagnosed as simply as putting a Fluke on the service with Min/Max enabled and seeing how far out of tolerance your voltages are.

Pictures or a more detailed description of the wiring?

 

[al hildenbrand]

I'd be looking for possible evidence that the Power Company primary line(s) came in contact with Customer secondary.

 

[Cavie]

I'd be looking for possible evidence that the Power Company primary line(s) came in contact with Customer secondary.

Didn't happen.

 

[meternerd]

Since the problem started after the pole deal, the utility might be willing to install a digital recorder to see if you have voltage problems. It will also record current, so you can see voltage drop as load increases.

 

[al hildenbrand]

Didn't happen.

WHAT didn't happen?

 

[GoldDigger]

WHAT didn't happen?

Read the quote. Primary to secondary line contact did not happen. Although how do you prove that if they were on the same pole?

 

[big john]

Read the quote. Primary to secondary line contact did not happen. Although how do you prove that if they were on the same pole?

If a whole lot of folks aren't replacing a whole lot of equipment, it's a pretty good bet that didn't occur. Primary contacts are wildly destructive.

His problem sounds like it's an ongoing issue with secondary voltage.

 

[al hildenbrand]

Read the quote. Primary to secondary line contact did not happen.

I've re-reread the OP, and I STILL don't see that said.

What I do read is that seven ( 7 ) poles went down. We have no information from the OP what is on the PoCo distribution side of the Customer's transformers. And I do deliberately type plural transformer.

The assumption that all of the businesses are on the same secondary and are supplied all from only one transformer bank, to me, is just that. An assumption.

Until the original poster provides more facts, I believe my suspicion of possible primary to secondary contact is reasonable.

 

[meternerd]

Ya know.....I was just thinking (dangerous, I know). What if the primary neutral is open or high impedance? That could definitely cause voltage problems on the secondary, and may only affect some of the customers depending on where their taps are. You might try getting the POCO out to do a bit more checking.

 

[dema]

Gremlin

Gremlin

My thought was a loss of ground reference when the pole was reinstalled. I did suggest getting a meter on the service - though I suggested an EC install one with the ability of tracking excursions of a few cycles. I wouldn't think that it would be the primary to secondary contact as the equipment still works, though unpredictably. Seems like that would fry it wouldn't it? They do have a black outlet box though. And one customer had everything electronic toasted.

Thank you.

 

[dema]

capacitors

capacitors

I'm wondering if there was capacitor switching nearby if it could have been damaged and be creating these Gremlins. Thoughts?

 

[al hildenbrand]

I wouldn't think that it would be the primary to secondary contact as the equipment still works, though unpredictably. Seems like that would fry it wouldn't it? They do have a black outlet box though. And one customer had everything electronic toasted.

Those points from your OP caught my attention.

Seven poles probably covers a lot of distance. . .but you have to provide those details. With the limited detail you've provided, I want to know more about the vehicle impact and how the force of a collision was transmitted down the line. Pure mechanics. Then I want to know how many transformer banks are involved, what the primary wiring is, and where the breaks occurred. Without any additional information, it is easy for me to imagine, at this moment, scenarios where a primary voltage contact occurred of very short duration in the midst of conductors being yanked and snapping and flailing about under high velocity.

I am also curious about the proximity of the various damages in the several businesses to the collapsed primary, and also in relation to what I suspect are separated sections of secondary.

A trucker hit a utility pole and 7 poles went down.

Does this mean only one pole was broken and the supply was lost to seven more poles? Or did a string of poles get toppled over?

Any video footage from area cameras may give hints, if not direct evidence. Police documentation, etc. will help.

My thought was a loss of ground reference when the pole was reinstalled.

Secondary grounded service conductors tend to be referenced several time to earth, and the Primary distribution circuit tends to use that same conductor as its return to source at the substation, or next supply transformer, and along that Primary circuit the grounded conductor will be solidly connected to earth multiple times. So the loss of an earth connection at the truck-hit-pole location would be unlikely to result in all the references becoming ineffective. However, the actual utility distribution practice, and the decades old history of this particular location will tell more of what the actual wiring, Primary and Secondary, is. A lot can be learned simply by visually examining the pole top wiring and reducing it to a circuit diagram.

 

[dema]

Conflict of interest

Conflict of interest

Due to a conflict of interest, I will not be hired to investigate this case. I've pretty much told you what I know and I very much appreciate the line of inquiry you recommend be followed. I will pass the information on to the engineer who does end up with the case. Thank you for your help.

 

[meternerd]

Those points from your OP caught my attention.

Seven poles probably covers a lot of distance. . .but you have to provide those details. With the limited detail you've provided, I want to know more about the vehicle impact and how the force of a collision was transmitted down the line. Pure mechanics. Then I want to know how many transformer banks are involved, what the primary wiring is, and where the breaks occurred. Without any additional information, it is easy for me to imagine, at this moment, scenarios where a primary voltage contact occurred of very short duration in the midst of conductors being yanked and snapping and flailing about under high velocity.

I am also curious about the proximity of the various damages in the several businesses to the collapsed primary, and also in relation to what I suspect are separated sections of secondary.



Does this mean only one pole was broken and the supply was lost to seven more poles? Or did a string of poles get toppled over?

Any video footage from area cameras may give hints, if not direct evidence. Police documentation, etc. will help.



Secondary grounded service conductors tend to be referenced several time to earth, and the Primary distribution circuit tends to use that same conductor as its return to source at the substation, or next supply transformer, and along that Primary circuit the grounded conductor will be solidly connected to earth multiple times. So the loss of an earth connection at the truck-hit-pole location would be unlikely to result in all the references becoming ineffective. However, the actual utility distribution practice, and the decades old history of this particular location will tell more of what the actual wiring, Primary and Secondary, is. A lot can be learned simply by visually examining the pole top wiring and reducing it to a circuit diagram.

My thinking was just the opposite. Ground reference is still there, but the neutral conductor is not, so normal return current is via the earth rather than the neutral. I have seen this very situation cause all kinds of weird issues from shocks in a shower to kids getting shocked on a fence to damaged equipment.

The primary neutral is very important for voltage stabilization, fault clearing, etc. Easy to miss a bad connection on a visual inspection. But, you are right....without more info, it's just a lot of techno-babble. The blackened receptacle causes me to agree that there was most likely a primary to secondary fault, but continuing problems may be something else.