Momentary phase loss from POCO... How to deal with this?

[milemaker13]

Our facility has been experiencing this problem for several years. It is very intermittent and doesn't happen very often, maybe 4 times a year on average. Often enough to be very annoying to a production plant.

We get what seems to be a very brief phase loss that causes several minor production problems across the shop. It seems like it is different phases based on different equipment shutting down. Lights may flicker, chillers may drop out, compressors may shut off, other various production equipment & machines may shut down or alarm out, but they seem to be grouped as if A, B, or C is feeding the control power to different things.

We have looked at our service equipment several times never seeing anything of concern. Most recently it was both buildings that experienced the glitch, proving that it was POCO related (proving this time at least) as each building if fed from separate utility lines. Another reason to suspect POCO is that machines fed from separate services inside the building, but the same utility lines, are affected the same during each occurrence. And again, being that it is randomly different phases makes me think it is POCO related.

There is a large substation just up the road and I think it may be related to them switching things or some other such thing. Maybe?


Anyway, how should I go about investigating this? Its not a big emergency but we want to look into it. Should I call POCO (ComEd) and explain the issue?
How about inside our building? I plan to check tightness of the incoming lines during the next shutdown, and thought about using an IR thermometer to check temps in the mean time.

 

[mbrooke]

Best guess would be single phase reclosing. Often better than having everything go dark for a few seconds. I would let the POCO know they are having transient faults too often (for your requirements), but to be honest 4 times a year may not get them to do much.

 

[lukeiselectrician]

Typically the POCO can look back and see if they have had any intermittent outages. They may be able to track back and see if they have had any issues in your service range.

Another idea would be to look at metering the services for an extended period of time with a data logger. If you have any large equipment loads in your facility it is possible that you could cause phase imbalances at startup. I have encountered this on large compressor loads during drawdown or commissioning of equipment. The only way we determined what the main issues were, were going back through our readings after the fact. I know it is not ideal in your situation, due to the inconsistency, but I guess it would be somewhere to start.

 

[gadfly56]

Our facility has been experiencing this problem for several years. It is very intermittent and doesn't happen very often, maybe 4 times a year on average. Often enough to be very annoying to a production plant.

We get what seems to be a very brief phase loss that causes several minor production problems across the shop. It seems like it is different phases based on different equipment shutting down. Lights may flicker, chillers may drop out, compressors may shut off, other various production equipment & machines may shut down or alarm out, but they seem to be grouped as if A, B, or C is feeding the control power to different things.

We have looked at our service equipment several times never seeing anything of concern. Most recently it was both buildings that experienced the glitch, proving that it was POCO related (proving this time at least) as each building if fed from separate utility lines. Another reason to suspect POCO is that machines fed from separate services inside the building, but the same utility lines, are affected the same during each occurrence. And again, being that it is randomly different phases makes me think it is POCO related.

There is a large substation just up the road and I think it may be related to them switching things or some other such thing. Maybe?


Anyway, how should I go about investigating this? Its not a big emergency but we want to look into it. Should I call POCO (ComEd) and explain the issue?
How about inside our building? I plan to check tightness of the incoming lines during the next shutdown, and thought about using an IR thermometer to check temps in the mean time.

Install a PowerLogic CM4000TMG, or similar product at your MDP. It will catch the transients on the line side and preserve the kind of proof that the POCO can't shrug off.

 

[Jraef]

Install a PowerLogic CM4000TMG, or similar product at your MDP. It will catch the transients on the line side and preserve the kind of proof that the POCO can't shrug off.

The I-Sense does that too, then if you sign up for the web based grid monitoring service, it sends you a report on anyone else in your area on their system that had the same problem, meaning it proves it was not just your service. I've used it to argue that a peak demand charge was actually CAUSED by a very brief utility sag. The user got $127k back from PG&E, after they denied, denied, denied. Finally got to a manager level person and showed them the evidence, they had to pay up (actually, RETURN the money they had already been paid). That's rare, and took a LOT of perseverance on the part of the user, a transit authority with a big budget for stuff like this, so don't get your hopes up on a cash return. But you may be able to force them to do something about it.

 

[gadfly56]

The I-Sense does that too, then if you sign up for the web based grid monitoring service, it sends you a report on anyone else in your area on their system that had the same problem, meaning it proves it was not just your service. I've used it to argue that a peak demand charge was actually CAUSED by a very brief utility sag. The user got $127k back from PG&E, after they denied, denied, denied. Finally got to a manager level person and showed them the evidence, they had to pay up (actually, RETURN the money they had already been paid). That's rare, and took a LOT of perseverance on the part of the user, a transit authority with a big budget for stuff like this, so don't get your hopes up on a cash return. But you may be able to force them to do something about it.

Well, for $127,000 I can do a lot of "persevering", you betcha!

 

[Jraef]

Well, for $127,000 I can do a lot of "persevering", you betcha!

Yeah, it was motivating for them. I think the EE I was helping with it ended up getting a bonus for it. It’s a public agency though so it’s unlikely it was spectacular.