Reducing electrical usage for fairgrounds

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
Any-one have some idea’s on how to reduce a fairground facilities electric usage during off-season?

As those of us know, fairgrounds are often wired like a small city with many transformers in place to handle the load during a fair, all of which collectively is usually metered on the primary side just as it enters the facility. But during the off season all these transformers are constantly consuming some electric in an idle state ,yet enough it seems, to be very costly.

Over the years it’s been debated to just pull the cut-out on areas that do not need power in off season. But from what I hear that could be a potential problem as condensation can form in the transformer when taken out of service. And when cut-out is thrown back in ***** ban-go.

Is there any such thing as an auto-regulating current transformer that would create a high impedance when not called upon that would consume very low power during off season then adjust in response to high demand?

Any one here with utility experience have any suggestions?

Is it better to have more smaller transformers feeding smaller areas or larger transformers feeding larger areas and the impedance associated.....or is that just a wash.
Currently we have approximately 20 some transformers ranging from 50kva to 100kva
 

Besoeker3

Senior Member
Location
UK
Any-one have some idea’s on how to reduce a fairground facilities electric usage during off-season?

As those of us know, fairgrounds are often wired like a small city with many transformers in place to handle the load during a fair, all of which collectively is usually metered on the primary side just as it enters the facility. But during the off season all these transformers are constantly consuming some electric in an idle state ,yet enough it seems, to be very costly.
Can't these transformers turned off instead of left energised? A simple isolator on the primary of each.
 

steve66

Senior Member
My WAG would be that there is more use by loads that remain on than the transformers themselves.

Night lighting, emergency & egress lighting, heating, heaters to keep condensers from freezing, etc.

But then I have no idea where this even is.
 
Can't these transformers turned off instead of left energised? A simple isolator on the primary of each.
That is my thought. The op expressed concerns about the windings taking on moisture, however I don't think that is typically a concern for modern equipment and the deenergized time frames we are talking about. Perhaps someone with more knowledge in that area can confirm or deny that .

Say there are 1.5 meg of transformers, that would be theoretically 7.5 kw in no load losses, but could easily be twice that if these things are say 25 years old or older. (Quick and dirty numbers based in some measurements I've made).
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
In most POCO rate structures you would have demand billing for an account like this. If that is your case, in the off season you will still be paying demand charges based on your large demand month and any conservation efforts will be a small part of the bill.
 
I'm with Steve66, we don't know the loads or location (or voltages). Chances are that most transformers have at least a couple of year-round loads (security lights, a sump pump, etc). You could either re-circuit those loads to other transformers or add small ones to carry them, but that's a cost. So is driving around to pull/reset cutouts with the added possibility of a problem when they re-energize (bird/squirrel?).

How much money is involved (to save)?
 
In most POCO rate structures you would have demand billing for an account like this. If that is your case, in the off season you will still be paying demand charges based on your large demand month and any conservation efforts will be a small part of the bill.
Good point. One utility around here takes your demand and hits you with a demand charge of half that for the next 12 months even if you have less or even no load.
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
That is my thought. The op expressed concerns about the windings taking on moisture, however I don't think that is typically a concern for modern equipment and the deenergized time frames we are talking about. Perhaps someone with more knowledge in that area can confirm or deny that .

Say there are 1.5 meg of transformers, that would be theoretically 7.5 kw in no load losses, but could easily be twice that if these things are say 25 years old or older. (Quick and dirty numbers based in some measurements I've made).
Thart's what I would use as an estimate too; no-load losses of about 0.5% of rated. So if it's idle for 3/4 of the year, that's 6,570hrs x 7.5kW = <50kWH, so even at 11 cents/kWH you are looking at $5.5k/year, and if they are buying power at MV or HV and owning their own distribution they are likely paying less than that. $5.5k gets eaten up really fast if you have to replace anything, rewire anything or even run around disconnecting cutouts.

Remember, the current losses might look larger, but at no load the PF is very low and billing is based on WATTS, not VA.
 

oldsparky52

Senior Member
Thart's what I would use as an estimate too; no-load losses of about 0.5% of rated. So if it's idle for 3/4 of the year, that's 6,570hrs x 7.5kW = <50kWH, so even at 11 cents/kWH you are looking at $5.5k/year, and if they are buying power at MV or HV and owning their own distribution they are likely paying less than that. $5.5k gets eaten up really fast if you have to replace anything, rewire anything or even run around disconnecting cutouts.

Remember, the current losses might look larger, but at no load the PF is very low and billing is based on WATTS, not VA.
Wouldn't that be <50k kwh? Decimal 3 places to the left of where you had it?
 

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
I don't have an answer to your question, but I do have another question. How much money are we talking about?

It seems it's just the cost of business.
If memory serves me right, I think it is 2-3 thousand a month which includes some small events in the off season and the month’s billing for when the fair happens I think is around $60,000
 

kwired

Electron manager
Location
NE Nebraska
If memory serves me right, I think it is 2-3 thousand a month which includes some small events in the off season and the month’s billing for when the fair happens I think is around $60,000
Need to see what actual consumption is to know what you are being billed for.

As mentioned during off season, you may be paying a minimum charge just to cover having the capacity of service you have. It cost them to provide larger transformers and other equipment that sits idle most of the time, but are necessary to have when there is demand. If that is why the bill is high compared to amount of usage, it isn't going to go down much when you do turn off those idle transformers your minimum bill is high to start with even if you have no consumption in a particular month because of the way the cost is structured.

Might be best thing to find ways to have more events during those off months that can generate revenue to offset things.

My local fair has a relatively new exhibition building that was also designed and intended to be a an additional venue for others to lease during the rest of the year.
 

Iron_Ben

Senior Member
Location
Lancaster, PA
If memory serves me right, I think it is 2-3 thousand a month which includes some small events in the off season and the month’s billing for when the fair happens I think is around $60,000
This is an interesting situation. For us to really get our arms around the problem, it would so helpful for you to post a photo of the actual monthly bill, with all the charges broken out. Then we will know what the key contributors are. As noted above, it’s very possible that there is a minimum demand charge that the customer is hit with even if his demand for a given month is way under. That’s pretty standard practice. Also note that when a customer is primary metered like this, the energy charge is typically low. Ours was around $0.015 *plus fuel*, often totaling something like 6 or maybe 7 cents/kwh.

My educated guess is that these no load losses are not worth worrying about and that the transformers are better off staying energized. But a copy of the bill would be enlightening.
 

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
I’ll have to get back with ya’ll once I’m back from vacation and obtain some hard paperwork.
 

kwired

Electron manager
Location
NE Nebraska
This is an interesting situation. For us to really get our arms around the problem, it would so helpful for you to post a photo of the actual monthly bill, with all the charges broken out. Then we will know what the key contributors are. As noted above, it’s very possible that there is a minimum demand charge that the customer is hit with even if his demand for a given month is way under. That’s pretty standard practice. Also note that when a customer is primary metered like this, the energy charge is typically low. Ours was around $0.015 *plus fuel*, often totaling something like 6 or maybe 7 cents/kwh.

My educated guess is that these no load losses are not worth worrying about and that the transformers are better off staying energized. But a copy of the bill would be enlightening.
Even if not medium volts service, higher use services are mostly like that anyway - the demand charge is going to cover a certain amount of energy, they expect to be used. If not they collect anyway, they had to have the ability to deliver that demand all month long whether you used it or not.
 
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