Merit to Power Conditioning Claims?

[YoungElectricalEng]

We are a facillity using ~15MW load. We have been approached by a company that claims 6%-12% energy savings by installing their power conditioning equipment. I'm curious to hear from the pro's if such claims have merit, and if this is worth looking into. My gut says snake oil. Note: We already have PF Correction.

Thanks in advance.

 

[YoungElectricalEng]

Sorry that is having a ~15MW load. Using ~15MW power.

 

[Hv&Lv]

Ask them to guarantee a 9% savings based on past and future bills. See how much they stammer and talk around the situation. If they are really that good there shouldn't be any problem guaranteeing their product.
I think your gut is right...

 

[jim dungar]

You save energy by turning things off, not by 'conditioning' the power.
You avoid penalty charges by conditioning your power.
What are the charges on your utility bill?

There are some companies that do offer legitimate power saving programs, but they are usually going to want to 'manage' your power usage not just sell you a device.

 

[YoungElectricalEng]

You save energy by turning things off, not by 'conditioning' the power.
You avoid penalty charges by conditioning your power.
What are the charges on your utility bill.

We have 16 different charges on our utility bill in Ontario (through an LDC). There are four categories. 1)Energy Based 2)Demand Based 3)Miscellaneous 4)Global Adjustment. Our PF is 0.91, and the only item listed, under Misc, as a penalty is for $8.50. Not a whole lot on a $400k/month bill.

Thanks Jim. I'll probably quote you to my manager as well!

 

[stevephillips]

We are a facillity using ~15MW load. We have been approached by a company that claims 6%-12% energy savings by installing their power conditioning equipment. I'm curious to hear from the pro's if such claims have merit, and if this is worth looking into. My gut says snake oil. Note: We already have PF Correction.

Thanks in advance.

Sounds like Grade A, High Definition, Special Edition Snake oil with authentic vinyl trim.

 

[charlie b]

Next time the person calls, try laughing in his face. :lol: Be sure to thank him for the entertainment. :happyyes:
OK, I wasn't serious about that. :happyno: But do not bother to give the person any of your valuable time.

 

[zbang]

But do not bother to give the person any of your valuable time.

OTOH, if they're buying lunch at a decent place, I'll listen to them while I'm eating. Then I'll ask for the performance guarantee.

 

[Cow]

I just wired my first ever power conditioner a week ago. So far I'm not impressed. This is a 208v single phase input with a 240/120v output. With 3 amps of load on the secondary, the primary draws around 23 amps. Basically at an idle. The transformer case is hot and the unit smells like an old wallpack ballast. And this thing is brand new.

I can't wait to see how hot it runs when we actually load it up closer to the 70 amps it's rated at. Plus it hums louder than any transformer I've wired.

Sorry, didn't mean to go off on a rant, but this was still on my mind since I just wired it....

 

[stevephillips]

Is it a ferroresonant transformer? They are rather inefficient and sometimes noisy however, they do provide pretty decent power.

 

[Jraef]

In general these things are a scam, but they propagate the scam by sprinkling in a few grains of truth, then blowing those out of proportion.

The "Power Conditioner" style energy savers are basing their claims on a few somewhat legitimate issues. One of them is that they "rebalance" the voltages in 3 phase systems, and that saves energy. It's one of those grains of truth, but over blown. The reason it's true is because 3 phase motors will over heat if the votlage is unbalanced, and that heat is energy that's being wasted. But they "rebalance" by just essentially reducing everything to the lowest common demominator, which itself can have other ramifications. All of their best claims are like that, they only tell you the PART of the story that supports their claims. Other stuff they say, such as the reduction of spikes being an energy saver, is just pure bovine excrement. Some of them also put in some caps to correct power factor, which (as discussed here numerous times) makes the AMP meter go down, but does nothning with regards to WATTS, which is what we are billed on. That's the oldest "energy saver" scam on the books.

 

[stevephillips]

In general these things are a scam, but they propagate the scam by sprinkling in a few grains of truth, then blowing those out of proportion.

Some of them also put in some caps to correct power factor, which (as discussed here numerous times) makes the AMP meter go down, but does nothning with regards to WATTS, which is what we are billed on. That's the oldest "energy saver" scam on the books.

I disagree to some extent. Installing equipment to make the power factor unity (1.0), will save energy thus save money. However, depending on the equipment being powered, the savings will vary widely. The purpose of power factor correction is to make the real power and apparent power values become equal so that reactive power is as close to zero as possible. If this is done, a customer will not only have to pay for the real power, but the reactive power as well. (the total of those is known as complex power)

Now, if the customer is running motors, transformers, more motors and ballast based lighting, power factor correction will save money. Keep in mind that most if not all modern ballasts have built in PFC caps).

When dealing with AC, watts are not a valid measurement of power unless your loads are purely resistive (PF=1). This is why transformers are rated in kVA. This unit figures in real power, reactive power and complex power into a value that is somewhat simple to work with.

DC is the only time that watts are a valid unit. Pulse DC is a different animal. Non linear loads such as computers and other office equipment fall under AC however, you start to have to factor in reflected impedance or else you can start melting transformer neutrals.

 

[Hv&Lv]

I just wired my first ever power conditioner a week ago. So far I'm not impressed. This is a 208v single phase input with a 240/120v output. With 3 amps of load on the secondary, the primary draws around 23 amps. Basically at an idle. The transformer case is hot and the unit smells like an old wallpack ballast. And this thing is brand new.

I can't wait to see how hot it runs when we actually load it up closer to the 70 amps it's rated at. Plus it hums louder than any transformer I've wired.

Sorry, didn't mean to go off on a rant, but this was still on my mind since I just wired it....

Have any idea of the no load losses? I would bet it uses more an no load than it would ever save.

 

[Hv&Lv]

When dealing with AC, watts are not a valid measurement of power unless your loads are purely resistive (PF=1). This is why transformers are rated in kVA. DC is the only time that watts are a valid unit.

How would you measure power if not in watts?

I was taught I*E*PF (or I*E*1.73PF) Was I taught wrong?

 

[stevephillips]

How would you measure power if not in watts?

I was taught I*E*PF (or I*E*1.73PF) Was I taught wrong?

I use a fluke 43b power analyzer. It tells me everything. Your formula figures in near worst case scenario of bad power factor. That is a good thing and I would continue using it.

 

[bob]

We have 16 different charges on our utility bill in Ontario (through an LDC). There are four categories. 1)Energy Based 2)Demand Based 3)Miscellaneous 4)Global Adjustment. Our PF is 0.91, and the only item listed, under Misc, as a penalty is for $8.50. Not a whole lot on a $400k/month bill.

Thanks Jim. I'll probably quote you to my manager as well!

Are you billed for kw or kva? Cost per unit? what is the demand?

 

[don_resqcapt19]

I disagree to some extent. Installing equipment to make the power factor unity (1.0), will save energy thus save money. However, depending on the equipment being powered, the savings will vary widely. The purpose of power factor correction is to make the real power and apparent power values become equal so that reactive power is as close to zero as possible. If this is done, a customer will not only have to pay for the real power, but the reactive power as well. (the total of those is known as complex power)...

The only actual energy that the customer saves by correcting the power factor is the small amount of I?R losses from the addition current on the conductors as a result of the reactive power. There may be more significant cost savings because of penalty billing for low power factor.

 

[Besoeker]

Your formula figures in near worst case scenario of bad power factor.

Incorrect.

The formula:

P = sqrt(3)V_LI_L cosφ

is valid for all power factors including unity.

 

[mike_kilroy]

1) I disagree to some extent. Installing equipment to make the power factor unity (1.0), will save energy thus save money. However, depending on the equipment being powered, the savings will vary widely.

2) The purpose of power factor correction is to make the real power and apparent power values become equal so that reactive power is as close to zero as possible. If this is done, a customer will not only have to pay for the real power, but the reactive power as well. (the total of those is known as complex power)

3) Now, if the customer is running motors, transformers, more motors and ballast based lighting, power factor correction will save money. Keep in mind that most if not all modern ballasts have built in PFC caps).

4) When dealing with AC, watts are not a valid measurement of power unless your loads are purely resistive (PF=1). This is why transformers are rated in kVA. This unit figures in real power, reactive power and complex power into a value that is somewhat simple to work with.

5) DC is the only time that watts are a valid unit. Pulse DC is a different animal. Non linear loads such as computers and other office equipment fall under AC however, you start to have to factor in reflected impedance or else you can start melting transformer neutrals.

1) your are wrong on this. as others have shown already, P=V*I*PF*1,73(if 3ph). no magic, nothing simplified here. Just the facts. You can see low PF's higher current draw is corrected to real current with PF factor included so KVA becomes real watts.

2) Customers do not pay for reactive power (unless they have PF penalty charge) since it is imaginary; any reactive CURRENT goes out to the power source (or PFC caps) and then next cycle it all comes back to the source. net result is 0 power.

3) see 1 & 2

4) power calcs ARE 100& accurate - that is why PF is included in the calculation. PF IS the reason xfmrs are rated in KVA since they have to pass the higher current that is imaginary power but real current.

5) pulse DC is no harder to calc power on that pure DC.. Just have to add it all up right.

As stated before also, yes, the CURRENT is higher, so there is more I2R losses due to it; that is why poco's sometimes charge for less than 1 PF - they have higher losses as this no- power current goes out to them and then is returned next cycle. the heating losses in the wires is real from it.

And reactive current does not go away or go to 0 with power factor correction; it is a physical current that must exist to make a motor a motor - it makes the background magnetic field; the PFC caps just give a nice close local source for it to circulate before it goes back to the poco.

 

[T.M.Haja Sahib]

The only actual energy that the customer saves by correcting the power factor is the small amount of I?R losses from the addition current on the conductors as a result of the reactive power.

If the customer owns a large size factory such as a paper mill, I?R losses due to low power factor is considerable.