High Voltage Imbalance Penalties

[franklinmanklin]

We are looking into something that a salesman is trying to sell us. I don't know much about it since I am merely a bystander but is there any merit to this? I was under the impression that we are billed via each leg and didn't know there was an increase in usage with an imbalance. Power factor is one thing but this is different. Anyone have any experience with this?

 

[John120/240]

Does the term snake oil sound familiar ?

 

[franklinmanklin]

That was my first thought as well. However, if the numbers are proven then I am at a loss. The problem lies in the fact that the usage is never the same so you cannot get an accurate comparison.

http://energysolutionsplus.net/products/power-conditioning-systems-pcs/

 

[charlie b]

Numbers prove nothing, if they are provided by the company trying to make a sale. They completely lost my attention when I saw their graphic that showed a load imbalance being corrected by their device. That is not physically possible, unless their device includes a load bank that will add load to the more lightly loaded phases. That, of course, would constitute an increase in load, and a higher bill will result. Also, I do not believe that a utility will charge a penalty for a load imbalance over a certain percentage. I echo the "snake oil" opinion.

 

[jim dungar]

All major utilities are interested in reducing their loads and therefore their customers' bills.
For them it is cheaper to loose money due to an energy saving device, than it is to find additional generation capacity.

Call your utility, ask them what charges actually make up your monthly bill.
Ask what portions of your bill can be cost effective to address.

 

[kwired]

Do you get more heat when burning $100 bills in the fireplace than if you burn same number of $1 bills?

 

[K8MHZ]

Does the term snake oil sound familiar ?

Did you even look at the product? It's a power conditioner, like the one Eaton sells:

http://powerquality.eaton.com/Products-services/Power-Conditioning/default.asp

Only with more options.

It's clearly stated that the unit is designed for industrial applications. It is not the same thing as the scam devices sold for residential use.

Perhaps the salesperson is over selling the device, but there is merit to installing them in certain industrial situations. I suggest that the OP consult an electrical engineering firm to determine what the ROI and other merits of power conditioning would be, but brown out protection alone could save a company big, big bucks. If it is deemed that a power conditioner is viable, then go shopping. PCS isn't the only one making these.

 

[wirenut1980]

Did you even look at the product? It's a power conditioner, like the one Eaton sells:

http://powerquality.eaton.com/Products-services/Power-Conditioning/default.asp

Only with more options.

It's clearly stated that the unit is designed for industrial applications. It is not the same thing as the scam devices sold for residential use.

Perhaps the salesperson is over selling the device, but there is merit to installing them in certain industrial situations. I suggest that the OP consult an electrical engineering firm to determine what the ROI and other merits of power conditioning would be, but brown out protection alone could save a company big, big bucks. If it is deemed that a power conditioner is viable, then go shopping. PCS isn't the only one making these.

While I agree with you that power conditioners can be beneficial in certain situations, the website also clearly states it can save you energy by balancing the load, reducing phase current, and reducing negative sequence voltage. I would like to hear how they can make that claim. Utilities do not penalize for unbalance (at least none that I know of). 3 phase metering looks at all 3 phases, so it is not like there are savings from lowering the "high" phase current that is being measured by the meter.

Over-selling? I would say it is more like flat out lies. Kind of sounds like snake oil to me too.

 

[brian john]

I do know they are right down the street from the assembly shop for the Washington area, other than that it may work but the web site screams hack (to me).

 

[Jraef]

While I agree with you that power conditioners can be beneficial in certain situations, the website also clearly states it can save you energy by balancing the load, reducing phase current, and reducing negative sequence voltage. I would like to hear how they can make that claim. Utilities do not penalize for unbalance (at least none that I know of). 3 phase metering looks at all 3 phases, so it is not like there are savings from lowering the "high" phase current that is being measured by the meter.

Over-selling? I would say it is more like flat out lies. Kind of sounds like snake oil to me too.

Let me start by making it clear I too think this is another snake-oil outfit. The way they keep repeating the same information in different ways is a tactic used by people who have nothing to sell, but they figure that if they make it LOOK like it is doing a lot of different things, buyers might accept maybe 50% as truth and think it is worth at least something, meaning that if you have 2 features and 50% are true, then it seems a lot less valuable than something that has 12 features and 6 of them are true. So they repeat the same 2 features 6 times each and change up the wording a little each time. Classic snake oil.

But the one issue that sort of rings true is the phase balancing issue. There are a few of these power conditioners that are providing this. I think it is nothing more than a type of zig-zag transformer, but I've never seen one or even an internal diagram of one to know for sure. A company called Mirus started selling this concept maybe 15 years ago or so and I bought some for harmonic mitigation on VFD systems. They did work for that, but they were really no better than a reactor as far as I could tell. Mirus also laid claim to voltage balancing, but I never needed that so I can't attest to it.

However, when you do have a voltage imbalance on a 3 phase motor, you do get negative sequence current flowing in the rotor. That negative sequence current circulating in the rotor cage then creates torque that opposes the normal torque in the motor, essentially making the motor fight itself just a little bit. You don't really notice of course because all you see is the net resultant positive torque. But for each amp of current flowing to the motor, you are getting a net lower amount of working torque from it. The added energy is heat in the motor. That is what is behind the need for phase imbalance protection in a motor, the current flowing to the motor might be below the FLC setting of an overload protection device, but the HEAT created by that current may end up burning it up without ever tripping the OLR. That heat is all waste, so if you can balance the voltage and current, you are going to save a little energy. How much is of course completely subjective and damned near impossible to quantify. Whether or not this system really does that is something I can't say, but they are not the only ones claiming it is possible and I have read an independent article on line somewhere attesting to it. If I can find it I'll post a link.

franklinmanklin,
To address your question as asked / implied, utilities do not bill you on individual phase currents and they do not assess penalties for imbalance. You may end up PAYING for it indirectly as I outlined above, but if that salesman said or implied you get a direct penalty, that's further evidence that he is a fool or a liar, neither of which should be suffered.

 

[Phil Corso]

Franklinmanklin...

Having been involved with an investigatiion of so-called "Energy-Saver" and "Electrical Performance Enhancing" devices while with Florida's EPA, there is a very simple way of determining if they are legit or not... just read the small-print! Especially the part about documentation necessary to challange the "contractual" Warrantee!

Regards, Phil Corso

 

[robbietan]

However, when you do have a voltage imbalance on a 3 phase motor, you do get negative sequence current flowing in the rotor. That negative sequence current circulating in the rotor cage then creates torque that opposes the normal torque in the motor, essentially making the motor fight itself just a little bit. You don't really notice of course because all you see is the net resultant positive torque. But for each amp of current flowing to the motor, you are getting a net lower amount of working torque from it. The added energy is heat in the motor. That is what is behind the need for phase imbalance protection in a motor, the current flowing to the motor might be below the FLC setting of an overload protection device, but the HEAT created by that current may end up burning it up without ever tripping the OLR. That heat is all waste, so if you can balance the voltage and current, you are going to save a little energy. How much is of course completely subjective and damned near impossible to quantify. Whether or not this system really does that is something I can't say, but they are not the only ones claiming it is possible and I have read an independent article on line somewhere attesting to it. If I can find it I'll post a link.

NEMA standard for motors say that a 3% voltage supply unbalance can take away 10% of your motor's efficiency, which is why utilities (in the Philippines for example) are mandated by law to have a max unbalance of 2.5% measured at the PCC.

in this context, it is the utilities that get penalized if they exceed the voltage unbalance limit set by the govt.

 

[kwired]

NEMA standard for motors say that a 3% voltage supply unbalance can take away 10% of your motor's efficiency, which is why utilities (in the Philippines for example) are mandated by law to have a max unbalance of 2.5% measured at the PCC.

in this context, it is the utilities that get penalized if they exceed the voltage unbalance limit set by the govt.

Isn't voltage balance going to be somewhat dependent on load balance? Utility can only do so much on their side, if customer has large load on only one or two phases isn't that going to draw the voltage down on those phases? If the next customer down the road has a heavy imbalance the first customer may see some effects of it.

 

[weressl]

We are looking into something that a salesman is trying to sell us. I don't know much about it since I am merely a bystander but is there any merit to this? I was under the impression that we are billed via each leg and didn't know there was an increase in usage with an imbalance. Power factor is one thing but this is different. Anyone have any experience with this?

There is one way that balancing can be accomplished and that is a fully rated AC/DC/AC converter. I doubt that the cost of the inverter and the efficiency loss of the conversion would ever result in a positive cashflow.

 

[weressl]

Did you even look at the product? It's a power conditioner, like the one Eaton sells:

http://powerquality.eaton.com/Products-services/Power-Conditioning/default.asp

Only with more options.

It's clearly stated that the unit is designed for industrial applications. It is not the same thing as the scam devices sold for residential use.

Perhaps the salesperson is over selling the device, but there is merit to installing them in certain industrial situations. I suggest that the OP consult an electrical engineering firm to determine what the ROI and other merits of power conditioning would be, but brown out protection alone could save a company big, big bucks. If it is deemed that a power conditioner is viable, then go shopping. PCS isn't the only one making these.

A plain power conditioner will still reflect the imballance on the line side, it will adjust the individual phase outputs, and that is all it can do besides of filtering out some line noise and blocking some spikes.

 

[weressl]

Let me start by making it clear I too think this is another snake-oil outfit. The way they keep repeating the same information in different ways is a tactic used by people who have nothing to sell, but they figure that if they make it LOOK like it is doing a lot of different things, buyers might accept maybe 50% as truth and think it is worth at least something, meaning that if you have 2 features and 50% are true, then it seems a lot less valuable than something that has 12 features and 6 of them are true. So they repeat the same 2 features 6 times each and change up the wording a little each time. Classic snake oil.

But the one issue that sort of rings true is the phase balancing issue. There are a few of these power conditioners that are providing this. I think it is nothing more than a type of zig-zag transformer, but I've never seen one or even an internal diagram of one to know for sure. A company called Mirus started selling this concept maybe 15 years ago or so and I bought some for harmonic mitigation on VFD systems. They did work for that, but they were really no better than a reactor as far as I could tell. Mirus also laid claim to voltage balancing, but I never needed that so I can't attest to it.

However, when you do have a voltage imbalance on a 3 phase motor, you do get negative sequence current flowing in the rotor. That negative sequence current circulating in the rotor cage then creates torque that opposes the normal torque in the motor, essentially making the motor fight itself just a little bit. You don't really notice of course because all you see is the net resultant positive torque. But for each amp of current flowing to the motor, you are getting a net lower amount of working torque from it. The added energy is heat in the motor. That is what is behind the need for phase imbalance protection in a motor, the current flowing to the motor might be below the FLC setting of an overload protection device, but the HEAT created by that current may end up burning it up without ever tripping the OLR. That heat is all waste, so if you can balance the voltage and current, you are going to save a little energy. How much is of course completely subjective and damned near impossible to quantify. Whether or not this system really does that is something I can't say, but they are not the only ones claiming it is possible and I have read an independent article on line somewhere attesting to it. If I can find it I'll post a link.

franklinmanklin,
To address your question as asked / implied, utilities do not bill you on individual phase currents and they do not assess penalties for imbalance. You may end up PAYING for it indirectly as I outlined above, but if that salesman said or implied you get a direct penalty, that's further evidence that he is a fool or a liar, neither of which should be suffered.

Power conditioners most commonly regulate the voltage by solid-state switching of secondary tap changers in 0.5% increments.

Just to be clear. Due to manufacturing tolerances, there is an inherent resistance/reactance imbalance in the motor itself. In specialty motors, like submersible integrated water pump/motor assemblies, this difference can be fairly high. A voltage imbalance may enhance that or even mitigate it. That is why if you have imbalanced current and voltage readings phase rotation - not switching - is the recommended first step.

 

[robbietan]

Isn't voltage balance going to be somewhat dependent on load balance? Utility can only do so much on their side, if customer has large load on only one or two phases isn't that going to draw the voltage down on those phases? If the next customer down the road has a heavy imbalance the first customer may see some effects of it.

that is correct, most of the load unbalance comes from the consumer. however, utilities still have some responsibility of balancing their customers so that they dont aggravate the unbalance already present in their customers.

 

[mivey]

that is correct, most of the load unbalance comes from the consumer. however, utilities still have some responsibility of balancing their customers so that they dont aggravate the unbalance already present in their customers.

It is done because balanced loading is the economical way to run a system. But seasonal and varying loads have always been a problem. Regulators help to some degree but there is only so much than can be done while keeping the cost of power within reason.

 

[franklinmanklin]

I posed the question regarding getting charged by each phase's current (kWH) and from what I have gained the peak usage is how the rate is set. So, if you can balance out the load it lowers the peak. They claim a return on investment in around under 3 years.