How much better are voltage optimizers compared to a traditional capacitor bank and PF correction 7

[VMMF]

My provincial government just opened 3 tenders to provide voltage optimizers for 3 schools. I've been reading a bit about them and I really don't foresee many benefits.

I consulted these links:
Short length article
Medium length article
Long article

These were the essential ideas from the articles:
• The use of motors is the largest area where voltage optimisers can make savings. It has been shown that less power is drawn on white goods like fridges and freezers, but only a few percent less. The main savings are to be had in industrial and commercial motors.
• Lighting savings can be made on magnetic ballast or incandescent lighting (because they become slightly dimmer), but there are no savings on LEDs.Tthere is a benefit in the form of longevity as lighting installations operating at the higher voltage levels may deteriorate more quickly that those operating at a lower controlled voltage level. Converting to LED will save you far more money than any small savings gained by installing a voltage optimiser.
• Heaters will consume less power using a voltage optimiser, but consequently will produce less heat and therefore no savings are achieved – so in our opinion it is easier to simply turn the thermostat down!

If voltage optimization lowers the voltage, doesn't it make something like an industrial motor slower and less effective? Won't it make something like a refrigerator or an air conditioner less effective at cooling? Won't it make your lights dimmer?
The answer is sometimes yes, sometimes no. If you supply something like a motor with more voltage than it needs, it doesn't spin any faster: it just wastes the extra energy as heat. Reduce the voltage and you reduce that wasted heat before you reduce the useful energy that turns the motor. In other words, if you run the motor at its ideal, lower voltage, you make it more efficient. The energy you save in this way is energy you're not drawing from the power supply, so it translates into a financial saving (for you) and an environmental benefit (for the planet). It's worth remembering that if you run appliances with too much voltage or current, they'll wear out significantly more quickly. Extending the lives of electrical appliances also translates into financial and environmental benefits.

I have the following questions:

1) Does a motor of lets say 100 HP depend on the presence of a voltage higher than nominal to be able to deliver 115 HP for a short time (service factor 1.15)?
2) If I limit the maximum voltage supply to a motor to the nominal value how is that better to not limiting it a putting a capacitor to compensate the PF when the motor runs?
3) Is there really a benefit on installing voltage optimizers for industrial customers compared to an automatic tap changer transformer + a multi step capacitor bank + some harmonic filters (if required)?
4) Are you familiar or have you used this voltage optimizers technology. It seems like a sales wording for me

 

[waross]

Nola again.
Google "Frank Nola", "Nola devices", "Nola NASA".
Does it work? Yes.
Is it worth it? Probably not.
A Nola device does not help with a fully loaded motor.
Beware of percentages. A percentage of a small number is an even smaller number.
Many motors, particularly larger motors, maintain their percentage efficiency down to about 50% load.
Look at it this way, if a 90% efficient motor is drawing 10 kW, the losses may be 1 kW.
The same motor at 50% load may have losses of 0.5 kW, or 5% of the motor rating.How much do you want to spend to save a part of 0.5 kW on a 10 kW motor?
Nola devices save a part of a small number when a motor is grossly oversized.
It is so much cheaper to start with a properly sized motor.
I am sure that there are niche applications for Nola devices, but they are few.
Nola devices have been around for about 35 years.
Power factor correction saves energy and reduces the cost of infrastructure.
PF correction is almost universal.
Nola devices, not so.
Nola principles are valid if not economically sound technology.
The marketing of Nola devices is often misleading and bordering on scams.
If you are evaluating Voltage optimization projected savings, don't be misled by percentages. Look at the losses in Watts and the projected savings in Watts.
Then when looking at energy costs, look at the cost per Kilo Watt hour. In addition to the invoiced charges for energy, there may be additional delivery charges and these charges may or may not be related to either kWHr or to KVAHr usage.
The case AGAINST Nola devices is economical, not technical. Economics change both with time and by region.
NASA:- Nola

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[waross]

Another point to consider:
No all losses are losses in the big picture.
Many years ago, when OPEC was curtailing and energy conservation a new topic, I took a short course on energy efficiency.
We were presented with the following example of an energy conservation project:
A school was retrofitted with with a system designed to reduce lighting costs.
The lighting in the hallways was reduced to very low levels for most of the day. The system was tied to the master time clock and the lights were all turned on just before class breaks and then off shortly after breaks.
Classrooms were fitted with sensors that measured the amount of sunlight entering the windows.
The rows of lights nearest the windows would be turned off when there was enough ambient light entering the rooms.
Unfortunately the course material did not include any firm prices.
After the presentation, there was a discussion period.
The school in question was at 53.9 degrees North latitude.
The city was fairly close to one of the largest Hydro-Electric projects in Canada.
At that time, oil heating was common.
My questions:
I understand that the lost energy is lost as heat energy. Is this correct?
I understand that electricity is quite cheap in that location. Is this correct?
I understand that the school is presently heated by furnace oil or bunker fuel. Is this correct?
I understand that most of the school year, heating of the school is required. Is this correct?
This leads me to the question:
When the savings of the new system were calculated, was the cost of heating fuel needed to replace the "Saved" energy deducted from the projected savings.

When the savings of the new system were calculated, was the cost of heating fuel needed to replace the "Saved" energy deducted from the projected savings.

This may be a question that a concerned taxpayer may ask in the present case.


Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[itsmoked]

VMMF: Chops for the clear question.

1)Does a motor of lets say 100 HP depend on the presence of a voltage higher than nominal to be able to deliver 115 HP for a short time (service factor 1.15)?

No. Nominal is just fine. The motor "takes the current it needs" for any particular load. The motor is designed to accept between +/-5% of the nominal design voltage.

2) If I limit the maximum voltage supply to a motor to the nominal value how is that better to not limiting it and putting a capacitor to compensate the PF when the motor runs?

PFC is for the power supply's benefit. Everything in the power supply's entire chain must be sized a little larger to provide the additional excitation current needed in a lower PF. However a lower PF does consume more energy and having a lower PF at a location may or may not matter to one's power cost. It depends on the local power tariff structure. Always check that before bothering with PF correction efforts. (This does not apply if distortion power factor is your facility's issue. Always do what you can to mitigate distortion PF issues)

3) Is there really a benefit on installing voltage optimizers for industrial customers compared to an automatic tap changer transformer + a multi step capacitor bank + some harmonic filters (if required)?

No. You can only know if you do a motor by motor study of a facility's equipment. You also need to consider the NOLA device's probability of adding another failure point. Having one fail will bring down a plant or machine for the time it takes to troubleshoot and repair it. Typically that might eclipse the savings of the NOLA device whose savings are generally scant as waross explained.

4) Are you familiar or have you used this voltage optimizers technology. It seems like a sales wording for me

I have not been enticed into using it. And you are correct it is sales-pitchy. Notice this statement: "It's worth remembering that if you run appliances with too much voltage or current, they'll wear out significantly more quickly." Malarkey!

Keith Cress
kcress -

http://www.flaminsystems.com

 

[VMMF]

Thank you for introducing me to the Nola concept!

I see what you mean. They were saving on baseboard heating electricity but not considering the extra oil cost that they would require for their furnace

 

[VMMF]

Are you saying that if a motor is rated with a service factor of 1.15 which makes its wingdings resistant to more current for a brief time it still will only consume the nominal FLA?

If a motor maximum voltage supply is limited, the maximum current will be limited right? Just like a star-delta starter plays with voltage to limit the motor starting current. PFC does not restrain voltage and current, it just makes them more "in phase" which saves energy losses on current absorbed by inductors on half cycle and released on the other half. Is an unloaded motor consuming less kW but the same amount of kVA that if it were loaded? In other words,assuming a motor without PFC, does unloading it affect its power factor?

 

[waross]

Back to square one on motor currents.
A motor draws reactive or magnetizing current. This is fairly constant but does increase slightly as the load increases due to the air gap distorting slightly as the load increases. This may be corrected by PF correction.
A motor also draws real current in direct proportion to the load, where the load includes running losses such as windage and friction.
There are a few other losses such as eddy currents and hysteresis which are minor and which we will ignore for now.
The real current and the reactive current do not add directly but follow the triangle model where the real current is the base, the reactive current is the altitude and the hypotenuse is the resultant current that you will see with a clamp on meter and is shown by the FLA rating.
Back to the FLA.
The motor does not necessarily draw FLA. It draws enough real current to drive the load, plus the directed additionof the magnetizing current.
What will a Nola device do?
The reduced voltage will reduce the magnetizing current under light loads.
As the load increases so does the Nola output voltage and the saving tapers down to nothing at full load.
Contrast with capacitors.
Capacitors will supply the reactive current at all load levels, including full load.
Note: The capacitors do not change the motor currents, but supply the reactive current locally so that reactive current is not drawn from the grid.
The load component of the motor current. Nola reduced voltage will reduce the losses, but there is no free lunch. The motor will have to supply the KWHrs demanded by the load and you will have to pay for those KWHrs.
Where will a school benefit?
Heating and ventilating? I am not an HVAC guy, but if your fans have more than a 2:1 turn-down ratio under different heating conditions, it may be well to look for a mechanical solution to provide a more even load on the fan motors.
Pumps? Again a mechanical design issue if the pumps are oversized.
Where does Nola work?
A escalator at a subway station may be an excellent application of a Nola device.
A large motor is running unloaded for most of the hours in a day.
During rush hours, as a subway train unloads, the motor may be pushed into it's service factor loading for a few minutes, and then drop back to almost no load, until the next train arrives.
For a school, the first step is PF correction.
The next step is to review the load profiles on the motors. Look for oversized motors. Look for mechanical means to avoid extreme load swings.
Don't be misled by percentages.
As for actual savings in Kilo-Watt-Hours, AFTER the power factor has been corrected.

You mentioned electric heating. Back to KWHrs. It takes an amount of KWHrs to offset the heat losses of a building.
Reducing the voltage just changes the on-off cycle so that the on cycle is longer until the same KWHrs are delivered and paid for.
During the heating season, reduced motor losses may be offset by longer on times of the baseboard heating, depending on the ventilating design.
This holds true for lighting reduction but is site specific for HVAC motors.
There are often savings to be had by reducing the demand charges by peak reducing.
You need an energy audit before going down this path, but a review of the power bills for the last year or two , comparing peak demand with average consumption is a good place to start.
The energy audit should not be limited to electric energy but should include an evaluation of other energy usage such as heating oil or natural gas.

Nola savings are at light loads, If a NOLA device shows savings on demand charges then you may have some seriously oversized motors.
A possible exception:
There may be a case where the change-over from heating to cooling or heating or cooling with the help of outside ambient air, where large load changes on a large motor are unavoidable.
Possible remedies to evaluate:
A part winding start motor designed to run on one winding at low loads.
Two motors belted together and energized as needed. eg: a 25 HP motor belted to a 59 HP motor will give the options of 25 HP, 50 HP, or 75 HP.
A DIY Nola system. Use an auto-transformer with one or more taps and automatic switching to match the motor voltage to the load.
Despite my skepticism of Nola Technology, the DIY Nola may actually be the most economical remedy, IN THE EVENT that it is determined that there may be a benefit from Nola Technology.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[VMMF]

So from your explanation I see the FLA rating is for the combination of load + magnetizing current (resistive + reactive) where the reactive barely changes depending on the load and the resistive changes a lot. The voltage required to move the motor is proportional to the load + magnetizing current demand.


So, the nominal voltage on the motor nameplate is required to produce the FLA. In practice if the motor is half loaded only "half" (in any case less) of the nominal voltage is required between the motor terminals. If the motor is half loaded without Nola device, full nominal voltage would be applied at motor terminals but only "half" of FLA required to the load and the rest of applied voltage contribute to losses in heat dissipation? This is were the Nola device ability to decrease the voltage adds a saving?

What a wonderful example


I would think that the consumption peak for the building would occur when the motors are at full load. In this scenario the Nola may be of little use and having a local battery bank or small diesel generator synchronized with the grid to help soften the peak energy burden may be better. Now, I'm not sure if schools pay for peak energy and would have money for these solutions. I know industries do.


Other than in motor loads, of which schools may not have too many. We agree in heating there's not much savings (things just take more time to heat) and on LED lights either (according to the articles only the life of the lights is improved). Any other use case for Nola? I think they are mostly a sales trick except for when you have a big motor used at full speed only 20% or less of time and you couldn't go with a smaller one during that 20%. Although having motors working in steps is a great suggestion for that scenario

 

[waross]

Fun with numbers:
100 kW motor. 10% loss = 10 kW losses, mostly I[sup]2[/sup]R in windings.
100 kW motor running at 25% loaded,= 25% current.
I[sup]2[/sup]R losses in windings at 25% load = 10 kW/(.25% x .25%) = 0.125% = 1.25 kW losses. even a 50% reduction is only 0.625 kW out of 100 kW.
A large reduction from 0.125% losses is still a small number.
Note: I have neglected some loss factors. The point that I am trying to make is the difference between percentages and real numbers.



Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[jraef]

I'm not going to sugar coat it. These things are scams.

The concept is that if you can reduce the voltage supplied, then there will be reduction in your electricity bill.

Their opening statement right there is absolute unadulterated bovine excrement. Everything they say after that is their pathetic attempt to justify that initial stupid statement, so regardless if any sprinkling of truisms in there, the entire premise is false from the outset and designed only to extract money from your budget.

What happens a lot, and why they can get "testimonials" (assuming SOME of them are true) is that people approve spending money on these scams, then have to "justify" that by showing savings. But of course what's really happening is that because they NEED to show that, they ALSO implement other simple common sense actions, like turning things off when not in use, raising thermostat settings in summer or lowering them in winter, cutting back on everything, which cuts back on energy use, etc. Then at the end of the year they compare the energy bills and immediately attribute it to these scam devices that they foolishly invested in.

I should know, I used to sell one and was involved in what turned out to be a scam. In my defense, I NEVER told the guy that it was going to save him energy to use them, I was selling him Soft Starters for his cooling fans and they had the Nola circuit on them. But HE (plant maintenance mgr) was chasing a big bonus from his employer for "saving energy", so he submitted the energy bill savings and claimed it was because of the Nola Energy Saver in the Soft Starters that he bought from me. That was BS, the soft starters had bypass contactors so that Nola circuit never was engaged. They saved energy because they ran the fans less. It turned out that people left them running a lot more than necessary because of the old wives' tale that "It takes more energy to restart a fan than it does to leave it running for hours longer". That has NEVER been true, but the myth exists to this day. So when he put in the Soft Starters, he told the operators that it was now OK to turn the fans off when not in use, and THAT saved the energy. But he got his $60,000 bonus and retired. A year later I was called to the carpet because an audit was not showing any real change in the OPERATING energy of any individual motor when running with the Nola circuit engaged (compared to being in Bypass). Zero difference, because the fans were always fully LOADED when they were running.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[VMMF]

Thank you so much for sharing this real life experience. I'm growing very concerned because I see there are now 5 parallel tenders to install these Nola devices on 5 different schools and my concern is that they may have previously run a pilot project on some initial school which showed improvements because they "NEED to show that to justify the expense" kind of situation.

 

[JohnMcNutt]

To echo Jraef's story. If I see a project has no technical merit, I decline to be involved in any way. Whether I see there is money involved, or not.

There was a customer of ours who also wanted some sort of "filter for dirty POCO power" installed. I respectfully declined. A colleague took on the job. a few weeks later I heard he was back out because the lights went out in the middle of the night. Something went wrong with the contraption.

Because of their lack of merit, and the scammy nature of their builders, these sorts of things are never built very well. Plus the inevitable addition of complexity into the system.

 

[VMMF]

Well, I understand that you have your reasons to decline the job. I would have explained to the customer all the things that could go wrong, i.e. added complexity and cost, little savings (depending on their facility), extra point of failure in the system, little quality of available solutions. If after understanding all this and being able to make an informed decision he still wants to proceed, he knows what he asked for

 

[BrianPetersen]

A VFD that can slow down the motor when full output speed is not needed, can give real savings. Changing the frequency is a whole different situation to an AC motor than changing the voltage supplied to it.

A ventilation blower might not have to run at full speed all the time. Fan power demand varies with the cube of the flow rate. A small reduction in flow rate gives a large reduction in power consumption.

Of course, if it is a fixed, constant flow rate but what's there delivers more air than what's needed, changing pulleys to slow the fan down a little is cheaper.

Normal HVAC controls are binary, not analog/proportional, though.

 

[BrianPetersen]

Well, I understand that you have your reasons to decline the job. I would have explained to the customer all the things that could go wrong, i.e. added complexity and cost, little savings (depending on their facility), extra point of failure in the system, little quality of available solutions. If after understanding all this and being able to make an informed decision he still wants to proceed, he knows what he asked for

... but it won't stop you from being blamed.

I don't want my name associated with unsuccessful projects. Can't always predict those, but if the warning signs are there, I'm out. "somebody else's problem"

 

[JohnMcNutt]

https://www.eng-tips.com/userinfo.cfm?member=BrianPetersen[/URL]]... but it won't stop you from being blamed.

I don't want my name associated with unsuccessful projects. Can't always predict those, but if the warning signs are there, I'm out. "somebody else's problem"

Exactly.

Jobs have a couple of purposes: to make the company money, but also to expand the prestige and experience of the company. And certainly they must never detract from the prestige of the company.

 

[waross]

https://www.townofsurfsidefl.gov/do...-ave---structural-pages.pdf?sfvrsn=18191194_3

Maybe not.While the fans may run constantly, the dampers are often on a PID controller.
Steam valves MAY be on a PID controller.
I don't remember the details but I do remember an HVAC system which used two interacting PID controllers to increase the amount of outside air during a favourable outside temperature.
However, even with PID control on the dampers, the air flow through the fan remains fairly constant.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!