How to Reduce Energy Consumption (Motors)

Turn it off, when not in use or vary the speed according to load or correct volt and current lag.

is there a way to know automatically when a motor is not used and then shut down, or should it always be done manually ?

and how can you clarify more the idea of volt and current correction ?

The simplest method to know with certainty how long a motor is actually run is to wire a mechanical clock in parallel with the motor and start the day knowing what the clock face says. Certainly the voltage and frequency of the clock mechanism must match the motor but it is the simplest method.

As for power correction you must have a method to measure the power factor first. I have seen more than once a salesman push a VFD with power correction on a constant speed motor that probably operated with a better than 0.8 power factor all the time. Most of the great power factor savings happen when a motor should be OFF instead of running with no mechanical load.

This question does not bode well for your future. The best enlightenment comes from within.

Asking others to do your research will not help you get a job.

Read some of these:

• General Purpose vs Inverter Duty - Motors from ...
  
• [PDF]Soft starter or variable frequency drive? - Eaton..
• Mating New Variable Frequency Drives to Existing Motors ......
• What is a Variable Frequency Drive? - VFDs.com
  
• [PDF]Why Use Variable Frequency Drive? - Paddock Pool and ...
  
• VFDs Can Control Multiple Motors - Automation.com

Hi,

first, thank you for proposing something i can read about the topic.

And as for asking others, i thought i was just asking for some guidance, not for others to do all the work, don't you agree ?

Thank you very much again.

thank you so much for the help, i'll look into the graphs when available and try to come up with better ways to control motors when needed.

To add to this, when you study the graph of a motor w.r.t. speed on X axes and torque,%load, Power factor, efficiency- on Y axes, you find a peak at particular speed. Here you have one constant voltage and frequency. Repeat this graphs with varying V and Hz. Which may be possible to vary at particular site and for the application under consideration. You get the machine data for load cycle w.r.t. Time. Or duty cycle S1 [continuous rated], S2 , S3 .... You can arrive at what supply cycle is needed for the application. This may vary with the case under study.

Torque versus speed graph from negative syncronus[ generator mode] speed to positive sync. speed, center zero. Gives almost mirror image from center. Now this graph peaks can be shifted with the use of variable resistance of rotor ultimately reactance. In induction motor ratio of resistance and reactance plays a role which also can be manipulated to achieve peaks at desired rpm or load ultimately, also V & Hz can be varied at will with desired results.

One more thing, power factor improvement by means of capacitors or bank can be vital with latest available technology.

Is your project to reduce the amount of energy consumed, or reduce the overall yearly expense of the energy consumed?

it's to reduce the overall yearly expense of the energy consumed ? but is there a difference between these two ?

switch everything to 480 3 phase

i'm sorry but this is too vague to understand, at least for me, because i can't see why everything should be switched to 480 3 ph ?

in what way will that benefit us and help reducing the amount of energy consumed ?

thank you for clearing your idea up, and as i was informed before, all the motors used are supplied with 400V, so it seemed they've already thought about that.

Motor rating higher than 15KW usually goes 3 phase, lower than that is single phase. It's not an option, it is what is economically available on the market.

Do you ever put out anything other than total BullMierd answers? That previous one, and the one before is just crap! Stop intentionally misleading people, although I have no idea who would actually follow your advice!

Does the energy provider have a rate schedule that includes reduced price for off-peak demand energy use?

If yes, are there machines that can run during these off-peak hours?

http://en.wikipedia.org/wiki/Peak-load_pricing

the factory where i'm doing my internship, doesn't rely all the time on an energy provider, because during the period in which it starts producing, they use their own turbo generators (they have 3). But for now they are connected to the energy provider, and i haven't asked if their provider does offer a reduced price for off-peak demand energy use, but supposedly there were a rate schedule that includes a reduced price for off-peak, are you suggesting that it may be in their benefit to operate their machines in those periods so that they would be less charged for energy consumption ?

Yes.

Much like a person going to the movie theater. At peak hours, say 7:00 PM on a Friday, the seats are $10 dollars each. But you can see the same film for $5 dollars if you go to the theater at 2:15 PM on Tuesday, an off-peak time.

There are many arrows in the energy dollar saving quiver. There are a number of good suggestions regarding drives, motor jogging, etc. The best chance to hit the bullseye of lowering your energy cost is to shoot many arrows. That is to say, there are a number of things that probably can be done to reduce the monthly energy bill a little bit; if you do several of these things, a greater reduction should be realized.

This goes out the window when they are using their turbine. Doesn't matter... unless the turbines use nat. gas or the like and they can negotiate an off-peak deal with the gas supplier.

This goes out the window when they are using their turbine. Doesn't matter... unless the turbines...

you are right, it just hit me in the begining when you asked me abbout their energy supplier, and i asked myself why would they need to reduce their energy consumption if they're using their own 3 turbo generators as i've been told ?

i mean if you're not trying to reduce costs, why would one want to reduce the amount of energy that his machines are consuming ?

"you are right, it just hit me in the begining when you asked me abbout their energy supplier..."

That is called an epiphany. Pleasant feeling, isn't it?

Energy is cost. Energy is cost. Energy is cost. OOOOOOOOOOOOOOOmmmmmmmmmmm!

Meditate upon that grasshopper!

"it's to reduce the overall yearly expense of the energy consumed ? but is there a difference between these two?"

Yes there is.

Depending on the tariff that you are operating under.

If it is time of use tariff, then reducing the operation of some of the equipment during peak times will save costs, this will depend on whether you can get by without the equipment at that time.

If it is maximum demand tariff, then staggering the operation of equipment to reduce the overall maximum demand will save costs. This method can be very beneficial as supply authorities generally penalise you very heavily for going over the limit.

An example of this would be where a number of air conditioners are running, and you regularly interrupt compressor operation of alternate units for a few minutes at a time but leave the evap fan running. No one is aware that their unit is not cooling/heating for the short time that it is off, but the overall cost benefits can be huge if you keep that maximum demand down. There are a number of wireless control units on the market now that can do this on a large scale with minimal changes to the wiring.

Another example would be water heating the smart control of which can cut costs on both the above tariffs.

open and close the fridge door real fast and make sure the light goes off

Thank you for help, that's the same method i had in mind, i will try and work according to it.

you see i'm just at the starting point of this project, so i'm asking so that i can have a clear idea on what way should i take moving forward in this task. i will, though, gather those details as fast as i can, and i will provide you with all the information you asked for. However, i can assure you that your questions are answers for me, because now i know what's the first thing to do.

So, thank you for the help.

get one of these and a clipboard, you'll look like you actually know what you're doing

http://www.reed-direct.ca/product/reed-instruments-dw-6060-watt-meter?gclid=CKXljPSNy8MCFQ0bgQodnVwALw

make sure none of the belts are slipping

Is that how they reverse the motion.

Yes, it's no joke! I remember when I was a kid seeing stationary threshing drums driven from a pulley on a tractor (usually a Fordson Major) where the belt was twisted as shown to get the right direction.

There were other reasons for the practice.

It assisted a long belt to stay on the coned pulleys, especially in high wind.

It stops the belt slapping in the middle.

It increases the contact area particularly on the small pulley on short belts.

The belt can be assembled with a half twist or simply given a double twist to give even wear on both sides. In those instances, direction is not reversed.

Yes, but you would fit the belt like that if and only if you want to reverse rotation. What do you mean by coned pullers? Both saddle- and barrel-shape are roughly conical in parts. To keep the belt on pulleys are usually barrel-shaped, seems counter-intuitive (it does to me anyway) but it works. Giving it a half twist to form a Möbius strip is something else, and evens out wear on both sides of the belt. I believe somebody patented the idea (but not Herr Möbius)!

Steam traction engines were able to run in either direction simply by shifting the link reverse or other reversing methods that were employed. This altered the valving with relation to piston position and was the only way they were able to go forward or backward - there was no gearbox as such. So there was no need to twist the belt to achieve rotational change unless there were multiple devices with differing rotations running off the same engine.

The picture that started this conversation is of a steam traction engine driving one thresher only, so rotational direction is not the issue there.

Coned pulley? My senior's moment.. I intended to say crowned pulley which is what your barrel one is properly called.

The crowned pulley works for two reasons -

1. Flat belts will always run towards their first contact point, therefore both sides will attempt to get to the highest point of the pulley, which is the centre, and so it tracks in that spot.

2. The wider section of the pulley (the centre) causes the belt to be tighter at that point, and therefore the belt is slightly formed over the crown and stays there due to tension. The crown is generally only in the order of 1/16" or so for a normal pulley, and normally only the driving pulley is crowned as is evidenced in that photo by the flanges on the driven pulley.

The twist assists tracking by keeping the belt forming tension more firmly on the driving pulley.

OK thanks for the explanation. I was thinking of the Fordson Major. I know steam engines can reverse, but I wasn't aware of advantages of a twisted belt, so you would run the engine the "wrong" way, and twist the belt.

Good one Fred

Thanks for the memories.

... you were probably given clear assignments previously.

yes, i'm to come up with a plan to reduce the amount of energy consumed by 1MW or 1.5MW.

...install "time of operation" clocks ...

how can a "time of operation" clock be installed ? or should i just see if there is a supervision room from which motors are monitored ?

...methodically find out if a power savings can be found not to reduce the cost by a certain amount.

well, as i said before, i have to reduce the energy consumption ( of course the costs are going to be reduced accordingly, but as i mentionned before during the period when they are producing, they use their own turbo generators, so maybe they don't have to worry much about the cost since they are disconnected from their energy provider in that time )

...Depending on the motors task this may be a mandatory way to operate. It maybe a way to save power without any changes in hardware, too.

are you suggesting here that we might want to think about avoiding the ON-OFF cycles and keep the motor operating or what exactly ? can you please clarify more because i didn't get this last point very well ?

As far as running a motor constantly, yes you might save energy by changing how a process is performed and keeping a motor running. You might use more power by keeping a motor running. I do not know which of those two scenarios will be correct in every situation. That is your task to discover. My point there is that you may find it more effective to examine how these motors are used than to try making the motors more efficient.

If you have an electrical engineer at your establishment (or if you are that), then it should be no problem to put hour meters on all the control cabinets at the MCC. If the systems are operated by a PLC or set of PLC's, then it should be not a huge issue to add logic to produce a timed counter for where the motor is activated (energized). For the larger motors, there may even be voltage, current, and phase angle instruments on these to tell you everything you need to know about electric power consumption.

By the way, badly aligned motors to the driven equipment waste tremendous amounts of energy, heat up more, and result in various types of equipment failure due to excessive vibration. I don't remember anyone bringing that into the conversation.

thank you for mentioning that, that was very helpful of you.

You imply an important point that our student should understand for a proper analysis. A motor that successfully runs a misaligned machine will be a more efficiently running motor than the identical motor in a perfectly aligned machine. More of the electric power consumed goes into some mechanical activity. That activity maybe doing the undesirable act of damaging the machine but the machine is still running.

Some other considerations to investigate.

1. Does the electricity supplier base their price rates on peek demand? Reducing this peek demand can put you at a lower KWH rate.
2. Are you paying a penalty for low power factor? This can be corrected.
3. The first place to investigate is the factory's compressed air system. Air compressors are huge energy hogs, and correcting inefficiencies in the system such as air leaks, excessive delivery pressures, improperly sized compressors, rapid compressor cycling, undersized air receivers, etc. can have a significant effect on the overall energy consumption.

for those that are not familiar you can save quite a bit on electricity in larger commercial situation by load shifting your cooling/AC needs. the cap X isn't free but they really do work...I've been to the place that sells themhttp://www.ice-energy.com/technology/ice-bear-energy-storage-system/ basically you make ice all night when your rates are cheapest, then melt during working hours using much of your existing equipmenthttp://www.ice-energy.com/technology/ice-bear-energy-storage-system/

Is there any waste streams in the plant? Sometimes you can use waste heat or solid waste for energy production....I would check for any incentive programs from government or local green organizations that might have suggestions of alternative energy supplies that might be suitable....I would also establish a relationship with your power provider to see what suggestions they might offer...Reducing energy usage of motors might include redesigning the production or process line to a more efficient way of doing things...The first thing to do is measure the amount of energy being used, and the cost of it in real time....You must have an accurate reading of how much you are spending to compare with any competing ideas and/or strategies...

Don't just stop at the motors. What about lighting. If that's on, in an area that does not need to be, that's a real simple fix. More expensive is the type and efficiency of the lighting. But changing that can have a short payback.

Also are there hidden loads of personal coffee pots and refrigerators.

As Fredski pointed at HVAC, don't over look improvements there.

Look at every consumer of the input power. But as your an intern, ask your manager about looking beyond motors. Do it in a way that they will be impressed by your vision. That your taking the task and running with it.

One of the largest waste of energy is from motors that are over sized. Check the motor load to verify it is the correct size. You can install VF drives to compensate for this problem or change the motor.

Use high efficiency motors.

Check the ROI.

Reply to response #28

That's a lot of power reduction for a goal. Is this for a city or a really big plant? Or maybe several plants?

It sounds like it could be your job for the rest of your life! How big are the typical motors?

Typically consumption is in terms of VA hours or in your case MVAH (Mega Volt Amp Hours). It's not just the size of the load, it's about how long it is being used. There are many possibilities and some bad ideas out there as well. Your utility billing figures into the consumption question. You need to understand how they calculate the charges.

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Dear Mr. rayhud,

1. Use VFD for the motors.

2. Load the motor to optimum level, for which you ave to size the motor properly.

3. Check the Power Factor and ensure it is in the range of 0.92 to 0.95

4. Use Energy Efficiency Motor(s).

5. Maintain Input Parameters with in the permissible limits.

6. Ambient Temperature to be precisely taken care for the motor. A motor selected for lesser ambient temperature should not be put in to use at higher Ambient Temp.

Sl. No. 1 and 4 will be costly.

DHAYANANDHAN.S

Dear Mr.DHAYANANDHAN

thank you so much for the tips.

about No.2 , how can we know that a motor is not used in its optimum level ? in other words, what's going to indicate that a motor is oversized for the load it's driving ?

A kinematic analysis works.

Your project reminds me of how methodical data collection can optimize operating time. A periodic checking of a running mechanical machine with a contact microphone with a fast fourier analysis of the "sounds" heard in the structure can identify a failing or misaligned part before a catastrophic failure occurs. The key here is to record and compare present analysis with past analysis. Also the point where the contact microphone gets placed must be consistent. Adding microphones to the machine or marking the places to mount the microphone for consistent data collection is important.

This is outside but related to your actual assignment of trying to optimize the power consumption.

I was tasked to do this type of audit once and kinda tripped across a different cost savings scheme.

Do you know what one of the most expensive commodities in a manufacturing environment is?? Compressed air. yeah I was a doubting Thomas until I did the calculations.

Just by eliminating air leaks and wasteful use of compressed air can and will save a tremendous amount of monies for your employer, throw this out there and see if you can gather some brownie points.

Ding! Ding! Ding! Ding! Ding! Folks we have a winner! Wrench Twirler is spot on with that blow to energy wastage the world over. Most of the hot compressed air leaks can and will be found near Washington, D.C.!

Yes, there is much to say about compressed air systems sucking up hyge parasitic loads, by their constant cycling, or just plain never cycling off on top pressure. Usually a decibel meter is a first order leak finder. The try all the little pressure regulators on air controlled valve switch boxes. Busted air switches will also blow off a lot of air. Bad pipe and tubing fit up practices will account for probably about 5-10% of wasted air, put that off to last.

First study motor design and identify the components of a motor that consume power to produce work. (The higher understanding of motor design and function you achieve, the higher your chance of being successful at finding a viable improvement in motor efficiency.)

Identify the components and manufacturing methods that create power losses within the motor which are converted to/given up as heat. (core losses, hysteresis, insulation characteristics, poor cooling design, poor bearing design/selection?)

Investigate which improvements can be made to which motor components that can effectively reduce power losses and power consumption waste. (better materials, higher permeability stator & rotor laminations, smaller or larger shorting bars or rotor rings, better conduction, better/improved cooling, variable frequency application, location of application peak torque requirement in the motor RPM, ?)

Keep in mind the cost effectiveness of any changes and remember that cost savings add up over the long haul.

Be sure to keep you findings well documented and include the reasoning for reference and justification of your thesis.

Obtain and read current as well as pending motor efficiency improvements in motor design from various manufacturers. (brochures, sales information, etc.)

Good luck!

Good points. However, I think your perspective is off in this case. This student is not tasked to redesign the electric motors themselves to improve efficiency. This student is tasked to improve the electric motor usage at this company. Knowing that most new motors are more efficient than old motors is a sufficient guide for now. Knowing that the Spacely Sprocket motor gets a higher efficiency from reduced eddy currents in the core while the Acme motor gets an improvement from rare earths in the core allowing for a higher B field is immaterial.Mechanical energy not going directly into producing product is the most likely inefficiency. Pneumatic line air leaks, constant spinning up and down of flywheels, moving heavy material to light material for little reason are the type of concepts to explore.