Voltage optimisation technology? any experience? thoughts?

[Smudge]

we had a site visit the other week by a sales rep and an engineer of a company wanting to sell us a 'voltage optimisation unit' for the factory. They have today sent me through a proposal. They have contacted our electrical supplier, and obtained our site voltage profile for the last year. What they propose to do, is to instal this unit which will reduce our voltage from 253V-239V, down to 220V minimum. Their proposal is all in single phase terms, and our site is mainly made up of 3 phase induction motors, so i have asked them the to re-do the the proposal in more relevent terms to us.

My question...

I can understand their sales pitch of lower stable voltage, less cost on utility bill (they guarantee a saving of 9.2% per annum), but i don't know that much more about it. Has anyone else adapted any such method, or had any experience in this sort of thing?

We are not considering this with any great intent (yet) as my worry is the effect of lowering the voltage too much for some of our site to function, a problem that realistically wouldn't come to light until commisioning. That alone is putting me off as our plant has areas which are VERY old machinery.

thanks for reading my ramblings...

 

[Engineer54]

9.2% Doesn't sound too much of an improvement to me, not when you consider what these companies are asking for they're box of tricks. I suppose the deciding factor would come down to pay back time, and what else you could plough that money into, as too what constitutes value for money!!

Go on, give us a ball park figure of what this system will cost, to give your company a 9.2% annual power saving saving??

 

[Brightspark2]

Dont bother...

Weve removed them on sites as they weren't saving any money, just costing money to the company. They didnt even want there units back. It caused problems on the site too, mainly discharge lighting with very premature lamp failure rate and only 1 lamp manufacturer of the few we typed worked the rest just wouldnt ignite.

Seemed to be full of false promises!...

 

[Knobhead]

Give me you’re companies address, I’ve got two cases of snake oil to shift.

220V? Despite the IET this country is on 433/250V.

You drop the voltage and wait for the aftermath! I tried it on an 80MVA 33/11KV supply. I got my arse kicked! Soon cranked it back up again!

 

[trev]

I'm with Tony on this, apart from my 50% holding in his snake oil business I also have a sideline in smoke and mirrors.

 

[Knobhead]

Power in = power out with losses.

1KW @ 220V = 4.54A
1KW @ 230V = 4.34A
1KW @ 240V = 4.16A
1KW @ 250V = 4.00A

No mater which way you look at it 1KW = 1KW, with the box of frogs + losses.

 

[brookster]

Increasing the power factor 'might' save you some cash cutting down on reactive losses, don't get it myself with voltage optimization.

 

[Knobhead]

In this country voltage regulation is mainly done at the 33/11KV level with On Load Tap Changers (OLTC).
So far I’ve worked on 180MVA of them.

Great fun when the engineering manager asks you to do voltage optimisation trials on a 80MVA set up. The accountant asked him to try it, he shifted it in my direction.

The four 20MVA transformers would normally run in “independent automatic” voltage regulation mode (they work independently of each other). I switched No.1 transformer to “manual master” the other three to “slave” voltage regulation modes. (What the master says the others follow). If ever anyone has heard an OLTC working it sounds like the transformer is being violently ill, it makes a horrible growling noise. Four of them changing at the same time is frightening!

I had the charge hand fitter in one of the local distribution substations reading out the LV voltage to me over the radio.
We set off with 433/250V on the LV.
Took it down to 415/240V, got a few shouts from production about lights failing.
Down to 400/230V, the sh!t hit the fan! Literally!
The two 2000HP exhaust fans tripped out, if that happens the plant goes in to emergency shut down. The vent valves then tripped! 18 explosion doors blew out!

I put the transformers back in to “independent auto” and went to help the fitters putting things back together.

Monday morning I had a copy of the 15[SUP]th[/SUP] shoved down the back of my pants for the arse kicking party! Didn’t need it, the accountant got kicked instead.

This is an OLTC

 

[Darkwood]

Voltage Optimises - sales people ....enough said!!

If the did what they claim they did... we would all be fitting them as routine on a board change as they pay for themselves dont they :mickey:

 

[amo]

Voltage Optimises - sales people ....enough said!!

If the did what they claim they did... we would all be fitting them as routine on a board change as they pay for themselves dont they :mickey:

well said. most people cant fit them properly either. they whack there tails straight in and expect huge savings and this just is not the case at all. best do the research first, not worth it IMO at all.

 

[Brightspark2]

In this country voltage regulation is mainly done at the 33/11KV level with On Load Tap Changers (OLTC).
So far I’ve worked on 180MVA of them.

Great fun when the engineering manager asks you to do voltage optimisation trials on a 80MVA set up. The accountant asked him to try it, he shifted it in my direction.

The four 20MVA transformers would normally run in “independent automatic” voltage regulation mode (they work independently of each other). I switched No.1 transformer to “manual master” the other three to “slave” voltage regulation modes. (What the master says the others follow). If ever anyone has heard an OLTC working it sounds like the transformer is being violently ill, it makes a horrible growling noise. Four of them changing at the same time is frightening!

I had the charge hand fitter in one of the local distribution substations reading out the LV voltage to me over the radio.
We set off with 433/250V on the LV.
Took it down to 415/240V, got a few shouts from production about lights failing.
Down to 400/230V, the sh!t hit the fan! Literally!
The two 2000HP exhaust fans tripped out, if that happens the plant goes in to emergency shut down. The vent valves then tripped! 18 explosion doors blew out!

I put the transformers back in to “independent auto” and went to help the fitters putting things back together.

Monday morning I had a copy of the 15[SUP]th[/SUP] shoved down the back of my pants for the arse kicking party! Didn’t need it, the accountant got kicked instead.

This is an OLTC

Always an interesting reply tony...





well nearly always lol...

 

[Smudge]

9.2% Doesn't sound too much of an improvement to me, not when you consider what these companies are asking for they're box of tricks. I suppose the deciding factor would come down to pay back time, and what else you could plough that money into, as too what constitutes value for money!!

Go on, give us a ball park figure of what this system will cost, to give your company a 9.2% annual power saving saving??

around 65 grand for the kit, 9.2% is around 25grand a year to us.

I was (still am) very sceptical about it all, but the idea was sold to the company directors who automatically see the £ savings and think its the best thing since wonder bra (another bloody smoke and mirrors trick).

I've raised a few questions with them, and they have not been able to answer, again because they are salesmen.the joys.

Thanks to all for responding.

 

[Knobhead]

Do you have your own dedicated transformers?

If you do, try dropping the tap changer to -2.5% and see what happens. Remember this can only be done with the transformer isolated!

 

[Darkwood]

around 65 grand for the kit, 9.2% is around 25grand a year to us.

I was (still am) very sceptical about it all, but the idea was sold to the company directors who automatically see the £ savings and think its the best thing since wonder bra (another bloody smoke and mirrors trick).

I've raised a few questions with them, and they have not been able to answer, again because they are salesmen. My job is now to try talk the directors out of it, or dust down the overtime callout boots for many a breakdown.

the joys.

Thanks to all for responding.

Tell them to put all their claims in written form signed and agree to the work.... then have a clause put in that payment will be met when the savings in Electricity has been realised...i.e. after the first year, if there claims are not realised then they system will be removed at their cost and no payments will be owed.

Lets see how confident they are when they knowing that the sales pitch they make will have to be accurate and not loose speculation .... i would scrutinise any agreements they draft up too for get out clauses or loosely based predictions.

Also explain any maintenance costs arising from the lower voltage will need factoring into there claims too.

Ive a feeling they won't be so forthcoming after this and the cracks in there claims will show, at the end of the day they are sales rep's not Electrical design Engineers/Technicians ..... i know where id be taking my advice from.

 

[UNG]

If it looks too good to be true then it is too good to be true

Too many promises with no substance to back them up is my opinion of these things unfortunately those money orientated people (accountants) look at the £'s to be saved without any engineering knowledge and don't see the hidden cost of repairing the equipment that fails until engineering are asked to justify there higher spend

 

[Smudge]

I'm not siding with the claims, or 100% against them, just looking for a decent debate on it. Their gaurantee was if the target saving was not met, then they would give us the cash difference on the FIRST year. There would have to be a lot more room for negotiation on that for starters.


playing devils advocate here...but here is an extract from the reply email i just got.


Hi Martin,

I have included some info on motors and a couple of other pdf’s that you may find interesting.

3phase is no different than single phase ... the principles are exactly the same.

For motors the key points are as follows
· We take the motor to the voltage at which it was designed to operate
· Lightly loaded motors can off significant savings
· VSD driven motors can still yield significant savings ... especially if the inverter frequency is >45Hz and the motor itself is lightly loaded
· The speed of a motor is NOT compromised AS LONG AS the voltage is not taken below it’s designed level
· Torque is not reduced ...
· IF a motor was taken to way below its designed operating voltage e.g. 209V ... then slip could increase significantly = reduced speed.
· Reducing losses in a motor should in no way be confused with the task the motor has to perform. E.g. an 11kW motor running DOL, supplied at 415Vand driving a pump to move water from A to B might reasonably consume 7kW. Reducing the voltage to the motor to 380V might reduce the motor consumption to 6kW ... but it will drive the pump at the same speed ... and water will still be pumped from A to be exactly as before.

Hope that helps!?

 

[Smudge]

Do you have your own dedicated transformers?

If you do, try dropping the tap changer to -2.5% and see what happens. Remember this can only be done with the transformer isolated!

We don't own the transformer, Scottish Power do. I find all this quite interesting, and obviously 'in theory' it sounds a great deal, but it's good hearing others experiences.

 

[UNG]

I'm not siding with the claims, or 100% against them, just looking for a decent debate on it.

If you do a search of this forum this subject has been debated numerous times before

Their gaurantee was if the target saving was not met, then they would give us the cash difference on the FIRST year. There would have to be a lot more room for negotiation on that for starters.

So your company is not going to change it's electricity usage year on year not sure how you are going to prove you have not made the savings or they can prove you have so the guarantee leaves it a bit open just because the bills may come down you may not have been using the equipment as much as you did the previous year

There has to my knowledge been no like for like, before and after trials done with these units that show beyond reasonable doubt that they deliver what they claim

 

[Knobhead]

Talk to SP, ask them if they’ll drop the supply voltage on one transformer. They’ll charge you, but it will be cheaper than buying the box of snake oil.

If it works out, leave it at the lower setting and you’ve saved a fortune in capital expense.


Trev! Where do I shift these cases of snake oil?

 

[trev]

There's some VO units on ebay for about £130 so we could try there Tony.