Voltage optimisation?

The Dentist · 6 May 2011

We currently have a voltage of approx 240 s/p 430 3/p in the building where I work, and the management are looking into a company who can reduce our voltage via secondary transformers in the promise to save us about 17% in running costs

We use a lot of 3p motors to run conveyor equipment, and s/p for lighting and general power ballanced over the phases, using flourescent and HID lamps, can we expect to see any benefits, or indeed problems with this reduction

Assuming our max demand remains the same, surely our Kw/hour will remain constant also, and costs will remain constant also? Will reducing the voltage simply mean that amperage will increase and nothing else? I cant seem to see the logic in this, but I'm not a technical gury so would like to hear your opinions

Heres a link to the providers http://www.marshalltufflexenergy.com/voltis/how-does-it-work/

Many thanks

holmslaw · 6 May 2011

ricicle · 6 May 2011

Snake oil.

ericmark · 6 May 2011

I had a problem with florescent lamps using far more than rated power due to over voltage. But also problems of lamps not working due to under voltage.

Unless every lamp was same type likely trying to reduce the voltage en-block will fail.

To change the fittings for HF fittings will work far better.

Heaters may reduce output but likely will run longer. Again with shrink wrap machines I have had problems with under voltage. But not really had problems with over voltage.

Items like a PC will have switch mode power supplies so will auto compensate so will draw same power before and after.

Older equipment however may start producing a mains hum or fail completely.

Next time the supply authority change a transformer you may find voltage reduced anyway so then double reduction.

I will say using the auto transformer on lights alone may save money where florescent lighting is used. But using HF fittings would save more money. Plus remove the flicker which with some people produces head aches.

JohnW2 · 6 May 2011

The Dentist said:
We use a lot of 3p motors to run conveyor equipment, and s/p for lighting and general power ballanced over the phases, using flourescent and HID lamps, can we expect to see any benefits, or indeed problems with this reduction
Assuming our max demand remains the same, surely our Kw/hour will remain constant also, and costs will remain constant also? Will reducing the voltage simply mean that amperage will increase and nothing else? I cant seem to see the logic in this, but I'm not a technical gury so would like to hear your opinions

For 'passive' loads (primarily lighting and heating which isn't thermostatically controlled) reducing voltage will, indeed, result in reduction in current and therefore reduction in power consumption - but only because you will be getting less light or heat. You could acgieve the same saving by having less lights, lower power lights, using heating for less time or turning down the thermostats on heating devices.

For most other loads, there will be no saving. Motors, for example, need to produce a certain amount of mechanical power to do the job in hand, and that requires a corresponding certain amount of electrical power. If the voltage is reduced, as you say, the current will simply increase to bring the power back to where it needs to be. Thermostatically-controlled heating appliances will simply turn themselves on for longer (or turn themselves 'up' if that is an option) so as to achieve the desired heat output. Much electronic equipment uses switch mode power supplies, which will draw essentially the same amount of power regardless of supply voltage.

I wouldn't actually call this 'snake oil' (since there are far better examples of that product around!), but it sounds like a very expensive way of reducing the amount of light and heat.

Kind Regards, John.

bernardgreen · 6 May 2011

Voltis and Ohm’s Law

Voltage optimisation can be explained using Ohm’s Law on the basis that:
Power = Voltage2 / Resistance

Only problem with that is that Ohms law using resistance is only valid for pure resistive loads and only filament lamps and heating elements are close to being pure resistive. ( their resistance increases with temperature ).

Some motors running on reduced voltage may actually take more power than at nominal voltage as power taken is affected by speed of rotation and the back EMF generated in the motor that opposes the supply voltage to reduce the effective voltage on the windings..

ricicle · 6 May 2011

You will also have to check motor manufacturers data as in certain circumstances reduced voltage can cause rotor overheating in induction motors.

JohnW2 · 6 May 2011

ricicle said:
You will also have to check motor manufacturers data as in certain circumstances reduced voltage can cause rotor overheating in induction motors.

My understanding is that these expensive devices which are heading in the direction of snake oil are designed not to reduce voltage below the regulated limits of the supply - so, at least theoretically, they should not be able to create a situation any worse than the worst-case permitted supply voltage situation.

Kind Regards, John.

ricicle · 6 May 2011

JohnW2 said:
ricicle said:

You will also have to check motor manufacturers data as in certain circumstances reduced voltage can cause rotor overheating in induction motors.

Click to expand...

My understanding is that these expensive devices which are heading in the direction of snake oil are designed not to reduce voltage below the regulated limits of the supply - so, at least theoretically, they should not be able to create a situation any worse than the worst-case permitted supply voltage situation.

Kind Regards, John.

Unless the reduced voltage is output at the intake, and on a large site the drop becomes significant to motors further away from there as the original design calcs are no longer relevant......?

JohnW2 · 6 May 2011

ricicle said:
Unless the reduced voltage is output at the intake, and on a large site the drop becomes significant to motors further away from there as the original design calcs are no longer relevant......?

The initial design surely should have been on the basis of the minimum pemitted voltage at the supply intake. If not, the installation would be at risk of malfunction even in the absence of one of these 'meddling machines'?

Kind Regards, John

ebee · 19 Jan 2017

There are a few cases where volt optim is a good thing. But only a few and very rarely in domestics.

Gen they can be thought of as "snake oil"

ban-all-sheds · 19 Jan 2017

I'm sure that everybody found a repetition of what had been said 6 years ago very useful.

ebee · 19 Jan 2017

I have not been on for ages therefore two reasons for my post.

One to see if good old Ban All Sheds is still lurking about.
Two , newcommers might not have read it

ban-all-sheds · 19 Jan 2017

I wonder who will get fed up first with you going back over 57,000+ old topics and bumping them in case newcomers might not have read them?

You, or the rest of us?

ebee · 19 Jan 2017

Nope i have not time for 57000 + threads Ban, just an odd one is enough

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Voltage optimisation?

holmslaw

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