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Discuss Problems Caused by 'Voltage Optimisers' in the Electrical Forum area at ElectriciansForums.net

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billm

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Hi there folks. This is my first post and I hope someone can help regarding some questions I have regarding 'voltage optimisers'.
As I understand them, they are basically transformers and reduce incoming supply voltage. What effect do they have on older equipment?
Would I be correct in thinking that anything designed for older equipment - pre1995, 240v should function correctly at voltages as low as 216v (240v less 6% - lowest supply voltage, less again 4% of 240v for max volt drop within installation). Post 1995, 230v equipment should be capable of running at 207v for the same reasons.
It is proposed that our incoming voltage is reduced to 220v. Surveys have shown that it will go as low as 217v including site volt drops due to supply variations. I am confident that the majority of equipment will be fine as it is mostly post 1995.
The problem may be some older three phase crane motors whose plates give an operating voltage range of 400-440v.
If the supply voltage, single phase,is reduced to 220, dropping to 217 occassionally - i.e. averaging 380v three phase, dropping to as low as 375v, will the motors still work? What problems am I likely have with them. Will I have to change inverter setups?
Any help anyone can give would be greatly apreciated.
Cheers, Bill.
 
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dh-ef

  • Thread Starter Thread Starter
  • #2
Voltage optimisation (i.e. controlled voltage reduction) can give useful energy savings on some sites - depending on the types of equipment on the site.

If the resultant voltage is too low for one or two items of equipment, then consider installing a step-up transformer on the circuit supplying that equipment, to boost the voltage by a few percent. The savings achieved on the rest of the equipment on the site may far more than offset the cost of this small transformer.

By the way, be careful of using fixed-ratio "voltage optimisation" equipment, as your site will be vulnerable to voltage dips on the supply from the grid. A better option may be to use a proper voltage stabiliser designed for this purpose, as this will ensure that the site voltage is maintained at the desired level.
 
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billm

  • Thread Starter Thread Starter
  • #3
Voltage optimisation (i.e. controlled voltage reduction) can give useful energy savings on some sites - depending on the types of equipment on the site.

If the resultant voltage is too low for one or two items of equipment, then consider installing a step-up transformer on the circuit supplying that equipment, to boost the voltage by a few percent. The savings achieved on the rest of the equipment on the site may far more than offset the cost of this small transformer.

By the way, be careful of using fixed-ratio "voltage optimisation" equipment, as your site will be vulnerable to voltage dips on the supply from the grid. A better option may be to use a proper voltage stabiliser designed for this purpose, as this will ensure that the site voltage is maintained at the desired level.
We have since fitted a variable voltage 'optimiser' to our site which allows us to control the in coming supply to within 1v and it is doing what we were told it would - reduce electricity consumption and save money! This unit has the added advantage of allowing us to monitor and record when maximum demand occurs, phase loading (allowed us to balance loads on phases better), phase voltages, see what our non-production consumption is and see what effects any changes made have on consumption. We can now also tune the unit down in 1v stages to see how low we can go without causing problems.
We initially went for the variable option after hearing of problems caused by the fixed ratio units - a mate fits the fixed ratio units and warned us of problems. The main one being that when you have your voltage logged it is usually only logged on one phase (easy to plug the data logger into a 13a socket than connect across a 3 phase supply), it doesn't take into consideration variations between the phase voltages on a three phase supply - in our case that can mean 3v which may not sound a lot but when these units are set to reduce to the lowest acceptable voltage and the tested voltage happens to be the highest, this can mean the other 2 phases are running below allowable limits e.g. black phase216v, grey214v, brown213v. This can cause problems.
There is also the issue of 'shock' loading equipment which has run quite happily on 240v for the last 20 years suddenly being expected to run on 220v with no wind-down period. I've heard of lighting and fire control panels failing because this. The variable unit allows the voltage to be stepped down 1v at a time giving everthing a chance to slowly get used to it.
As you can probably tell, I'm quite impressed with the unit I have.
 
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dh-ef

  • Thread Starter Thread Starter
  • #4
Bill

Thank you for the information about your installation. It would be interesting to hear how much energy you are saving.

I would also be interested to know more about the "shock" loading you refer to: not something I have come across before. What type of equipment suffers from this problem?

David
 
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billm

  • Thread Starter Thread Starter
  • #5
Hi David,
We are saving around 8% of our electricity with a voltage reduction of 7%. This is taking the voltage down from a peak of 243v per phase down to a steady 225v. There is capacity to reduce it even further but I dont want to risk it yet, the system we have reduces incoming voltage by a maximum of 20v.
I have been told to reduce the voltage gradually by both the installers of my unit and a mate who installs another make as the fixed % reduction - sudden drop - can cause lights to fail and the mate had a complete fire alarm system fail (this was an old system which may have been due to fail anyway but who knows). I haven't had any such problems with my unit and to be honest I was expecting some due to the age of some of the equipment.
Hope this information is of some use to you.
Cheers
Bill
 
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skirby

  • Thread Starter Thread Starter
  • #6
Do you think that Voltage Optimisation would have any significant benefit in a domestic installation?
I hear there are residential trials of the Vphase unit.
 
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SirKit Breaker

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  • #7
I think i will put my head back under the floorboards, sounds like rocket science to me !!!!!!
 
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skirby

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  • #8
The same science that gave us those plug-in water softening gizmos where the wires wrapped around the pipes.
 
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poppypiesdad

  • Thread Starter Thread Starter
  • #9
And the save fuel magnets on your fuel pipe?
 
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skirby

  • Thread Starter Thread Starter
  • #10
Yep. The worrying thing is that the government are backing the installation of these devices in homes.
I suppose as electricians we can make money from installing them, but it doesn't seem right to me if they don't actually reduce electric bills.
At the moment I think it's a matter of the greedy and the ignorant leading the blind.
 
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skirby

  • Thread Starter Thread Starter
  • #12
I am coming around tho the view that Voltage Optimisation in most installations would not be a bad thing. I've been keeping an eye on developments over the past few months and it seems to make sense from an investment point of view, both financial and in extending the life of most electrical equipment. In it also creates the possibility of work for electricians especially in the domestic sector. The first question most people ask is 'does it work?' and then 'how much will it cost?'. There is some more interesting info about domestic voltage optimisation and a link to Gatecrash UK Energy Project at Domestic Voltage Optimisation does it work?
I'm sure we will be hearing a lot more about this subject and eventually we electricians will become well versed in explaining the pros & cons to the general public.
 
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blakeyat48

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  • #13
hi this seems to be the hot topic for 2011 but my question is if the voltage is lowered after the design of the building has taken place. by reducing the voltage by 20 volts at supply that will have an effect on ampage being drawn on each circuit wont that effect cable size and volt drop
 
These devices seem pointless. Almost all electronic devices these days have switch mode power supplies in them, so will just draw more current if the input voltage is lower. Heating elements will not get as hot, but since you generally want to put a certain amount of energy into whatever you're heating, it'll just take longer to do the required task. This implies that you'd actually end up using more power.

The only saving might be with incandescent light bulbs, but since the intensity is not linear with voltage you see quite a noticeable difference in brightness even with just 5 or 10% drop in voltage.
 
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lish70

  • Thread Starter Thread Starter
  • #15
something to consider: if you power a 10.8kW shower at 240v this = 45Amps at 220v this = 49.09Amps. Or a 9.5kW shower at 240v = 39.58Amps at 220v = 43.18Amps
 
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