Problems Caused by 'Voltage Optimisers'

[billm]

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.

 

[Dunc]

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

Erm, wrong. If a shower is rated at 10.8kW at 240V then the load will be 45A as you state. However, you then have to work out the resistance of the element by applying ohms law (240V/45A=5.33ohms). Now the thing to remember is that resistance, regardless of the applied voltage, will never change. So, if you then apply a lower voltage to that resistance (220V/5.33ohms=41.28A) the current drawn will come down. It's pure physics and if you need further proof read this link (specifically page 3) which shows you the wattage of a Mira Sport shower decreases when run at a lower voltage, the same as all other showers.

 

[lish70]

Hmmm, I'm just learning but I thought that 10.8kW @ 240v = 5.333ohms whereas 220v would = 4.481ohms? Where am I going wrong? Help please

 

[Engineer54]

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

These units are not water softeners, by any stretch of the imagination, ....but they DO actually work in reducing limescale. I have 2 such units here, one in my main house where we live and another in our rental property. Here in Cyprus we have terrible water quality, before fitting these units the taps, shower heads got caked regularly with limescale, the kettle an coffee maker, scaled up to a point they needed descaling every couple of weeks or so. Since fitting them, haven't had any problems with limescale build up anywhere. It's been about 6 years now and still working just fine!!


Can't speak for any other manufacturers units, but the the ones i purchased work, and work well!!!

 

[Dunc]

Hmmm, I'm just learning but I thought that 10.8kW @ 240v = 5.333ohms whereas 220v would = 4.481ohms? Where am I going wrong? Help please

But the thing your missing is that a heating element has a set resistance. In it's most simple form all a heating element is is a length of wire of a high resistance. The only way that resistance will change is if you make the wire longer or shorter not by applying a different voltage to it. Hope that makes sense.

 

[lish70]

Of course, makes perfect sense. Should have had that early night I promised myself. For some crazy reason I was thinking that a 10.8kW showewr would still draw that amount regardless of the voltage. Cheers Dunc.