3 phase and single phase wiring

Photo is in my album as not sure how to add on to the post

<linked to photo in album - Neil>

Edited By Neil Wyatt on 13/05/2014 18:20:21

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Yes and no. - Well sort of ish.!

What you have is (probably) a duel voltage motor. But it's a 3 phase duel voltage motor.

To run it off a 240 single phase supply you would need to incorporate an inverter or a transverter. So you would need to purchase one of those.

Not what you wanted to hear. - Sorry.

Edit :- Just looked at the photograph. It is what I thought.

Nick

Edited By Nick_G on 13/05/2014 13:03:05

In a word, no. It's a three phase motor that can be run in star or delta.

Andrew

PS: Beaten to it!

Edited By Andrew Johnston on 13/05/2014 13:02:25

Mike it is as said a 3 phase motor which will run on 415v when connected in start and 240v (3 phase) when connected in delta. You could purchase an inverter to run the motor on 240v and you would then have the benefits that a inverter brings.

But this is a good thing 'cos everyone want the variable speed facility of the inverter/motor combination but can't always afford it and you have got only half the cost thanks to grandad - toast him in the pub tonight for his forethought.

Note on Supply Voltage Level:

"For many years the supply voltage for single-phase supplies in the UK has been 240V +/- 6%, giving a possible spread of voltage from 226V to 254 V. For three-phase supplies the voltage was 415 V +/- 6%, the spread being from 390 V to 440V. Most continental voltage levels have been 220/380V.

In 1988 an agreement was reached that voltage levels across Europe should be unified at 230V single phase and 400V three-phase with effect from January 1st, 1995. In both cases the tolerance levels have become -6% to +10%, giving a single-phase voltage spread of 216 V to 253 V, with three-phase values between 376V and 440 V. It is proposed that on January 1st, 2003 the tolerance levels will be widened to +/- 10%.

Since the present supply voltages in the UK lie within the acceptable spread of values, Supply Companies are not intending to reduce their voltages in the near future. This is hardly surprising, because such action would immediately reduce the energy used by consumers (and the income of the Companies) by more than 8%.

In view of the fact that there will be no change to the actual voltage applied to installations, it has been decided not to make changes to the calculations in this book. All are based on the 240/415V supply voltages which have applied for many years and will continue so to do.

In due course, it is to be expected that manufacturers will supply appliances rated at 230 V for use in the UK. When they do so, there will be problems. A 230 V linear appliance used on a 240 V supply will take 4.3% more current and will consume almost 9% more energy. A 230 V rated 3 kW immersion heater, for example, will actually provide almost 3.27kw when fed at 240 V. This means that the water will heat a little more quickly and that there is unlikely to be a serious problem other than that the life of the heater may be reduced, the level of reduction being difficult to quantify.

Life reduction is easier to specify in the case of filament lamps. A 230 V rated lamp used at 240 V will achieve only 55% of its rated life (it will fail after about 550 hours instead of the average of 1,000 hours) but will be brighter and will run much hotter, possibly leading to overheating problems in some luminaires. The starting current for large concentrations of discharge lamps will increase dramatically, especially when they are very cold. High pressure sodium and metal halide lamps will show a significant change in colour output when run at higher voltage than their rating, and rechargeable batteries in 230 V rated emergency lighting luminaires will overheat and suffer drastic life reductions when fed at 240V"

The issue of supply voltage is not a simple matter, there are a lot more complex issues than touched upon in the above extract from a book written more than a decade ago, a lot of other things have happened too.

Incandescent bulbs have been legislated out, the lifetime reduction figures mentioned only applies to incandescent bulbs, not other types such as mains or HF flourescents or LED's all of which are far more efficient and longer lived than incandescents ( apart from the cheapo flash in a pan ccft's) and now far more significant numerically.

Many new domestic devices using switching convertors have a negative slope i.e. the current decreases as voltage increases, so act as constant power loads. So much of the impact assesment in the old article is out of date.

So if your line voltage is 240V don't worry, it is within tolerance, your simple heaters will deliver a bit more heat but most of your newer stuff will draw constant power or just slightly more and not be greatly impacted.

And Three Phase Motors will still work much better than single phase types when driven by a nice VFD. Nice maker and age too!

Billy.