Building Construction, Renovation, Maintenance & Advice

Electric Motors, Coils and Voltage Stabilisers

"Danish Bacon"

“What's for tea mum?”
“Bacon, Christian.”
“What, bacon again mum? Can't we have beans on toast for a change”
“We live in Denmark, we eat bacon.”
“Aw mum.”
“Hands.”
“What?”
“Hands, Christian. Don't forget to wash your hands.”

The washing of hands before eating was always a bit of a thing in Denmark, mothers became paranoid about hygiene after watching their sons scratch their bums then pick their noses (yes, yes I know, too much information). In fact the catchcry “Hands Christian” became such a common phrase in the land of 'smoked bum of pig' that Anders Van Strudelhagen, who worked as the registrar of births, marriages and deaths (what a boring job; you think filling in an immigration form is boring; Anders Van Strudelhagen spent all day every day writing peoples names and personal details on forms) in a particularly stupefying fit of total boredom accidentally started adding the word Hands onto the names of little boys he registered and this is why we have Hands Christian Andersen and, of course, a friend of his and today's hero - Hands Christian Orsted.

But Christian would often miss his tea. To say he didn't have a good sense of direction is a bit of an understatement really. He would set off to the bathroom and get totally lost on the way and his mother would find him 2 hours later walking round in circles in the coal cellar.

Eventually his mother in shear frustration hung a compass on a string round his neck.

“The living room is to the North” she'd say, “follow the needle.”

Everything went well for a while but then one christmas Christian suddenly went AWOL again. His mother eventually found him standing next to the christmas tree. He was totally confused.

“I don't know which way to go” he wailed.
“Use your compass” said his mother.
“But the needle keeps moving everytime the christmas tree lights blink on and off.”

The relationship between electricity and magnetism

And so it was that in 1820 Hans Christian Orsted first discovered the close relationship between electricity and magnetism.

At this stage our tale takes a somewhat technical turn and, for many of you, may be as interesting as reading the 'Stampcollectors Monthly' or a diatribe on the nocturnal activities of the inner mongolian warthog (come to think about that might be far more interesting).

He started messing around in his garden shed (blokes do that sort of thing). He found that if you connect a wire to a battery and electricity flows through the wire it creates magnetism that flows around the wire. The magnetic field flows either clockwise or anticlockwise depending on which way the electricity is flowing.

Electric copper coils

If we get a long piece of bare copper wire and wind it a squillion times around a cardboard tube (empty bogrolls work really well) we make a copper coil.

If we now connect our coil to a battery we find we have a magnetic field running through the tube. Now if we put a lump of iron inside the tube and we switch on the electric current the iron will shoot out of the tube like vomit from a Rivetcatcher on a Saturday night.

It was Hans Christian Orsted's observations that helped us to understand the basic phenomenon linking electricity, magnetism and moving lumps of iron which is, of course, the basis of the majority of electrical applications we use in our daily lives.

The basis for the electric motor

By rotating a coil of copper wire in a magnetic field we generate electricity in power stations, motor car alternators, gensets, windmills, etc. By using electricity to flow through a copper coil we generate a magnetic field and move iron which makes an electric motor rotate to drive our water pump, air conditioner and electric nasal hair remover. If we switch the electric current on and off really, really fast we can make the middle of a loudspeaker move backwards and forwards to play Beethoven's 1812 overture complete with bells and guns. Amazing!

Our lives are surrounded by millions (well dozens anyway) of copper coils with those sneaky little electrons hurtling around and producing magnetic fields.

Come on wake up, I am inexorably getting closer to today's topic. There is another very common use for copper coils and magnetic fields.

When our national electricity provider is gracious enough to allow us to have a few electrons now and again, it should come to us at a healthy 220 volts. The American authorities are rather tight fisted and they only give the dudes and chicks a mere 110 volts while the welfare oriented nature of the British government, endlessly trying to build the morale of their usually rather peeved population, gives an impressive 240 volts.

Transformers

But of course many things in our lives don't want 220 volts, that is rather a lot of 'erbs to stick into granny's hearing aid isn't it? Granny will probably be much happier with only about 6 volts. So how do we stop granny getting an earful of 'erbs? We use a transformer to reduce the voltage.

We talked above about a coil of copper wire to produce a magnetic field. Now if we make a second coil of wire and we put it into the same magnetic field (we can wind it over the top of the first coil) we will find that when we put electricity into the first coil, this will generate a magnetic field which in turn will 'induce' electricity in the second coil.

Now comes the clever bit, if the second coil is exactly the same as the first we will get the same voltage coming out as we have going in but, if we change the second coil (we might make the wire thicker or make it longer or shorter) we will get a different voltage coming out. If the second coil is only half the length of the first when we put 220 volts in we will only get 110 volts out.

This is how a transformer works and we find transformers in televisions, flourescent lights, refrigerators, computers, in fact most electrical items we use. The power supply that we use for a laptop computer or a charger for a mobile phone is basically a transformer on a plastic box.

So what use is all this information? A very good question.

Voltage fluctuations can damage electronic equipment

Demand for electricity in Bali is greater than PLN (the nation's electricity supplier) can supply and as a result most of us have ongoing problems. A common problem (although many of us don't go around with a meter to check so we don't know) is that the voltage of our power supply fluctuates. It should be 220 volts but, when too many people are connected and drawing power, the voltage often drops to 180 volts (that's low) and sometimes I have known the voltage to drop as low as 150 volts (that's very low).

Anything that has an electrical motor such as a fridge, a water pump or an air conditioner needs a certain amount of power to run. If the voltage drops then the flow of electricity (the current - amps) has to increase to compensate. Now higher currents have a nasty way of harming things such as damaging sensitive equipment or electronic control circuits, wires might start to get hot. It is current that can give you an ongoing negative survival situation and it is also current that makes your circuit breakers cut out.

The voltage drops we from PLN can cause all sorts of problems so what can we do?

We can install a voltage stabiliser.

A what?

A voltage stabiliser smoothes out fluctations

A voltage stabiliser, voltage regulator, stavolt, call it what you will, it is a device that increases the voltage back up to the 220 volts we want.

So how do we do that?

Hmm, what we have to do is make a transformer that continually adjusts itself. It looks at the voltage coming in and, using an adjustable transformer, it turns it into the correct 220 volts going out.

A voltage stabiliser has a large circular transformer with two coils, an input coil which is receiving power from our national grid and an output coil which is delivering power to our house. A contactor rotates from the centre of the transformer and slides along the coil so it can lengthen or shorten the coil and so adjust the voltage.

Voltage stabilisers we use in domestic or business electrical supplies are heavy devices. You will need one for each phase of power, if you have a single phase supply you only need one, if you have a 3 phase supply you will need 3 single phase stabilisers or a large 3 phase stabiliser. Expect to pay around Rp6 million per phase excluding installation and any extra cabling.

Standard units have a minimum power capacity of 5 kilowatts and go up from there.

These units can increase or decrease voltage within reasonable limits typically handling anything from 160 volts to 240 volts and converting it back to 220 volts. They have protection switches so that if the incoming supply drops below 160 volts or above 240 volts they will switch themselves off.

Advantages of voltage stabilisers

Advantages are that they provide a constant, stable 220 volts protecting your valuable electrical equipment (and reducing blown lightbulbs). They remove those variations we all know about when the lights start to go dim or the telly goes on the blink. They also provide surge protection, absorbing sudden spikes in the power that can do damage.

Disadvantages of voltage stabilisers

Disadvantages are that they use a certain amount of power to operate so they will put the electricity bills up a bit and, if you are living close to your power limit, you may find an increase in the frequency your PLN circuit breaker (the big blue switch!) cuts out.

Another downside is that to boost a low voltage, they need to draw more current from the PLN supply and this might also increase the likelihood of the PLN circuit breaker cutting out depending on how much power you are using and how much PLN supply you have.

There are many different brands of voltage regulator which can get confusing at times. It is all to do with the quality of manufacture. My suggested brands are all Japanese which, in order of preference, are Kiumatsu, Yuritzu and Matsuyama. Matsuyama have a good backup maintenance service in Bali. I avoid Chinese made voltage stabilisers one particular one of which (I mention no names) may only last 6 months. Note that many of the Chinese ones use Japanese sounding names so care is needed. There is a very interesting book, Poorly Made In China by Paul Midler, which goes a long way to explaining why quality is an issue with Chinese made products.

Finally you will find small voltage regulators for use with computers. Usually with small steel cases painted red or orange these are not in the same league as the serious units mentioned above and do not provide the same self adjusting voltage control. They make very good door stops and rather than buy one of these I would suggest you invest in a UPS (Uninterrupted Power Supply) for computers.

With that I will finish, my bacon butty is ready and I've got to wash my hands.

Copyright © Phil Wilson 2011
This article or any part of it cannot be copied or reproduced without permission from the copyright owner.

17 July 2017 Copyright © Mr Fixit,
Jl Bypass Ngurah Rai, Gg Penyu No 1, Sanur, Bali 80228, Indonesia
Telephone: +62-361-288-789, Fax:+62-361-284-180