Automatic Voltage Regulator

[Pierrot]

Thanks for the advise Crossy, here is my problem :

We have a house in the countryside with a serious problem of electricity supply. At some time the voltage can drop to 160V. The problem is with the water heater but mostly with the water pomp, we get our water from a well and in the future we would like add more pomps for irrigation. People advise us to get an electric pomp (cheaper than diesel they say) but with the above mentionned problem I'm not sure it's a good idea. To get an idea of the power of the irrigation pomp we need, the water is 400 m (distance) and 30 m (depth) from the tank.

They say we should purchase a "black box" that would solve our electricity problem. Not so sure how it works, they don't have any satisfactory explanation either. Does anybody has an idea of what they're talking about and if it's really works ?

[Crossy]

It really is a box (not usually black), you feed your iffy supply in one side and a miraculously stable 220V comes out the other. They use a principle called 'ferroresonance' to act as an automatically variable transformer. There are no batteries (it's not a UPS), they compensate for the lower voltage by pulling more current from the input side.

Your local electrical emporium will likely have them, they invariably say "Automatic Voltage Regulator" in English along with a couple of meters so you can see it's working.

They come in various capacities (Amps and Watts) and it's important to get one with enough oomph for your load. I would get several small ones rather than one big one to try to feed the whole house (unless it's a really small house).

I would get one for:-

• The TV
  
• The fridge/freezer
  
• Each Aircon
  
• Water pump
  
• Your PC, add a UPS too if the juice has a tendency to go off at random.
  

Don't bother for the water heater.

Adding one to your lighting circuit will prevent the lights from flickering and may increase the life of your lamps.

Install each unit right next to the equipment it is to protect for maximum effect.

[Pierrot]

What about the pomp? Actually I will need a pretty powerful pomp, so far my neighbours with similar land configuration have problem to get the water to the top of the land.

Is it the right place to discuss pomp problem ?

Also is solar panels a good option to compensate for power shortage? Our area knows from time to time a big influx of tourists which usually means power cut during peak hours.

[Crossy]

Yes, this is the right place to talk about the pump (pomp).

Is your water 30m below ground (borehole) or in a tank 30m below your house, each would require a different type of pump. If you currently have a diesel pump, what is its power and pipe size?

Solar for creating electricity is WAY too expensive to be practical here, however using it as a water pre-heater can save you considerable sums in electricity. You can easily make a solar water heater (try a Google search for some ideas)

[Pierrot]

Actually we currently have a pump for the well, I should probably get an AVR for it too, right ? But this one is working ok.

But what I'm talking about is a pump for an irrigation system. The highest point of the land, where we're going to install the tanks, is around 30 m above the ponds where going to get the water from, distance between the two points is around 400 m. I'm thinking of 2 tanks of 3x3 m. The size and how to make the tanks is an other problem.

What are your advise for the pump ? It seems a standard electric pump won't do it. My neighbour, with similar land configuration, is giving up. He's thinking now of either using a submerged pump or a diesel pump. Any suggestion ?

[Boksida]

To calculate what size or model of pump you need, this site is very helpful. It takes a little practice but is a great way to examine different possibilities. Even if you don't use a Grundfos pump it will tell what size you should be looking for.

[Crossy]

To calculate what size or model of pump you need, this site is very helpful. It takes a little practice but is a great way to examine different possibilities. Even if you don't use a Grundfos pump it will tell what size you should be looking for.

The direct link doesn't work mate Can you tell us how you got to the calculator, could be useful

Pierrot, you will certainly be able to use an electric pump. Whether it is economical by virtue of the cable length required etc. is only going to become evident when you size and price the pump and price the correct cable for it. You may also need to upgrade your electricity supply if you end up with a big unit

There's a whole bunch of variables, what you want to irrigate, drip feed or whatever. You may score better on the watering front in the farming forum

[Boksida]

To calculate what size or model of pump you need, this site is very helpful. It takes a little practice but is a great way to examine different possibilities. Even if you don't use a Grundfos pump it will tell what size you should be looking for.

The direct link doesn't work mate Can you tell us how you got to the calculator, could be useful

Crossy, it works for me but try googling "Grundfos Webcaps" and see if you can get to it from there.

[Crossy]

To calculate what size or model of pump you need, this site is very helpful. It takes a little practice but is a great way to examine different possibilities. Even if you don't use a Grundfos pump it will tell what size you should be looking for.

The direct link doesn't work mate Can you tell us how you got to the calculator, could be useful

Crossy, it works for me but try googling "Grundfos Webcaps" and see if you can get to it from there.

I got it to work by accessing it from the "Documentation & downloads" page here http://www.grundfos.co.uk/web/HOMEUK.NSF looks useful.

Direct link http://net.grundfos.com/Appl/WebCAPS/custom?userid=GB

[Naam]

It really is a box (not usually black), you feed your iffy supply in one side and a miraculously stable 220V comes out the other. They use a principle called 'ferroresonance' to act as an automatically variable transformer. There are no batteries (it's not a UPS), they compensate for the lower voltage by pulling more current from the input side.

what is the working range Crossy (minimum voltage to get an output of 220)?

[Crossy]

It really is a box (not usually black), you feed your iffy supply in one side and a miraculously stable 220V comes out the other. They use a principle called 'ferroresonance' to act as an automatically variable transformer. There are no batteries (it's not a UPS), they compensate for the lower voltage by pulling more current from the input side.

what is the working range Crossy (minimum voltage to get an output of 220)?

Inputs from around 160 - 280V for a constant 220V output, varies with cost of the unit (cheapies seem to fall over below 180V). If you have a constantly low voltage sticking a 10% boost autotransformer in front of the beastie will give it a fighting chance

This tap-changer reckons it's good down to 150v input http://www.line-conditioner.com/SLc-600-12...Conditioner.htm

[Pierrot]

Thank you for your advise, I'll take my pump problem to the Farming forum.

Regarding the AVR, if I understand well, its aim is to protect electric equipment from voltage variation but is useless when the problem is a lack of power, for a water heater for example ? The only other major problem inside the house is the microwave, sometime we even don't have enough power to warm up a cup of water.

I insist on the water heater because during winter temperature can drop to 10 C in the morning and hot water is not a luxury when you want to take a shower. Any solution, beside the water pre-heater you're talking about?

You say I may also need to upgrade my electricity supply , how ? It can be quite expensive where I am, you need to buy your own poles, own cables, own transformer ...

[tjo o tjim]

For motors, I would usually recommend using a Variable Frequency Drive (VFD) in place of an automatic voltage regulator, especially if the motor cycles on and off frequently. If your voltage really is as low as 160V, you would need a buck/boost transformer as well though (minimum operating voltage is usually around 170V).

The missing part of your problem is how much water you need per day-- how fast the pump needs to fill the tanks. If you want to fill those two tanks in 24 hours, you are looking at about 5kW with a 100mm pipe if my math is right.

The cheapest long-term solution is to go for three-phase power if your pump is going to be over about 5 kW. A VFD can be set up with single phase power initially, and converted to three phase when it is available. If you have problems now, adding 5kW of load is going to only make things worse. Likewise, the AVRs will increase the current on your utility lines by over 30%, which will make the voltage for everything else even lower. AVRs are great when 90% of your equipment is fine either way and only 10% cares. When you hit a 50-50 split you really need to address the source of the problem.

[Crossy]

I agree with what Tim says ^^^ although a VFVD drive is an expensive solution. You may find that a diesel pump is actually the best option.

Regarding the AVR, if I understand well, its aim is to protect electric equipment from voltage variation but is useless when the problem is a lack of power, for a water heater for example ? The only other major problem inside the house is the microwave, sometime we even don't have enough power to warm up a cup of water. An AVR will make your microwave happier.

I insist on the water heater because during winter temperature can drop to 10 C in the morning and hot water is not a luxury when you want to take a shower. Any solution, beside the water pre-heater you're talking about? The reason I didn't suggest an AVR for the water heater is simply that it will continue to work even when the voltage is low, it just won't have the same output. A unit big enough to drive the heater will likely cost more than a bigger heater (but of course if you already have power issues.....). You could investigate a gas water heater, obviously these bring the issue of running out of gas on a chilly morning but can give loads of hot water without upgrading your electricity supply $$$$$$.

You say I may also need to upgrade my electricity supply , how ? It can be quite expensive where I am, you need to buy your own poles, own cables, own transformer ... You need to examine what you have, both load wise and supply wise and report back. Transformer size, distance from the transformer to the house, cable size from the transformer, what you are running in the house, what else is on the same transformer etc. We can get a much clearer picture of what your issues are and how to address them.

EDIT and take a look at the meter, is it a 5/15, 15/45 or 30/100 type?

[dotcom]

A submersible borehole pump will be your best option.

[Pierrot]

You say I may also need to upgrade my electricity supply , how ? It can be quite expensive where I am, you need to buy your own poles, own cables, own transformer ... You need to examine what you have, both load wise and supply wise and report back. Transformer size, distance from the transformer to the house, cable size from the transformer, what you are running in the house, what else is on the same transformer etc. We can get a much clearer picture of what your issues are and how to address them.

EDIT and take a look at the meter, is it a 5/15, 15/45 or 30/100 type?

We share the same transformer with a number of households in the neighborhood, so the load is not easy to estimate and may vary. For the house by itself, it’s very little, basic household appliances, we even don’t have air cond. My main concern for the time being is the irrigation system, we may need to add a number of pumps, and probably powerful ones. Also one day we may want to upgrade the comfort in the house.

One thing I’m not very clear with is the policy of electricity supply in rural Thailand. It seems that below a certain number of household in a given area, all installation are at the charge of the users (poles, cables …), above that number, it’s the “government” that will pay. One of our neighbor (a temple) want to upgrade his electricity supply to 3 phases and offer us to share the installation cost, which will solve a number of problems, but then the local electricity department tells us it’s not possible as electricity for temple is subsidized. As everybody has its individual meter, where is the problem ?

A submersible borehole pump will be your best option.

That's also the solution my neighbor advises, but why ?

Anyway, he will try first so we will see if it really works.

[tjo o tjim]

That's also the solution my neighbor advises, but why ?

Submersible pumps don't need priming and generally aren't subject to cavitation. Said another way, more simple and less maintenance.

As for the transformer and the utility, usually three-phase transformers that are "dedicated" to a customer are purchased by that customer. You could try and get the utility to upgrade the transformer in the area to three phase, and then pull a three phase feed from there, but PEA won't always let you do that.

Crossy's point on the meter is to look at your utility meter to see the numbers on it for size, not to meter the total load on the transformer.

[Pierrot]

Submersible pumps don't need priming and generally aren't subject to cavitation. Said another way, more simple and less maintenance.

But the problem is a "classical" pump is not powerful enough to bring the water to the tank, will a submersible pump be more efficient ?

As for the transformer and the utility, usually three-phase transformers that are "dedicated" to a customer are purchased by that customer. You could try and get the utility to upgrade the transformer in the area to three phase, and then pull a three phase feed from there, but PEA won't always let you do that.

Crossy's point on the meter is to look at your utility meter to see the numbers on it for size, not to meter the total load on the transformer.

That was my understanding, based on our discussion with the temple people, but as you said it's seems the government office doesn't agree. Why ?

[mdechgan]

An AVR just keeps the voltage stable by controlling the current to keep the frequency up. Its like superfast switching power supply. We use one for our machinery controls. However it is a very expensive piece of equipment an I don't think it helps that much for a home unless you have really sensitive equipment. We use it because our voltage fluctualtes from 210V-250V and it really screws up the rectifiers in our systems.

But if your volts drop to 160V I think it is more of a power supply problem. Must be really long runs from the local transformer or the local transformer doesn't have enough capacity.

Are you using alot of power? You can buy a transformer if you want to make an investment. Its a really big investment but most factories and shops do buy them outright.

[Crossy]

Nah, the little beasties we're discussing are ferroresonant transformers, no real electronics and not expensive.

You are absolutely correct, the OP has a power supply problem, but PEA are notoriously bad at fixing what they see as a non-issue "the light is on, no problem".

Anything with an induction motor (fridge, aircon, water pump) gets upset and overheats at low input voltages and can have its life seriously reduced, same with your electronics, PC, telly etc.

Yes, they are a stop-gap solution but they do most definately work.

[gdhm]

Nah, the little beasties we're discussing are ferroresonant transformers, no real electronics and not expensive.

You are absolutely correct, the OP has a power supply problem, but PEA are notoriously bad at fixing what they see as a non-issue "the light is on, no problem".

Anything with an induction motor (fridge, aircon, water pump) gets upset and overheats at low input voltages and can have its life seriously reduced, same with your electronics, PC, telly etc.

Yes, they are a stop-gap solution but they do most definately work.

Hi Crossy,

I do not recall anybody giving any idea of pricing in Thailand (or known supplier) for ferroresonant transformers that you suggest will suit most of us with variable and Volts (mine 178V to 228V) typically 178V to 185V at peak times of night and early morning.

I have searched the Internet but only find western suppliers and nothing so far on Thai suppliers or Thai distributors of Chinese or other Asian suppliers and certainly not pricing.

I do not know if we are talking really cheap. cheapish or or moderately expensive.

Are you able to give us a "ball park" estimate of the sort of price (in Baht) for individual AVRs purchased in Thailand if items like

1) TV (tube based)

2) Freezer (medium size)

3) Fridge/Freezer

4) An Aircon rated 18,000 BTU (I Have 4 and one 12,000 BTU unit (seldom used except one 18,000 BTU unit in my bedroom which is used every night and at times during the day when I escape the heat of the day ). I assume at that BTU and potential power requirements this AVR would need to be quite big and costly if to cope OK.

Thanks,

Dave

[dotcom]

Crossy. Is there a chart showing BTU (of air cons) versus the current (amperage) they draw?

I'm guessing a 12,000 btu air draws about 10 amps & gdhm's 18,000 btu unit 16 amps.

Thanks

[Crossy]

Are you able to give us a "ball park" estimate of the sort of price (in Baht) for individual AVRs purchased in Thailand if items like

1) TV (tube based)

2) Freezer (medium size)

3) Fridge/Freezer

4) An Aircon rated 18,000 BTU

18,000 BTU aircon will pull about 2kW (10A), 12,000 BTU pulls about 1kW (5A) figures from a Google search. Double those numbers for the kVA rating of your AVR (they are very robust to overload from motor startup currents).

Telly, 250W or so (check the rating on the back)

Freezer / fridge also 250W or so (check the rating on the back)

Units for your telly and fridge are IIRC about 500-1000 Baht, bigger ones suitable for aircon are 3-4000 Baht.

Best bet is to go to your local electrical emporium and ask, they WILL have units it's just a case of getting them to understand what you want. Luckily they tend to say "AVR", "Automatic Voltage Regulator" or maybe "AC Voltage Stabilizer" on the front, some have meters to show it's working.

The big electronics supermarket in Zeer Rangsit has them in all sizes up to 10kVA.

EDIT just been down to the local supermarket (in Bangalore), they have 300VA units (telly, fridge) for 750 Rupees, 3kVA for 1500 Rupees, 4kVA for 2100 Rupees and 5kVA for 3200 Rupees. At the current rate 100 Rupees is about 75 Baht.

Sorry can't bring any back, wayyyyy too heavy

[gdhm]

Thanks Crossy, Great News as much cheaper than I feared . May I ask two final question on AVRs.

1) Are they 100% silent or do they hum or give off a high frequency that you can hear when your surroundings are quiet (e.g. Night time).

2) any relevant downsides (apart from having an AVR next to the item it is helping).

Will give the PEA a month (but will investigate local prices and sources) and if no real progress I will go down this course for the 2 fridges and most used Air cons (3 are almost never used).

That reminds me of another question (forgive me) on aircons

A qualified (in UK and Spain) electrician former friend of mine (we have lost contact) suggested to me that aircons should be run from time to time or else they are prone to de-gassing. When I sold my house in Spain a Panasonic aircon had de-gassed following a year of non use.

This I do not understand and am wondering if my friend was mistaken. The reason I do not understand is that surely gas will escape IF there is a leak site. I do not understand how non use would allow a loss of gas (unless there was a problem already or a new one developed causing a leak site).

My former friend was usually highly accurate on electrical related matters but this one I do not understand and am wondering if you know anything or whether he is mistaken on this one. If he is correct (whether reason of de-gassing or not) that aircons should be run at intervals if not used normally and if so can you suggest a routine (frequency/running time) that would be advisable.

Thanks

Dave

[tjo o tjim]

The ferro-resonant transformers biggest downside is poor efficiency. They do hum as well, proportional to load usually.

I was always told that running the aircon will mainly benefit the system by maintaining lubrication on the compressor. Gas pressure shouldn't be impacted by not running; hot gas temperature is far above ambient temperature so there should not be any excessive pressure build-up.

[Crossy]

The ferro-resonant transformers biggest downside is poor efficiency. They do hum as well, proportional to load usually.

Yup ^^^, certainly poor efficiency compared to a normal transformer, expect around 90% efficiency at 80% of full load. When lightly loaded the iron loss is significant and the efficiency very poor. Rule one, run your ferro near maximum load

The other (somewhat more expensive ) AVR is a "tap-changer", this uses electronics to adjust the secondary winding on a transformer. They don't give smooth regulation but are rather more efficient.

The ones we have on the aircon do hum on load, but since they're next to the compressor you can't hear them. The baby (300VA) unit on the TV is barely audible even in a quiet room.