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KhaoYai

Low Voltage???

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I was going to try to get an answer to this by sending a PM to a 'certain person' 😀 but I think the replies could be useful to others.

 

I suspect that I am not getting a full 220v a certain times of the day.  I'm a light sleeper so it doesn't take much to wake me - I've been back in Thailand for just over a week and each time I sleep at my house, I'm woken between 4.30am and 5.30am by the celing fan in my bedroom making a buzzing noise - it works but makes a noise and appears slower.  Also, my bedside lamps are the touch type - as in you just tap them to turn them on or off and they have 3 brightness levels. When this (presumed) low voltage occurs, the bedside lamps won't work at all - if they're off they won't turn on and if they're on they won't turn off. Anything else plugged in to the same socket works. My fridge/freezer also seems to be noisier at this time.

 

My presumtion is that all of these things are the result of a low voltage in my PEA supply. I'm no electrician but I know that certain types of device are classed as 'induction' and I believe they need a higher rate of power to start them etc. I think electric motors (ceiling fans) are induction but I have no idea how the bedside lamps work.

 

I've seen other people post about low voltage supplies so I know its nothing new in Thailand but my experience of low voltage supplies in the UK tells me it can damage certain household appliances.  Around 20 years ago (in the UK) I experienced a low voltage fault which damaged the motors in 2 freezers.  The electricity supplier admitted the fault and paid for the appliances to be repaired but they told me that if I ever experienced a low voltage fault again, I must turn such appliances off.  I can't see the PEA here doing the same but I want to avoid any damage to my equipment.

 

Can anyone confirm that what I'm experiencing is indeed 'low voltage' and suggest what can be done - if anything?

 

An electrician tested my supply a couple of days ago and his meter read 215v. This was in the afternoon and  there was no problem with the fans or lights at that time - I know its supposed to be 220v but I would expect a little variation so 215v is probably OK??? No idea what the voltage is when the fault occurs but I'd guess its caused by people getting ready for work and turning their electric showers etc. on???

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You could buy a cheap voltage tester, be sure to click on alternating Current. When you think the voltage has dropped, get up and test the voltage, then you can approach the electric co if it has dropped a lot...

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42 minutes ago, KhaoYai said:

Can anyone confirm that what I'm experiencing is indeed 'low voltage' and suggest what can be done - if anything?

 

An electrician tested my supply a couple of days ago and his meter read 215v. This was in the afternoon and  there was no problem with the fans or lights at that time - I know its supposed to be 220v but I would expect a little variation so 215v is probably OK??? No idea what the voltage is when the fault occurs but I'd guess its caused by people getting ready for work and turning their electric showers etc. on???

Almost certainly it’s very low voltage, the supply down to 200V and a bit lower during peak load is considered normal you are probably well under that.

 

You have 3 basic options which are in order of cost and ease of getting done 

1) install an under/over voltage control with its contactor like this

50284BC9-A1E3-40E7-A642-779F997C6F52.jpeg.e1ddffff8345f4505be1ade3fb5fe222.jpeg
probably 1,000~2,000 installed. It cuts your supply when too low and restores it when it’s back.

 

2) install an AVR probably 10,000~30,000 depending on size.

 

3) get the PEA to improve your supply, possible, but then so are flying pigs (but you don’t want to be under them when they land) 😉 

 

Edited by sometimewoodworker
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8 hours ago, sometimewoodworker said:

1) install an under/over voltage control with its contactor like this

What is your settings and can you explain why you choose these numbers?

The picture is not very clear at the numbers but it looks like your safe voltage is between 180 and 245.

 

Here I am using 170-270.

Fridge is inverter type which still operates at 140 volt, and all other equipment are using switched power supplies (mostly 80v-265v).

Even the led tubes, which are CC and not CV operated, running on 230v can work at 65v.

No incandescent lights. The only that could be affected by brownouts are one ceiling fan and two swingers on pegs.

 

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45 minutes ago, Metropolitian said:

What is your settings and can you explain why you choose these numbers?

The picture is not very clear at the numbers but it looks like your safe voltage is between 180 and 245.

 

Here I am using 170-270.

Fridge is inverter type which still operates at 140 volt, and all other equipment are using switched power supplies (mostly 80v-265v).

Even the led tubes, which are CC and not CV operated, running on 230v can work at 65v.

No incandescent lights. The only that could be affected by brownouts are one ceiling fan and two swingers on pegs.

 

That’s about right, I have a few machines that would probably not be happy with a lower voltage and quite a few items will be significantly damaged by a high voltage like the one you have selected. 
 

the PEA voltage around this area virtually never goes over 230 so 245 and over will be caused by a major problem.

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Yeah, it does sound like seriously under-voltage.

 

To be sure you can get a cheap digital multimeter (even Tesco have them) and check the voltage for yourself, both during the day and when you see the problem.

 

As to a solution, that really depends what you want to do.

 

Modern "inverter" appliances are good for a pretty wide supply range, LED lamps seem to work on almost anything. Appliances with induction motors (fans, fridges, water pumps) don't like under voltage and can be damaged (or have their life reduced).

 

The supply authority is unlikely to be very helpful "you have electric, no problem" although it certainly wouldn't hurt to talk to them.

 

You're left with two choices (as others have posted):-

  • Kill the power when the supply is low. you could do this only to sensitive items the units are pretty cheap.
  • regulate the voltage with an AVR, you could also do this to only sensitive items (ours does the whole house except the water heaters, there's a pinned thread all about it).

Cheap low voltage cut out here https://www.aliexpress.com/item/4000129243949.html

 

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One with a few more bells and whistles https://www.aliexpress.com/item/4000072178912.html

 

Hca89d000aab04c8c9500d2e7739bd0161.jpg

 

Both of those would need to go in a cheap DIN box, a few Baht from the electrical retailers.

 

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On 1/25/2020 at 2:00 PM, NilSS said:

There is a fourth option which no one seems to consider. In my experience, a lot of the time undervoltages are caused by bi-metallic corrosion on the clamps connecting consumers wires to the phase of the PEA lines, it's a VERY common problem. I've changed/cleaned up countless corroded connections over the years at our site. A common problem I have is aluminium bolted (or even just taped) to steel or copper. A few years is all it takes and your voltage is all over the place. If it's intermittent and at certain times of the day, it could still be the culprit as the undervoltage may only manifest under load.

 

I've never found a stockist of bimetallic clamps in Thailand. I've considered ordering them from China because I get through quite a few of them. The solution I've come up with is to use brass clamps, and make the connection water and air tight with acrylic spray paint. Works very well.

 

Just a thought, but it's what I'd be checking first. It's not something you want to be doing yourself, it's very dangerous work. I only do it myself because it's a private power grid and I have the experience and equipment. Good luck explaining it to a moron from the PEA.

 

 

 

 

 

 

I was looking for insulated lines taps myself. I didn't find them online locally,.. 

https://www.google.com/search?q=Iine+tap+service+electrical&tbm=isch&ved=2ahUKEwjpzbXHzrrnAhWSIisKHfBEA3IQ2-cCegQIABAC&oq=Iine+tap+service+electrical&gs_l=mobile-gws-wiz-img.3..30i10.2342.8643..8672...1.0..1.135.940.0j8......0....1.qIN0R98VzRA&ei=CtA6XumgA5LFrAHwiY2QBw&bih=612&biw=360&client=ms-android-samsung&hl=en#imgrc=gPcuMj1EW9rJWM

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Thanks for your comments. However, I don't think that's the problem, my supply is new, I upgraded to 30amp last year so the cable and connections are only just over a year old.

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