Low Voltage in Chiang Mai

[bprhodes]

I noticed a couple of weeks ago that the overload on my pool pump (see picture) was cycling off and on every 2-3 sec. Pool company replaced it with no effect.

 

On further experimentation, I noticed that the cycling would stop if I turned of all my A/Cs.

 

Today, I checked the voltage in an outlet and it was 188-192 V.

 

Questions:

 

1. Could this low voltage be the cause of the pool pump overload cycling?

 

2. Is the low voltage a result of the very hot weather we are having in Chiang Mai (43C)?

 

3. Can this low voltage do any damage to the A/C, pool electronics, etc?

 

4. Should this low voltage get reported to my PEA? Can they or I do anything to ensure proper voltage?

 

Please answer in dummy terms, I am pretty ignorant about electricity. I am willing to spend money to ensure a reliable electrical supply that won’t kill me one day.

 

PS: I have single phase - I was told that 3-phase was not available.

 

 

 

 

[johng]

How many aircons ?

2. Yes too many aircons

3. Possibly

4. Yes. They can install a bigger transformer and thicker wires.
(Expensive)

You could ask for a 45 or 60 Amp supply.

[bprhodes]

How many aircons ?

2. Yes too many aircons

3. Possibly

4. Yes. They can install a bigger transformer and thicker wires.
(Expensive)

You could ask for a 45 or 60 Amp supply.

Thanks for the answers. I have 4 A/C units but normally only 1 or 2 running at the same time, often with my pool pump going to. Also have 3 hot water heaters, oven, microwave, etc.

Would a voltage regulator solve my issues and protect my electronics?

[Crossy]

What size meter do you have?

 

Check on the poles outside, if there are 4 wires then 3-phase is available (post photos if stuck).

 

An AVR will do good (see my pinned thread) but don't run your water heaters through it.

 

[bprhodes]

What size meter do you have?
 
Check on the poles outside, if there are 4 wires then 3-phase is available (post photos if stuck).
 
An AVR will do good (see my pinned thread) but don't run your water heaters through it.
 

We have the standard 1 phase 2 wire, 15(45)W meter. All the meters for the nearby homes are the same.

For the purposes of calculating the size of my AVR, I assume that watts ~ kVA right?

Also, can you recommend a whole house Surge protector?

Thanks!

[Crossy]

Check out this pinned thread for the whys and wherefores of AVRs, also check my thread on VEG AVRs.

 

 

 

[bankruatsteve]

1 hour ago, Crossy said:

An AVR will do good (see my pinned thread) but don't run your water heaters through it.

Please explain Crossy.  In my case, it is not feasible to isolate the heaters.  Will that be problematic at some point (it doesn't seem to be an issue so far)?

[mahjongguy]

I'd begin with a visit to the PEA office. This is a situation they can fix if they are prodded to do so.

 

For sure, 188 volts is low enough to do a lot of damage, especially to some electronic items. 

[PatOngo]

What you need is.....

 

[worgeordie]

Not only low voltage,and low water pressure,but when

it gets a bit windy or starts to rain,off it goes,just wonder

what investment is been made in utilities,as more and

more properties are been built here,I would prefer they

made the utilities reliable,than spend Billions on war 

weapons.........but that will never happen.

regards worgeorddie

[Crossy]

4 hours ago, bankruatsteve said:

Please explain Crossy.  In my case, it is not feasible to isolate the heaters.  Will that be problematic at some point (it doesn't seem to be an issue so far)?

 

Main reason is that the water heaters don't actually need the AVR and therefore you can use a smaller (cheaper) unit.

 

BUT also.

 

Water heaters are essentially a constant-resistance load, as the voltage decreases the current drawn decreases in proportion so they actually self-protect your supply.

 

Put them on the output of your AVR and they become a costant-power load, no matter what the input voltage to the AVR your heater will be pulling rated power (and therefore the associated current at the AVR input). The current can get BIG very quickly if you have a typical "farang" water heater (say 6kW).

 

Let's do some sums using our water heater (6kW) and measured supply source impedance (0.5 ohms).

 

Firstly with the heater before the AVR.

Heater is rated 6kW at 220V so it has a resistance of around 8 ohms.

Connecting that to our supply will draw 220/(8+0.5) = 25.8A with about 206V across the heater.

Heater will be developing about 5.3kW

 

Now lets put the heater on the AVR output

Heater is supplied with a constant 220V so is always 6kW

Initially our 6kW pulls the supply down to 206V (as above).

The AVR then adjusts itself to maintain 220V and pulls 29A from the supply.

At 29A the voltage is now down to 205V and the AVR adjusts itself a bit more.

Now at 205V our 6kW is just under 30A (and we can keep iterating here).

 

So we are now hauling a good 4A more from our supply than we would with the heater directly connected.

 

On a bad evening our supply can start at 200V due to other loads outside our property.

 

In this case with the heater on the AVR starts at 28A pulling the supply to 186V.

At 186V 6kW is 32A and the supply goes down to 184V (keep iterating if you like).

 

Turn on your aircon and the kettle (say 3kW together) and suddenly you are pulling 52A from your 15/45 despite the load only being 9kW at 220V (about 41A).

 

If you have a slightly poorer supply then there is a possibility of popping your 50A incoming breaker or (worse) causing the supply to collapse and cutting everyone off. 

 

It may not give you an issue other than popping your incomer of course.

 

EDIT The above is a very simplistic view, the real world could be better or worse (think if your neigbours also have AVRs). As an experiment I tried our heaters on the regulated side, saw the input currents, became frightened and moved the heaters to the incoming side ????

 

 

 

 

 

[Crossy]

3 hours ago, Crossy said:

On a bad evening our supply can start at 200V due to other loads outside our property.

 

In this case with the heater on the AVR starts at 28A pulling the supply to 186V.

At 186V 6kW is 32A and the supply goes down to 184V (keep iterating if you like).

 

Turn on your aircon and the kettle (say 3kW together) and suddenly you are pulling 52A from your 15/45 despite the load only being 9kW at 220V (about 41A).

 

This example is with the water heater on the output of the AVR. For contrast this is what happens if the heater is before the AVR.

 

6kW water heater plus 3kW "domestic" load. Starting voltage at 200V.

 

Water heater will pull 25A and drag the supply down to 187V.

3kW @ 187V will pull 16A and drag the supply down a further 8V = 179V

 

At 179V the water heater will draw slightly less at 23.5A (it will actually allow the supply to rise slightly)

 

So we are pulling around 16 + 23 A from the supply = 39A as opposed to 52A if you put the water heater on the regulated side!

 

That 13A could be the difference between the supply collapsing and it remaining stable but low.

 

 

[Crossy]

For interest.

 

From my AVR installation thread, the actual measured behaviour of our supply.

 

 

 

[sometimewoodworker]

Are you being charged more for power are you drawing when you supply is very low, making the assumption that your AVR is 100% efficient (I know you will have some losses but ignoring them)?

 

 

[opensea]

It could be that there's too much demand on the circuit, that's why it would stop cycling when you turn off the A/C... There might be an undervoltage relay in the pump and if it's getting juice intermittenrtly it will power off and on.  What are the AC compressors doing when the pool pump cycles off and on?  Are they cycling off and on too? Sounds like improper wiring.  And by wiring I don't mean improper wires, I mean the circuit is not designed properly. It's drawing too many amps with everything on. As far as damage, the cycling could cause extra wear and tear on machinery, pumps and electronics. Electricity, aside from making things work also is very hot (mainly generated from amperage), and by the heating and cooling it generates in electronics and machinery it can cause things to wear out... Expanding and contracting with temperature changes.  Slag can also build up on contacts and result in bad continuity. It can also cause fires.

 

It could also be that you have a short or ground somewhere in your AC.  This is assuming that the wiring is correct and the circuit can handle the load when everything is on... AC, pool pump, etc..  You can isolate a ground or short by turning on each component in the circuit individually and seeing if it trips or if there is intermittent power.  Look for odd behavior in each individual leg of the circuit. Electricity can be hard to "see".  If you have a multi-meter and know how to use it you can use the meter to for look and find problems, either by chasing voltage or securing power and checking for resistance.  But you have to know how to do it and know what you're looking for.  And you probably would not be asking this if you knew how to use one.

 

Each circuit is designed to allow a certain amount of amps going through it.  You can check to see how many amps each "load", or piece of machinery, on that particular circuit demands and simply add them up.  If it is at or above what the circuit is designed for it can cause problems and at the worst cause fires.  Electricity is very hot. Instantly hot. You can check this with a meter too, but don't do it if you don't know how to. 

 

Anyway,  it sounds like you either are having an undervoltage problem and/or the circuit was not designed properly.  If you have an undervoltage problem, ie. there's not enough volts coming into the circuit, then somebody who knows what they're doing needs to re-wire the circuit before it comes into your house.  Are there other electrical problems in your house... or just the poolr pump?  

 

When motors first start up - and motors are what make your pumps and compressors work - they demand about 20 times their rated amperage.  So if your pool pump has a rated amperage of 10 amps, when it starts it will demand 200 amps to get going, then quickly ramp down to it's normal amp rating, or load.  This alone can cause something to trip if it's not wired right.  If your pump is cycling on and off every 2 to 3 seconds it's pretty much at that starting amperage the whole time, then trips off, then starts... just thinking but maybe the circuit is just not designed right and there's too much demand on it... 

 

If fuses have not blown, then your amps are ok, generally. Hope this helps but I'm rambling. Good luck

 

 

Edited May 2, 2019 by opensea

[Crossy]

9 hours ago, sometimewoodworker said:

Are you being charged more for power are you drawing when you supply is very low, making the assumption that your AVR is 100% efficient (I know you will have some losses but ignoring them)?

 

No.

 

Your electricity meter is a true Watt/Hour meter, it senses voltage, current and phase-angle (power factor) so you are only charged for the energy you consume.

 

Of course, like all things in measurement, take it outside its designed operating range and it will lose accuracy.

 

[bprhodes]

What size meter do you have?
 
Check on the poles outside, if there are 4 wires then 3-phase is available (post photos if stuck).
 
An AVR will do good (see my pinned thread) but don't run your water heaters through it.
 

I’ve done some observing using a multimeter. Virtually anytime I turn on a high wattage devise (AC, espresso maker, hob, etc.), I get a significant voltage drop. The pool pump only cycles if the voltage drops below 200. So just 1 AC+hob will usually do it. The voltage drop is worse during late afternoon (peak demand). However, with nothing on but low amp stuff, the voltage is fairly steady at 219-220.

In my simple mind, it seems the amount of electricity my 15/45 line is supplying is insufficient. A voltage regulator would seem to be a bandaid. The regulator would try to pull more amps to boost the voltage, but if the amps aren’t there it would ultimately fail to regulate or trip the main breaker.

Seems to me a better solution would be to request a larger single phase power supply or 3 phase (but not sure either available here).

Is my reasoning correct?

If I was able obtain a larger single phase supply from PEA, am I correct in assuming the only added expenses would be a new meter, and heavier wire going from meter to my breaker box?

If 3 phase was available, would I also need a new breaker box in addition to the above? Any other considerations?

I want to arm myself with as much knowledge as I can before visiting the PEA.

[Crossy]

22 minutes ago, bprhodes said:

Is my reasoning correct?

 

Sort of.

 

Firstly, a 15/45 is the largest supply PEA will normally do in rural areas. If the PEA infrastructure isn't up to it a bigger meter will do nothing to help.

 

Before jumping all over PEA you need to check whether the volt drop is their problem or yours.

 

With an assistant to operate a nice big load (hob, water heater etc.) check the voltage at your meter, they're not often sealed but even if it is there's usually a way to access copper. Check the voltage off load and then with a known load. If you drop more than 10% at 20A (5kW) or so then you may have a case.

 

Do the same check at the incoming terminals of your main breaker.

 

Report your results here.

 

Whilst an AVR may be seen as a band aid (and they are really) they do solve the issue locally without dealing with the authority whose usual response is "you have electric, no problem".

 

200V is less than 10% drop from 220V, if your pump is in trouble at that level you may have another issue.

[bprhodes]

 

Firstly, a 15/45 is the largest supply PEA will normally do in rural areas. If the PEA infrastructure isn't up to it a bigger meter will do nothing to help.
 

I live in Muang Chiang Mai, so there is hope for a larger supply.

I live alone, so getting an assistant is problematic. I have a PT girlfriend, but she would be useless and I’m not ready to fry her yet.....I will try to get the electrician who wired my house out here, he’s pretty good, and therefore understandably very busy. I will report back.

Thanks for the info!

[bankruatsteve]

44 minutes ago, bprhodes said:

I live in Muang Chiang Mai, so there is hope for a larger supply.

A 30/100 amp meter is the largest capacity meter.  A 15/45 is all you need unless you are routinely drawing more than 45amps.  The supply is the same for both.  The measurements Crossy suggested will determine whether you have a supply issue or an internal (your wiring) issue.

[bprhodes]

A 30/100 amp meter is the largest capacity meter.  A 15/45 is all you need unless you are routinely drawing more than 45amps.  The supply is the same for both.  The measurements Crossy suggested will determine whether you have a supply issue or an internal (your wiring) issue.

Some back-of-the envelope calculations suggest I would have difficulty exceeding 45 amps....until the water heaters get turned on. I have 3 heaters, including one under the kitchen sink. If someone is taking a shower and another doing dishes, with my big AC on, I would easily exceed 45 amps. I don’t want to have to go around turning off guest’s AC because I want to take a shower or do dishes. I want to have the power there when I need/want it.

Having said that, the problems I’m having (voltage drops more than 10% causing the overload on my pool pump to cycle on-off) are occurring with loads of 20 amps or less.

This suggests that either PEA can’t supply 45 amps to my meter (at least at certain times of the day), or I have a problem post-meter (maybe too much resistance between meter and house?). My electrician will come tomorrow, hopefully he doesn’t tell me “you have electricity, no problem”! I will report back.

[Crossy]

To give you something to compare to. We are on a 15/45 single-phase, typical village setup.

 

About 160m from transformer to meter then 50m of 16mm² copper between the meter and our board.

 

Measured supply impedance is about 0.5 ohms at the board (I've never checked at the meter but 100m [out and back] of 16mm² copper is about 0.115 ohms). That's 1V of drop for every 2A of load, so at least in theory, full load of 45A would drop us to 197.5V.

 

Our problem is that in the evenings the "off load" (in reality about 4A) voltage is already down to 200V and can only head downwards from there.

 

Despite everything except the water heaters (1x8kW, 1x6kw, 1x 3.5kW) being on our AVR we've never opened the incoming 63A breaker, the biggest supply current I've logged is about 65A for a minute or two (we have a mains quality monitor, 2 readings per second).

 

Note:- We cook on gas or charcoal, no hob to suck the amps.

 

EDIT 1PM, holiday monday, incoming supply 200V @ 10A load ????

 

[bprhodes]

Electrician came out and measured my voltage. With no load voltage was 223. I turned on only only 2 air cons (about 2800 watts/13amps total) nothing else significant turned on. Voltage before meter dropped 10% to about 200 V. This drop was within a volt or 2 of being the same inside the house. So there is nothing wrong inside the house, my electrician said I have to go complain to PEA that they are not supplying sufficient power to my meter.

We took photos of the voltage meter and I will go to PEA tomorrow.

My electrician said that only 15/45 is available at my pole. But down the street they might have 3 phase.

[Crossy]

Now your fun will start, but at least you know the issue lies with PEA.

 

A larger meter (even if available) won't help unless the PEA cables / transformer are upgraded.

 

Do keep us informed of your discussions.

[bprhodes]

Yes, my Thai language ability will be tested. My gf speak perfect English but is useless for anything more technical than using her phone. I will post outcome.

[bprhodes]

Visited PEA today. I filled out a service request form. They said they will call me. So now I wait....Everyone was friendly and helpful, and they’re attitude suggested they agreed that my voltage drop was a problem. I’ll report back if anything happens.

[farmerjo]

I'm in Khon Kaen province with normally low supply because of length of cable run from meter to house.

I have a variac designated for the bore pump with does the job.

It stopped working a week ago dropping to 100 volts,after convincing the Mrs to ring the PEA they came out and investigated.As always told on the phone before they arrived our problem,cable to long.

I don't understand Thai that well but picked up about worn bushings on village 30kva transformer.

Next day power was turned off then back on and bingo.The PEA maintenance guys were great and up front with the problem as not the 1st time. 

The hard part was getting the Mrs to ring as the rest of village just put up with it thinking it's normal Thai power.

[niebla]

Just called the PEA. Low power for two days now north of Meechok. They are aware of the problem. Power for fans but no AC, and the water pump is not happy. Solar does not kick in as the power is not completely out. 

[bprhodes]

Just called the PEA. Low power for two days now north of Meechok. They are aware of the problem. Power for fans but no AC, and the water pump is not happy. Solar does not kick in as the power is not completely out. 

I have very little power. To use my coffee maker I had to turn off all pumps and ACs. Just the coffee maker alone caused a voltage drop of 10v. Still waiting for PEA to call me.

[niebla]

Day three. They say they will come today. No one yet. It seems lime we are able to access 1Kw but no more.