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BANGKOK 25 June 2019 01:17
bprhodes

Low Voltage in Chiang Mai

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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.

 

 

 

 

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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.

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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?

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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.

 

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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!

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

 

 

 

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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)?

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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. 

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What you need is.....

 

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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

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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 🙂

 

 

 

 

 

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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.

 

 

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For interest.

 

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

 

Untitled-1.jpg.acc8137fa0609ad3623c43eeea01a85b.jpg

 

 

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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)?

 

 

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Posted (edited)

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 by opensea

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