Some questions

[Canada]

Hi there, 

I'll admit first that I havent done a search in this forum for my answers. 

I'll try to be brief

We live about 700 m outside the village. We had PEA pull cable to our house at a significant cost. The voltage seems to be not enough. ie - shower with hot water and fan speed goes down, turn on espresso maker and fan speed goes down, 2 hp submersible wont run properly without a step up transformer.
Now I want to connect 2 -18,000 BTU air cons for night time use only. 
PEA says that everything would be better if I had them pull another 2 wires our for 3 phase. That is also at significant cost. 


Would 3 phase actually supply more power? 
Would my 2 hp sub pump run properly if i dedicated a line to that?

Could I buy a 100 amp step up transformer / AVS and have that fix my problems? Or am I looking at a multi facet solution? 

I bought a volt meter yesterday and at my mains in my power room I have 204 V. In the house I have 204 V. At the end of my extension cable to the step up transformer for my 2 hp submersible, I have 190 V - so considerable voltage drop there which could be rectified by proper sized wire I think. 

My main concern is installation of my 2 air cons. 

Questions?

Answers?

 

Thanks

 

[shaggy28303]

Hey bud I had a new house built 5 years ago and had some of your problems 11K baht later all was solved due too the contractor went cheap on the house wiring. get a electrician over to your place and have him check from the power pole to your breaker box to stat goodluck

[Crossy]

Well you certainly seem to have a volt drop problem.

 

700m is a fairly long run at 220V so you should be looking at some pretty big wire, say 75mm² or bigger, do you have any idea what was installed?

 

What is the incoming supply voltage off-load (open the main breaker and check the input)? If it's low then ask PEA if they can move you to another phase or possibly change the tap on the transformer to give a bit more headroom.

 

Otherwise you're looking at an AVR (automatic voltage regulator) which is indeed a transformer, it adjusts itself to keep the output constant. There are several treads about them, so try a forum search.

 

Installing 3-phase will give you more power in total, but you won't get any more juice per-phase, you can however spread the load around somewhat.

 

 

[bankruatsteve]

Sounds like your PEA isn't being especially supportive to your needs.  Yes, 3-phase would help but likely to be 3 phases at 204v.  Getting a transformer closer to your house would be best but the only? other solution is a giant and expensive AVR.  You might try crying to the PEA since you already bought them a lot of wire.

[Canada]

I've checked the wire down the pole and to our house. Its all 25 sq.mm.

So looks like its a 700 m run of 25 sq mm. 

open breaker right now at low usage time is 227 volts. switch on 2 hp submersible and volts at main breaker drop to 207. That's running the pump through a smaller step up transformer, not direct.

 

 

[Canada]

Im guessing pole to house isnt a big issue because its only about a 50 m run. It's the PEA supply line that's the problem. So' I've fallen victim to the ways of Thailand. I get that.

Anyone have any luck taking PEA to task on something like this? I'm not an electrician so I dont really know enough to do that effectively. I dont lack in assertiveness though but there is a fine line here between assertiveness and perceived aggression. Thais are pretty sensitive. 

[Canada]

1 hour ago, bankruatsteve said:

Sounds like your PEA isn't being especially supportive to your needs.  Yes, 3-phase would help but likely to be 3 phases at 204v.  Getting a transformer closer to your house would be best but the only? other solution is a giant and expensive AVR.  You might try crying to the PEA since you already bought them a lot of wire.

I can get a 20 Kva AVS for about 23000 baht at Global

[Canada]

Then I guess the next question is will I be able to power 2 air cons through my 20 KVA AVS ? 

[Crossy]

That 20kVA unit will happily provide nearly 100A

 

It will run your whole house without issue, the only problem is just how low it pulls the PEA supply.

 

EDIT If I've done the sums correctly about 25A will pull your incoming supply down to 150V (where the AVR will start to run out of steam). You should be OK with the two aircons but I wouldn't want to bet on the water pump and any water heater at the same time.

 

EDIT 2 The volt drop does seem to be in line with PEA providing 25mm2 all the way

[Canada]

14 minutes ago, Crossy said:

That 20kVA unit will happily provide nearly 100A

 

It will run your whole house without issue, the only problem is just how low it pulls the PEA supply.

 

EDIT If I've done the sums correctly about 25A will pull your incoming supply down to 150V (where the AVR will start to run out of steam). You should be OK with the two aircons but I wouldn't want to bet on the water pump and any water heater at the same time.

 

EDIT 2 The volt drop does seem to be in line with PEA providing 25mm2 all the way

OK. Thanks for doing that for me.

 

Could you explain a little for me please?

 

I can see the figures for watts- 1450, amps -(6.8) and voltage. (220-240)But I dont quite understand the relationship of everything. I think I do, but I clearly dont when you look at how I understand it (below) and your comment that running air should be okay, but not much more than that 

 

2x1450 is say 3000 watts of an available 20000 correct? apply a factor of.8 to the 20 leaves me with 16 kw of which I've used 3 for air. I should still have 13 kw available shouldnt I?

 

I'm confused

[Canada]

Chances of running the 2 airs, the pump, espresso, and having a hot shower all at the same time are pretty slim. We could manage ourselves to make sure that that never happened.
Airs are nighttime only. I would like to run the pump as well because line requirements are less in the village at night and we run drip tape on a few rai of cane in our backyard. I'd prefer to water at night. 

 

[Crossy]

8 minutes ago, Canada said:

2x1450 is say 3000 watts of an available 20000 correct? apply a factor of.8 to the 20 leaves me with 16 kw of which I've used 3 for air. I should still have 13 kw available shouldnt I?

 

For the AVR, yes, no issue whatever.

 

The problem is that every Amp you pull from the AVR at 220V will pull about 1.5A from the supply (if it's down to 150V).

 

You have about 3 Ohms of round trip resistance (from your experiment with the 2HP pump and the volt drop), so you lose 4.5V for every Amp you pull from the AVR output. To pull your off-load 227V down to 150V needs about 25A.

 

This is a quick-and-dirty guesstimate of worst-case, but if you don't score with PEA ...

 

EDIT Air only at night, running on a 30% duty-cycle (assuming they're not massively under/over sized) I reckon you'll be fine with the pump as well.

 

[Canada]

3 minutes ago, Crossy said:

 

For the AVR, yes, no issue whatever.

 

The problem is that every Amp you pull from the AVR at 220V will pull about 1.5A from the supply (if it's down to 150V).

 

You have about 3 Ohms of round trip resistance (from your experiment with the 2HP pump and the volt drop), so you lose 4.5V for every Amp you pull from the AVR output. To pull your off-load 227V down to 150V needs about 25A.

 

This is a quick-and-dirty guesstimate of worst-case, but if you don't score with PEA ...

 

EDIT Air only at night, running on a 30% duty-cycle (assuming they're not massively under/over sized) I reckon you'll be fine with the pump as well.

 

OK. Well I'm going to trust you on this. I'll buy the AVS and install the 2 airs. I can modify my water requirements pretty easily. 

I think I'll retain more serenity going this way vs. taking PEA to task, or getting them to pull 2 more wires that will be undersized that i still wont own. 

Note. The 2 airs will be overkill for the rooms they are going in. 12 sq m each. But the load will be pretty good because the rooms are upstairs. Terrible hot. We cannot sleep upstairs right now. 

So then if I modify my water requirements, I should be able to by a smaller AVS. Correct? 10 KVA should cover the 2 airs OR the pump 

[Crossy]

4 minutes ago, Canada said:

So then if I modify my water requirements, I should be able to by a smaller AVS. Correct? 10 KVA should cover the 2 airs OR the pump 

 

Don't push the envelope. I wouldn't go below a 15kVA AVR to be honest.

 

Is it significantly cheaper than the 20 KVA unit?

[Canada]

2 minutes ago, Crossy said:

 

Don't push the envelope. I wouldn't go below a 15kVA AVR to be honest.

 

Is it significantly cheaper than the 20 KVA unit?

No, not worth causing myself problems. :)

Thanks again for your help. I'll report back and let you know how it all goes. 

[Wirejerker]

Just a query. Where is your kWh meter? On your pole or 700 meters away


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[Canada]

22 hours ago, Wirejerker said:

Just a query. Where is your kWh meter? On your pole or 700 meters away


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The meter is on the pole. Why do you ask?

[Wirejerker]

That's good it's the answer I expected. If your meter was 700 meters away you would be paying for the electricity consumed in those wires. So your fine.


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[Canada]

Have installed the 20 KVA AVS. Works as I thought it would. I've yet to run both air cons off it tho as the brain in one is pooched. Waiting for parts. 

 

I'm going to have some solar related questions combined with Inverter Air Cons. This thread-or a new one?

I'll search a few other threads first. 

 

 

[Crossy]

1 minute ago, Canada said:

I'm going to have some solar related questions combined with Inverter Air Cons. This thread-or a new one?

 

New thread I suggest.

 

It would be interesting to know how low the input voltage to the AVR goes when the A/C is running.

[Canada]

7 hours ago, Crossy said:

 

New thread I suggest.

 

It would be interesting to know how low the input voltage to the AVR goes when the A/C is running.

Well, I ran a 2 HP submersed pump, 6000 watt water heater, on demand water pump, some fans and a couple of lights all at once. The voltage was down to 150 on the input side, 220 output and AVS at 90% capacity. I havent checked just the air yet. 

[Canada]

Just went and checked for you. Air, tv, couple of lights and fans-about 20 amp draw. Input at about 205. Output 240.