Home Electrical Installation

[bcross2001]

Our home is about ready - but we now have discovered that the 230V power coming from the road (approximately .6 K away) is only 221V at our home and there is not enough current to properly run our electrical appliances.

The local power company suggested installing a 30KV transformer (19Kv primary 230V secondary-single phase) at the road in order to keep the voltage and current constant at 230V.

Does this sound like the proper solution?

The electrical wire which runs approximately .6 Kilometer to our home is rated at 750V 131 Amps.

Barry

[Crossy]

You should worry, our incoming supply in Delhi is about 190V

Thailand is nominally 220V 50Hz, 210-230 is reasonable.

Did you check the supply on-load? (ie with stuff turned on)

What appliances don't run properly?

Is there already a transformer at the road, how many other houses are connected to it?

It would also be useful to know what your prospective load was calculated at (or how big your house is).

Edited June 1, 2007 by Crossy

[bcross2001]

You should worry, our incoming supply in Delhi is about 190V

Thailand is nominally 220V 50Hz, 210-230 is reasonable.

Did you check the supply on-load? (ie with stuff turned on)

What appliances don't run properly?

Is there already a transformer at the road, how many other houses are connected to it?

It would also be useful to know what your prospective load was calculated at (or how big your house is).

Hello Crossy

I'll take these one at a time.

We have not turned on everything as the electrician is afraid that we might cook something at present. We have three 36,000Btu Trane a/c units, 2 9,000Btu a/c units, oven, dish washer, frig, freezer, cooler, 300 ltr hot water heater plus all the extra's well pump, tv's computers, lights etc.

Each of the 30Kv transformers on the main road are spaced about .5kilometer apart. We are at the very end of one of these connections with about 10-20 homes between us and the transformer - after our connection there are no further transformers - we are at the end of the line.

Barry

[Crossy]

At a glance, I suggest that you're going to need your own Tx.

10 houses on a 30KVA gives you 3KVA each on average, a whole 13Amps

Are the supply chaps suggesting a Tx to yourself? (and you pay for it) if so I suggest you go for it. How much are they suggesting it will cost?

A 30KVA unit will give you a 150 Amp supply which seems a bit OTT, perhaps that's the smallest available. We manage with a 45A supply although we don't have as many A/C units (3 in total).

It really needs a proper prospective load calculation doing but you can bet that the supply chaps won't bother, they'll just guess. Do ensure that the meter they provide can handle your load.

Edited June 1, 2007 by Crossy

[technocracy]

Barry,

I am pretty much in the same situation as yourself, I also am at the end of the line getting the dregs of what power there was from the village transformer. I wouldn't worry about switching things on though, the main problem we have is the power most of the time isn't sufficient to start the compressors on the air-con so they just shut themselves off. Here we are only talking 22k btu (6500watt) units. The smaller 11k btu units, the 2200 watt water heater and 1000watt water pump work without issues.

Can you just clarify you are on single phase rather than 3 phase? The main reason I ask this is that we have been told that the smallest 3 phase transformer they can supply is 50Kw. I am trying to get clarification that this is the case and we are just being oversold - although this I doubt as they know I understand the electrical side of things and are wary of me! The company has told me that if I was on single phase I could have a 20, 25 or 30Kw Tx no worries.

Oh the cheerie side I did laugh the yesterday when I drove past a large house that is being built no that far from myself by a local Lao. He obviously has plenty of money to splash about but not much idea as he's just had a 100Kw Tx located outside his house (obviously just said give me the biggest so I can show my mates!). What he is going to do with 450amps(!) I really do not know!! Probably got a 63amp breaker in his house . .. .

[bcross2001]

At a glance, I suggest that you're going to need your own Tx.

10 houses on a 30KVA gives you 3KVA each on average, a whole 13Amps

Are the supply chaps suggesting a Tx to yourself? (and you pay for it) if so I suggest you go for it. How much are they suggesting it will cost?

A 30KVA unit will give you a 150 Amp supply which seems a bit OTT, perhaps that's the smallest available. We manage with a 45A supply although we don't have as many A/C units (3 in total).

It really needs a proper prospective load calculation doing but you can bet that the supply chaps won't bother, they'll just guess. Do ensure that the meter they provide can handle your load.

Crossy - I believe your right on the need for a Tx - these units are fed 19KVolts to the primary and either 230/460 output on the secondary.

Given the .6 Kilometer run to our home and the normal voltage drop associated with the power line this option we feel is the best.

Pricing I'm told runs around 30K Baht per unit plus installation.

I check on the meter issue.

[bcross2001]

Barry,

I am pretty much in the same situation as yourself, I also am at the end of the line getting the dregs of what power there was from the village transformer. I wouldn't worry about switching things on though, the main problem we have is the power most of the time isn't sufficient to start the compressors on the air-con so they just shut themselves off. Here we are only talking 22k btu (6500watt) units. The smaller 11k btu units, the 2200 watt water heater and 1000watt water pump work without issues.

Can you just clarify you are on single phase rather than 3 phase? The main reason I ask this is that we have been told that the smallest 3 phase transformer they can supply is 50Kw. I am trying to get clarification that this is the case and we are just being oversold - although this I doubt as they know I understand the electrical side of things and are wary of me! The company has told me that if I was on single phase I could have a 20, 25 or 30Kw Tx no worries.

Oh the cheerie side I did laugh the yesterday when I drove past a large house that is being built no that far from myself by a local Lao. He obviously has plenty of money to splash about but not much idea as he's just had a 100Kw Tx located outside his house (obviously just said give me the biggest so I can show my mates!). What he is going to do with 450amps(!) I really do not know!! Probably got a 63amp breaker in his house . .. .

technocracy - you most likely saw our reply to crossy - we are using single phase - I noted your tx sizes - given crossy's values a 20Kw would provide around 100amps and I'm sure would lower our costs - Im looking today to see if I can locate one.

Thanks for your input

Barry

[astral]

Do ensure that the meter they provide can handle your load.

It may be a silly question, but what happens if you have a 10A meter and install several A/C and run them

all at the same time?

Will it fry the meter or just blow the company fuses, if they have such things in LOS?

Just curious.

BTW My house as a 30A 3PH supply as I did not want to take chances.

[Crossy]

It may be a silly question, but what happens if you have a 10A meter and install several A/C and run them

all at the same time?

Will it fry the meter or just blow the company fuses, if they have such things in LOS?

Pretty much the case.

The sense coils in the meter are designed for a particular maximum current (the size of the wire), if you exceed that current by a significant amount (20% or so) then you run the risk of destroying the meter or at least damaging it and throwing off the calibration causing it to mis-read.

[bcross2001]

Do ensure that the meter they provide can handle your load.

It may be a silly question, but what happens if you have a 10A meter and install several A/C and run them

all at the same time?

Will it fry the meter or just blow the company fuses, if they have such things in LOS?

Just curious.

BTW My house as a 30A 3PH supply as I did not want to take chances.

Crossy

I checked with the power people today and they inform me the transformer they intend to use is 30KVa - at 65.2amps - our meter is rated at 40 amps - I have requested one to handle the 65.2amp rating of the transformer.

Many Thanks

Barry

[tpthai2]

Do ensure that the meter they provide can handle your load.

It may be a silly question, but what happens if you have a 10A meter and install several A/C and run them

all at the same time?

Will it fry the meter or just blow the company fuses, if they have such things in LOS?

Just curious.

BTW My house as a 30A 3PH supply as I did not want to take chances.

Crossy

I checked with the power people today and they inform me the transformer they intend to use is 30KVa - at 65.2amps - our meter is rated at 40 amps - I have requested one to handle the 65.2amp rating of the transformer.

Many Thanks

Barry

You might want to try this site: <http://www.siliconthai.com> I have found there products to be quite good.

Regards...