Transformers Undersized.

[malcolminthemiddle]

We suspect the transformers installed in our Moo Baan by the Developer are undersized and could result in outages once the development is complete. How do we check in a way that provides tangible evidence? Thanks in advance.

[Delight]

I do not think that the transformers are the responsibility of the Developer -beyond creating a facility to support them somewhere.

To my knowlege -admit that it is not complete- they are supplied by the power company.

The Moo baan will simply give a deposit to the power supplier.

Some years ago birds entered the transformer on my building and destroyed them.

The building insurance picked up the bill

As far as performance -you have not stated the basis for your claim -i.e undersized

However I think that you should contact your power supplier

 

[moe666]

Transformer here are all smaller than what you would see in the US as the Thais use a higher voltage and lower amperage system. Just drive around and you will see the difference in size of transformers

[janclaes47]

6 hours ago, malcolminthemiddle said:

How do we check in a way that provides tangible evidence?

You could start with posting how many houses and average size of house, and the capacity of the transformers, and I'm sure @Crossywill make the calculation for you

 

49 minutes ago, Delight said:

I do not think that the transformers are the responsibility of the Developer

Of course the developer is responsible since he has to pay for the transformer. PEA doesn't install anything for free. In addition, after the developer has paid for it he has to transfer them to PEA, so that they can connect other customers as well.

[Crossy]

As well as the developement size please let us know the following:-

• The rating of the transformer(s) currently installed (take photos of the rating plates).
• The meter size which is being used (15/45 or 30/100).
• Do the homes have single or 3-phase supplies?

Take this information along to your local PEA office and ask the opinion of their engineers.

 

Meanwhile I'll ask someone who likely knows. Sizing transformers for domestic supplies is something of a black-art, it's not as easy as adding up all the meter sizes. I will say that it comes out a lot smaller than most people would imagine.

 

[malcolminthemiddle]

Thanks to everyone for their replies.

 

Some more information.

 

1. There are 63 villas of varying sizes in the Moo Baan.

2. The average full load requirement per villa is 165,000 watts.

3. The house meter size is 15(45)A.

4. Each villa has a 3 phase supply.

5. Each villa has a minimum 5kW solar panel system (some villas have up to 25 kW).

6. Currently there are 2 transformers installed for the whole project each with a capacity of 250 kVA (see pic).

7. The transformers are located inside the Moo Baan on land designated as "common".

 

Regarding future ownership I understand that the transformers, which were purchased by the Developer and installed by the PEA, become "common property" of the Moo Baan once the development is finished and handed over to the residents. Any cost of transformer maintenance/repair will be according to PEA terms and conditions. The residents can insist only residential and common meters inside the perimeter of the Moo Baan are connected to the transformers. Hence the importance of confirming the transformers are sufficiently sized before the development is handed over to the residents

 

 

[janclaes47]

21 minutes ago, malcolminthemiddle said:

2. The average full load requirement per villa is 165,000 watts.

Could that be a mistake, as it accounts to 434 Ampere on a 3phase power supply?

 

Edit : Think It's me who made a mistake by using wrong power factor

Edited November 11, 2018 by janclaes47

[Crossy]

On 11/11/2018 at 11:03 AM, malcolminthemiddle said:

1. There are 63 villas of varying sizes in the Moo Baan.

2. The average full load requirement per villa is 165,000 watts.

3. The house meter size is 15(45)A.

4. Each villa has a 3 phase supply.

5. Each villa has a minimum 5kW solar panel system (some villas have up to 25 kW).

6. Currently there are 2 transformers installed for the whole project each with a capacity of 250 kVA (see pic).

7. The transformers are located inside the Moo Baan on land designated as "common".

 

2. See answer 3, where did this number come from? (equates to >250A per phase). I'm assuming someone just added up the installed breaker ratings.

3. A 15/45 3-phase will max out at 30,000 W (30kW)

 

5. I'm assuming that these are grid-tie systems. A minimum of 65*5kW=325kW being pushed into the system.

6. 2 x 250kVA = 500kVA / 63 = 8kVA per villa on average. Maybe not too bad when combined with 5.

 

Let me feed this to my "clever person".

 

I'm assuming that PEA have been in on the design, particularly with the amount of installed solar.

 

 

[malcolminthemiddle]

31 minutes ago, Crossy said:

 

2. See answer 3, where did this number come from? (equates to >250A per phase). I'm assuming someone just added up the installed breaker ratings.

3. A 15/45 3-phase will max out at 30,000 W (30kW)

 

5. I'm assuming that these are grid-tie systems. A minimum of 65*5kW=325kW being pushed into the system.

6. 2 x 250kVA = 500kVA / 63 = 8kVA per villa on average. Maybe not too bad when combined with 5.

 

Let me feed this to my "clever person".

 

I'm assuming that PEA have been in on the design, particularly with the amount of installed solar.

 

 

2. Correct. 165,000 watts is the sum total taken from the load schedule (see attached pic).

3. For confirmation of 15/45 see attached pic of meter.

5. The solar systems are tied into the grid.

 

Assume the PEA design and quote for 2 x 250 kVA transformers was made without consideration for solar.

[Crossy]

Confirmed 3 x 63A main breakers, so we have 63*220*3 = 41.5kVA max per villa despite what the adding up says. Diversity is your friend.

 

 

[Crossy]

7 hours ago, malcolminthemiddle said:

Assume the PEA design and quote for 2 x 250 kVA transformers was made without consideration for solar.

The solar, being on the load side of the transformers should help matters.

 

I may be mistaken, but it's my understanding that any solar over 10kW classes as "industrial" and has a whole new set of rules. PEA definitely need to be in on the act if they're not already.

[Crossy]

Well, after discussion with those more knowledgeable the conclusion is that 500kVA for 63 houses should be fine (it's 4 times what would be allowed for in the UK), particularly with the addition of the solar.

 

Of course TiT...

 

[malcolminthemiddle]

7 hours ago, Crossy said:

Well, after discussion with those more knowledgeable the conclusion is that 500kVA for 63 houses should be fine (it's 4 times what would be allowed for in the UK), particularly with the addition of the solar.

 

Of course TiT...

 

Many thanks