How to wiring the transformer

[olaychang]

Dear sir,
Please kindly help me to check the wiring of this transformer
Thanks!

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[Akita]

The turn ratio will give you the answer.

40:4:1

x2 = 80:8:2
x3 = 120:12:3
...
x6 = 240:24:6

So, if your input Voltage is 120Vac (connected to pin 1&2) then you will get 12Vac on pin 4&5, and 3Vac at pin 6&7

If your input Vac is 240Vac(connect pin 1&2) and then you will get 24Vac on pin 4&5, and 6Vac at pin 6&7

If you use Pin1&3 turn ratio should be 185:4:2

 

[olaychang]

but, 6&7 is short,
how can I measre the level from 6&7?

 

[Akita]

Basically all set of winding are shorted, but when you measure it with DMM it will create a resistance. But pin 6&7 winding is too little compare with 4&5 or 123, so the created resistance is very low, your multimeter may assume that it is shorted.

 

[Akita]

Sorry,..A little bit correction here
If you use Pin1&3 turn ratio should be 185:4:1

 

[simon5]

How do you get that 185 number between pin 1 and 3 ?

 

[Akita]

From the picture;

The ratio is 40:4:1
40 is for pin 1&2, 4 is for pin 4&5 and 1 is for pin6&7

At the working voltages
Pin1&2 is 78v, Pin 1,2&3 is 370v.

Because of some winding resistance the voltage will drop a bit from 80v to 78v. So, the ratio is (78:7.8:2 ) / 2 = 39:3.9:1
This is almost same as the given ratio 40:4:1

If you connect to pin 1&3, it will become 370v:7.8:2. After divided by 2 = 185:3.9:1

To make it easier to read, It will be 185:4:1

 

[simon5]

Thank you very much for your good explanation, I was curious.

It seemed simple, but couldn't find how to get it. 🙂