identification of connections

Hello all,

How can we identify the star and delta connections? Now I have the winding coils which is sealed in a pack appearing only three phase wires out. How to know if it is star connected or delta connected? Could you please tell me?

Thank you

If Star connection is made, total inductance value will be 2 times of each one between two terminals.If Delta connection is made, the inductance will be lower than single one between any two terminals.
You can check it with a simple Inductance Meter

Hi,

I'm just assuming that you talk about a motor. 3 phase AC asynchronous?

If so:
There is no need to care about internal star or delta connection.
Just connect the motor. Apply the voltage given on the datasheet and it will run according datasheet.

Only if there are 6 wires, then you have to take care how you have to connect them.

If you have one motor with star connection rated 1hp on 400V AC..
And if you have a different motor, also rated with 1hp on 400V AC, but internally wired in delta connection...
I doubt you will recognize any difference. Neither with RPM, torque, nor with inductance and amperes...
For sure internally, at the coils, there is a difference.

*****
Example with ohmic resistors.
Let's assume you have a 3kW three phase heater for 400V
If it is connected in star style, then each heating element needs to have 53.33 Ohms
In delta connected each heating element needs to have 160 Ohms.

Now imagine you use a ohmmeter on the star connected 53.33 Ohms --> you will measure 106.67 Ohms between two wires.
Now imagine you measure the 160 Ohms in delta connection: --> you will again see 160,67 Ohms.
--> you can't measure the difference from outside, and it will generate the same heat.

Klaus

For every star circuit there's an equivalent delta circuit and vice versa. https://en.wikipedia.org/wiki/Y-Δ_transform

If it's a black box, you can't identify if the internal circuit is star or delta connected, and you don't need to.

Madbunny1 said:

How can we identify the star and delta connections? Now I have the winding coils which is sealed in a pack appearing only three phase wires out. How to know if it is star connected or delta connected?

Click to expand...

If connected as a star, you will have 4 wires coming out of the box (one of them, typically coloured black, will be the star point).

If connected as delta, you will have 3 wires coming out and they will be differently coloured (all are phases and there will be no neutral point).