What is virtual ground in power supply? Can anybody explain me about using virtual ground in delta connection?

 

I'm guessing you are referring to the neutral point in a 3-phase delta connection [such as in a 3-phase transformer delta connected winding] in a power supply/distribution system.

Is that what your question relates to?

 

If you are talking about DC power supplies, you can use a power opamp to "split" a single DC output into two supplies. The output of the opamp maintains a "virtual ground". The supply return/ground becomes the negative voltage.

From National Semiconductors LM675 datasheet:

If desired, you could replace the two 22k resistors with a 50k pot; then you could vary the ratio between the upper and lower voltages. I'd put a small cap from the pot's wiper to ground as well; less noise on the reference voltage for the ground.

 

My input is AC only. am asking what tnk has told

 

3 phase delta is typically an 'ungrounded', or floating supply. If you choose, you could reference any one lead to ground. Care should be taken however, in that a contrary reference hasn't been made elsewhere, or if your using a split/high line arrangement.

 

I understand that the virtual ground is an "ungrounded" node in a circuit that is at 0 V potential. It is more widely used in op-amp circuit analysis.