Mr Sundara I provide the information to help the needy fellow members . 

please find the diagram. Hope this helps.

 A good source would be read through the following literature.

A. Abur and F. H. Magnago, “Optimal meter placement for maintaining observability during single branch outages,” IEEE Trans. Power Syst., vol. 14, no. 4, pp. 1273–1278, Nov. 1999.

Secondly placing multiple PMU's has a cost implication with respect to optimal phasor measurements.. Placing a PMU on all the substations permit measurements of the state of the network. 

Geographical factors would indicate whether proper communication infrastructure is available or not. GPS signal may be used for timing and synchronizing the PMU.

Your questions seems to be unclear.  

One has to follow optimal placement measures of the PMU to observer the network in complete. Normally integer programming methods or heuristic search methods may be used to find the most best placement.

Geographical location is important to determine the availability of networks( communications) to transmit the information. GPS time stamping helps but derations could happen due to climatic conditions .So a careful selection of time stamping methods as well as communication methods needs to be chosen. 

Yes. I understand how the PMUs have to be placed for better communication. I want to know the how the PMU is connected to a bus? Meaning literally. A picture might help. To explain more, the PMU device is connected to a bus through a current transformer and a voltage transformer if I am right. Otherwise how? Is it clear now?

Mr Sundara I provide the information to help the needy fellow members . 

please find the diagram. Hope this helps.

Thanks a lot Deepak..

PMU can be installed through CT or PT with network bus where measurenet to be done. If the area is fissible for installation of PT or CT, PMU can be installed there.

https://www.researchgate.net/publication/310006226_GAMS_Code_for_Optimal_PMU_Placement

Code GAMS Code for Optimal PMU Placement