As known DC Link ( HVDC Transmission Line) is more efficient , less loss in power consumption, Why is it not used in short Transmission Lines ?

For short distances, HVDC transmission is not economical. The cost of converter stations at the generation and distribution end will be very high. Hence, it is used only in long transmission lines (for example, more than 500km).

Maintenance cost and riskiness in handling

Because AC current has a second polarity of The Changing Of The Highest Polarity The Polarity Up Low. while the DC current has a positive polarity of Yang Fixed namely, zero and negative.

It is not used in short transmission lines because of economic and technical reason. It need a costly HV inverter and converters, also requiring an advances and very expensive technology.

In any engineering project cost of the project plays important role.The cost decides whether the project will be carried out or not. Same is the case in the field of electrical engineering. In short distances transmission system, the cost of HVDC is more as compared to HVAC, the equipments used e.g Converters and other accessories are more costly . And thier maintenance is very essiential. For that reason HVDC is not applicable in short Transmission network.

It is more difficult to transform DC voltage.

As we know for short transmission purposes AC transmission is use, not the DC one. The reason is that HVDC generation and transmission cost is too high and it is economical only for long transmission lines. In case of long transmission lines HVDC transmission is more economic then HVAC. But in short one AC transmission is more economic. So here we have concerned with the economic transmission.