Answer: Bundling of conductor is nothing but it is the use of more than one conductor per phase. The main purpose of using bundled conductor in transmission line is to reduce corona loss and radio interface.
Single stranded conductors are used in transmission system usually up to 220 KV. But it is not possible to use single-stranded conductor for the voltage above 220 KV systems. For very high voltage system, hollow conductor can be used to optimize the flow of current through it. But erection and maintenance of hollow conductors in the ∑HV system are not economical. The problem can be solved by using bundled conductors instead of hollow conductor in the electrical transmission system above 220 KV voltage level.