how can i improve power factor in 3phase supply?

Answer 1

Shortening the length of the cables and increase the copper size will both give you some improvement. Improvement in the quality of the ground is what I would look at next. Then maybe the quality of the connections. That should get you started.
Good Luck

Answer 2

Energy losses in transmission lines increase with increasing current. Power companies therefore require that customers, especially those with large loads, maintain the power factors of their respective loads within specified limits or be subject to additional charges. Engineers are often interested in the power factor of a load as one of the factors that affect the efficiency of power transmission.

Power factor correction is achieved by complementing an inductive or a capacitive circuit with a (locally connected) reactance of opposite phase. For a typical phase lagging p.f. load, such as a large induction motor, this would consist of a capacitor bank in the form of several parallel capacitors at the power input to the device.

Instead of using a capacitor, it is possible to use an unloaded synchronous motor. This is referred to as a synchronous condenser. It is started and connected to the electrical network. It operates at full leading power factor and puts VARs onto the network as required to support a system’s voltage or to maintain the system power factor at a specified level. The condenser’s installation and operation are identical to large electric motors.

Answer 3

Use capacitor banks in case you have huge inductive loads to improve the power factor.

Answer 4

In general, motor loads are inductive and lower the power factor. To offset that, you must add capacitors to the line.

Answer 5

Decrease your motor load or start adding capacitor banks ( or the synchronous motor mentioned above). "Energy saver" motor starters which reduce the voltage across a lightly loaded motor will also help to some degree.

Answer 6

using capacitors is the only economic solution.