Since, the three phase windings generate the required rotating torque, a three-phase motor does not require a capacitor in order to function properly.
On the other end, big motors with a horsepower rating of 5 or more tend to have a low power factor load, hence it is common practise to connect power factor correction capacitors across their terminals in order to increase it to an acceptable level.
On that point, three-phase capacitor banks are linked (connected) in parallel with the induction motors so that the power factor may be corrected. In the vast majority of conditions, capacitor banks are either linked across the supply itself, (or) switching of motor & capacitor bank connections will take place simultaneously.
In addition, a capacitor may be included into the circuit of a three-phase motor in order to boost the performance of the motor’s starting phase, lower the amount of energy used for starting, & improve the motor’s overall efficiency. However, the specific value of the capacitor that is required for a three-phase motor will vary depending on a number of factors. These factors include the horsepower of the motor, the voltage rating of the motor, and whether the motor has multiple speeds.
It is advised that the specifications provided by the motor’s manufacturer be consulted or that a skilled electrician be contacted in order to establish the suitable capacitor value for a 3-phase motor. They are able to determine the necessary capacitance by using the specifications of the motor in conjunction with the needs of the particular application. If employ a capacitor with the wrong value, it will risk the motor not functioning properly, overheating, or even being damaged.