Final answer:
The most effective method of power factor correction often involves adding capacitors to the circuit, which improves the efficiency of a motor with a low power factor, making it a better solution than merely increasing the voltage input.
Step-by-step explanation:
The question is asking for the most effective method of power factor correction within electrical installations. When dealing with a motor that has a power factor significantly less than 1, it is better to improve the power factor as a method of increasing the motor's output efficiency, rather than simply increasing the voltage input. The power factor, given by cosφ, represents the ratio between the real power that does work and the apparent power that is drawn from the power source, and ranges from 0 to 1. A power factor of 1 indicates that all the power is being efficiently used to do work.
To correct a poor power factor, capacitors are typically added to the circuit, because they provide leading reactive power which can cancel the lagging reactive power of inductive loads, thus improving the power factor and overall efficiency of the motor. This is preferable over just increasing the voltage input, which does not directly address the inefficiency and could lead to additional electrical losses or even damage to the motor and infrastructure.