Question

Suppose you have a motor with a power factor significantly less than 1. Explain why it would be better to improve the power factor as a method of improving the motor’s output, rather than to increase the voltage input.

a) Improving power factor directly enhances motor efficiency.

b) Increasing voltage input does not affect motor power factor.

c) Power factor has no impact on motor output.

d) Increasing voltage input only increases power consumption, not output.

Answer 1

Improving the power factor of a motor increases its efficiency by reducing wasted energy from reactive power and is more effective than increasing voltage input, which can create additional losses without improving output.

Step-by-step explanation:

If we have a motor with a power factor significantly less than 1, improving the power factor is a better method of boosting the motor's output than increasing the voltage input. The reason for this is twofold:

• Direct Enhancement of Efficiency: Improving the power factor of a motor directly affects its efficiency because it reduces the phase difference between voltage and current, leading to less wasted energy in the form of reactive power and therefore more effective use of the electrical power.
• Independent of Voltage Input: Increasing the voltage input to the motor does not change the power factor. Although higher voltages can lead to greater current and more power being delivered, this doesn't necessarily translate into increased motor output due to losses from heat and a potential mismatch between the motor's operating voltage and the increased input.

Additionally, electric motors already have a high efficiency; for example, a 100-hp motor might have an efficiency of 90%, and a 1-hp motor around 80%. Enhancing the power factor contributes further to this efficiency without necessitating other changes to the motor's electrical supply.