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At the end of the section, you should be able to:
At the end of the section, you should be able to:
Explain the concept of power factor.
Explain why power factor needs to be corrected.
Explain how power factor can be corrected and determine the required capacitance to do so.
Recap of Power triangle
Recap of Power triangle
Summary of power triangle
Summary of power triangle
Power factor
Power factor
As only real power is useful, it is important to quantify it as a ratio of the apparent power. The "ratio" is defined as the power factor.
As only real power is useful, it is important to quantify it as a ratio of the apparent power. The "ratio" is defined as the power factor.
However, while power factor is a numerical figure, it can be leading or lagging depending on the nature of the load.
However, while power factor is a numerical figure, it can be leading or lagging depending on the nature of the load.
Summary
Summary
An example
An example
Power factor effect
Power factor effect
An analogy
An analogy
A simple analogy of the concept of power factor is that of a cappuccino. The coffee mug must have sufficient capacity to contain both the coffee and froth, corresponding to the apparent power (i.e. total power). The froth represents the reactive power and the coffee represents the real power. The "real" value we derive is only from the coffee. As the froth is not contributing significant value, reducing it may make your cappuccino more value-for-money.
A simple analogy of the concept of power factor is that of a cappuccino. The coffee mug must have sufficient capacity to contain both the coffee and froth, corresponding to the apparent power (i.e. total power). The froth represents the reactive power and the coffee represents the real power. The "real" value we derive is only from the coffee. As the froth is not contributing significant value, reducing it may make your cappuccino more value-for-money.
Reducing the reactive power will translate to a lower apparent power required (for the same real power output) and hence, a lower supply current. For the same real power output, a lower apparent power requirement will mean a higher power factor. This is known as power factor correction.
Reducing the reactive power will translate to a lower apparent power required (for the same real power output) and hence, a lower supply current. For the same real power output, a lower apparent power requirement will mean a higher power factor. This is known as power factor correction.
Summary video for the concept of power factor and introduction to power factor correction
Summary video for the concept of power factor and introduction to power factor correction
Power factor correction
Power factor correction
An example ...
An example ...
A small factory has a 25 kW resistive load and a 40 kVA inductive load of lagging power factor of 0.6. If the supply is 850 V at 50 Hz, determine the capacitive element required to raise the overall power factor to 0.95. Calculate the original and new supply current and compare the values.
A small factory has a 25 kW resistive load and a 40 kVA inductive load of lagging power factor of 0.6. If the supply is 850 V at 50 Hz, determine the capacitive element required to raise the overall power factor to 0.95. Calculate the original and new supply current and compare the values.
Give it a try before referring to the solution video.
Check your understanding 7
Check your understanding 7
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