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Power factor:- I bet there is no better way to explain it.

Nice anecdote to explain PF POWER FACTOR in electricity. 


Equate electricity to a moving car.

The resistance in the circuit is the car driving on a level road.

Creating an upward slope / gradient equates to creating inductance of the circuit . The more inductance added, the higher the gradient, so we need more energy to move the same car – but we are not going faster or getting any benefit from this addition – it is just the nature of the load which causes this uphill. Windings/coils like motors/transformers are inductive loads.#3

As we are, we wanted to find a way to combat this phenomena and found it in capacitors. Capacitance creates downslopes / downhills causing our car to want to run away, not adding any value to our electrical energy – in fact we have to brake it now.

Adding both (inductance/capacitance) in the right proportions keeps the car on the straight, thereby ensuring the maximum use/efficiency of electrical energy. That’s a nice idea to save money.

Question: What will happen if too much capacitance gets added?

Yes, you are right, it will swing the PF from positive to negative which is even worse – the caps will not last for sure!


Foot notes:

#1:And whats up with the name: POWER FACTOR? The ratio of the actual work achieved (real power) and all the electrical energy(apparent power) spent, thus mathematically – a factor!. 

#2: With ONLY resistive loads the current and voltage are together – they are in phase.

#3: Inductance causes the current to fall behind – out of phase. Guess what is the electrical  angle by which the current lags the voltage called -the old roman symbol called cosPhi, 

#4: Capacitance causes the voltage to electrically lag the current. (Phase angle).



Will it add value to add the actual calculations. I am considering an online calculator but there are so many available!

Another point worth mentioning is for those considering permanent connected motor caps: A no load motor creates a much worse power factor(<0.7) then when running fully loaded(>0.8). And generally the smaller the motor the bigger the difference.

So simply motor over sizing comes with its own problems in terms of PFC and don’t not forget the caps needs to be disconnected when motor off…otherwise more money.

But seriously, what does the above mean?

If you do not have enough electrical energy to run your plant, consider installing power factor correction- you will literally have more power available for the plant itself (If you have bad power factor offcourse)!

Otherwise said: Running equipment with bad power factor is literally throwing electrical energy down the toilet – money and energy wasted!  

And more interesting read below:


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