Electric Fans Electricity Consumption At Different Speeds

Electric Fans Electricity Consumption At Different Speeds

It’s a very common question for those who know at least a bit of electricity; is an electric ceiling fan consumes less electricity when it runs at low speed? Are there any changes that happen at a different speed?

For making clear, a ceiling fan may be the most used electric home appliance. A regulator controls its uses and. Is it possible that when we speed down the fan’s speed using a regulator, use low electricity, or speed up the fan to consume more electricity? Let’s read a brief discussion about this topic.

Does Fans’ Electricity Compulsion Depend on Speed?

The answer to the question is, YES! It actually depends. Let’s make it clear. We normally use three types of regulators for controlling the fan’s speed.

  • Resistor Based Regulator
  • Capacitor Based Regulator
  • Electronic Regulator

Resistor Based Regulator

The resistor-based regulator is a big-size regulator that we were using earlier in the ’90s.
The reason for calling it a resistive regulator is that it is fitted with some weird resistors. The resistors in the box are arranged so that when we turn the knob of the regulator, we actually change the line’s resistance.

When the resistor is connected in series with the fan, it drops the voltage. As a result, the more voltage is dropped, the less voltage the fan gets. Therefore, at low voltages, less current flows through the fan, and the fan’s speed decreases. That means the resistor regulator basically reduces the amplitude of voltage/current.

Follow the example:

The voltage drop of the resistor is V
Current is I
and the resistance is R

So, V = IR

That means,

More resistance = More voltage drop
Low resistance = Low voltage drop

However, in this case, it should be noted that the resistor basically completes the loop by causing electrons to collide with its internal particles. The higher the barrier resistor, the greater the amount of collision. It reduces the electric current of the fan and generates a lot of heat due to the collision.

And this generated heat, H = I ^ 2R.

That is system loss. As a result, when the resistor is connected to the fan, it reduces the fan’s speed by reducing the flow at which the system loses due to heat.

The fan regulator formula is,
Fan + Regulator = Fixed Power

So even if the speed can be controlled with a resistor-based regulator, the compulsion of electricity cannot be controlled.
Resistor Based Regulator

Note: The knob is not attached to any resistor during full speed.

Capacitor Based Regulator

So now, the primary question is how the capacitor-based regulator reduces the fan’s speed? Does it have the same power loss as the resistor-based regulator?

The working principle of a capacitive regulator is very simple. These regulators are also connected to the capacitor and the fan as a series connection, just like the resistive regulators.
Without going into the complex equation of capacitive reactance and total impedance, let us consider the voltage drop of the capacitor in a series connection to get this easily.

Since it is connected in series, the capacitor drops the voltage just like the resistor.


The relationship between the voltage drop is V
The stored charge is Q
And the capacitance is C

So, V = Q / C

That means,

High capacitance = Low voltage drop
Low capacitance = High voltage drop

The lower the voltage drop of the capacitor, the more voltage the fan will run itself, increasing the current speed. Again, the higher the voltage drop across the capacitor, the less voltage the fan will get to run itself, which will reduce the current and speed.

This means that the capacitive regulator reduces the amplitude of voltage/current, just like the resistive regulator. However, since capacitors do not drop the voltage by colliding with electrons like resistors, there is no system loss due to I^2R like resistors.

Capasitor Based Regulator

This is basically the difference between a capacitor and a resistor.

So I think you now understand that reducing the fan’s speed for using a capacitor-based regulator reduces electricity costs.

Electronic Regulator

Now let’s come to the topic of electronic fan regulators. This non-linear electronic fan regulator is not as simple as the above two linear regulators. Instead, it contains semiconductor devices (TRAC, DIAC), capacitors, resistors, and potentiometers.

The resistive or capacitive regulator reduces the speed by controlling the amplitude of the voltage/current, but the electronic aggregator is of the AC phase. Controls conduction timing. This is called phase angle control. This regulator does not pass the whole part of the AC sine wave through the fan, but some part of the sine wave flows through the fan, and the rest does not flow. That means electronic regulators also reduce current consumption while the fan runs at low speed.

We normally don’t use an Electronic regulator at our home.

After all that discussion, we can conclude that, while using an electronic or capacitor-based regulator, current consumption can be less based on the fan’s speed. Hence, lesser is the speed; lesser is the power – consumption.


About the Author: BDElectricity Staff

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