The Dark Truth About Power Savers

Maybe many of us are familiar with the so called “power savers”. They are everywhere in the mall today and their demo is quite convincing that they have the evidence by showing us the actual measurements by using DMM(Digital Multi Meter). If you are not a technical person, you might get very convinced that you might want to buy one. Let’s find out what’s really happening and i will try not to be very technical for the benefit of the non technical persons reading this article.

The Science behind

First let me explain what is power in electricity. Power is the product of Voltage and current flowing in a device or in our case the home appliances such as TV, electric fans, etc. For appliances with motors and transformers like electric fans, washing machine and florescent bulb the power is computed as:

P = V * I * PF
Where:
P = Power in watts
V = Voltage in volts
I = Current in Amperes
PF = Power Factor

For those kind of Appliances we introduce PF for computing the power.  PF or power factor in layman’s term is the efficiency of power transfer or the ratio of the Actual power consumed by the device to the power that is supplied to the device. Power savers is actually a “power factor” correction circuit. This actually increases the power factor of the system which in turn reduces the input current(This is what they show you on their demo). You will be fooled that the input current of the appliance decrease which will lead you to the conclusion that it actually is saving electricity. But if the try to calculate, there is actually no power saving made, the current decreases but the power factor actually increased, In effect your appliance is actually consuming same power and will same electricity bill. Looking at the power equation P=V*I*PF, the simple trick is this they will show you that the input current is decrease, by increasing the Power factor. But doing the calculation, you will still have same power consumption. By the way, “power savers” is using LED lights as an power indicator, this small LED is consuming small amount of electricity so in reality you are actually adding power consumption.