Are low voltage saving devices effective? Is There Such Thing as Power Saver?
Household power saving devices recently caught the attention of consumers. These are small devices which are plugged in any of the AC sockets (mostly near the energy meter). It has a lot of names such as power saver, electrical energy saver, power factor regulator, power capacitor, capacitor bank, just to name a few.
Some of the manufacturers claim that their power savers can save up to 40% of energy. But does it really help in reducing our electricity bill?
From my background and knowledge as an Electrical Engineering student, this electric device(let’s call it capacitor bank) works based on the concept of power factor correction.
Power consists of two (2) components, the real power and the reactive power. Real power or average power is the actual power developed and only exists at resistors. Meanwhile, reactive power is the power developed due to reactance, be it inductive or capacitive. Power factor is the ratio of real power to apparent power. Power factor also can be denoted as cos θ.
Before we proceed , I’d like to tell you that the power meters in our homes only measure real power. It does not measure reactive power. So our monthly electricity bill is plainly based on how many units of real power we used at home. Now, power factor correction is the process of altering the power factor so that it is closer to unity (cos θ = 1). If a capacitor bank is connected in parallel with the load (plugged into a socket outlet), it can subsequently improve the power factor to a value close to unity as shown in the figure below. But look carefully, after the power factor correction, only reactive power is reduced while there is no change to the real power. So, I have to say that the use of capacitor bank (power savers) would not reduce energy consumption nor reduces your monthly electricity bill.
Power factor correction only reduces reactive power (var), not real power (W)
However, there are still some advantages of power factor correction. By connecting the power saving device to your AC socket, the electrical load on the utility company ( best example would be MERALCO for areas like Bulacan, NCR, Rizal, Cavite and Laguna) is reduced. This allows the utility company to supply the surplus power to other consumers without increasing its generating capacity.
Thus, although the use of electrical energy saver does not help in lowering the cost of your monthly bills, it actually improves the efficiency in the power usage and in a way more environmental friendly.