Over the course of the past 12 months I have spoken to thousands of individuals regarding the energy and cost savings benefits they can receive by simply installing a power factor conditioner to their existing breaker panels. Those who took this information at face value and had this great device installed have been saving significantly on their monthly electric bills consistently since it was turned on. Those who have not I have tried to ask why they haven’t in an attempt to understand why anyone would willingly want to literally throw money out the window on a regular basis. The majority of the answers I received were shocking as they all stated that their primary reasoning was based on what their electricians had to say about them as they apparently do not think they actually work.
However, given that I am a electrical engineer who understands the how and why of these systems I have decided that perhaps it is time I publish a series based on the in depth scientific study performed by the engineering staff at the University of Santa Clara’s Department of Electrical Engineering. So that I am clear throughout this series of articles it is important that our readers understand that an Electrical Engineer is not an Electrician, nor is an Electrician an Electrical Engineer and by the end of this series you will clearly understand why. So without further ado let us get into the meat of this very eye opening study.
Types of loads and their electrical behavior
Theoretically, there are three basic types of loads in an electrical system, e.g., resistive,
inductive, and capacitive. While electrical energy is expended in pure resistive loads, electrical energy is not expended but stored in ideally inductive and capacitive loads. Although all practical loads and appliances at a consumer’s site incorporate these three types of ideal loads, it is appropriate to categorize them as mostly resistive, inductive or capacitive. The following is an example of common practical loads that are used in a household.
a. Resistive: Oven, light bulbs, iron, electric heaters, etc.
b. Inductive: Appliances with motors and transformers are examples of inductive loads
which include air-conditioners, washers, dryers, refrigerators, induction motor, power
transformer, lighting ballasts, welder or induction furnace, etc.
c. Capacitive: Rechargeable batteries, etc.
Since the currents flowing in inductive and capacitive loads are half a cycle out of phase, it is possible to make their sum zero at any particular time by adjusting their magnitudes,
consequently reducing the total current magnitude flowing through the Energy-meter (kW-hour meter) installed by the local distributors to monitor energy consumed by a subscriber. This is the essence of “power factor correction,” where power factor refers to cosine of the phase angle between the voltage and the total current. The phase angle ? = ?t, where t = time and ? = 2?/T is the angular frequency of power supply and T = 1/f, where the principle frequency f of the power being delivered is usually 60 Hz. For purely resistive load, ? = 0o, hence power factor for resistive load = cosine 0o = 1. For purely inductive and capacitive loads, power factor = cosine (±90o) = 0. Power factor correction implies to the situation where the inductive load current is balanced by capacitive load current thus reducing the total current to a minimum and the phase angle between the voltage and the total current representing the algebraic sum of the individual load currents approaches 0o, i.e., cosine 0o = 1. At lower power factor, the total current is larger and vice versa.
The current passing through the current coil of the Energy-meter installed by the power distributor to monitor power consumption is the algebraic aggregate of the individual resistive, inductive, and capacitive currents flowing in different loads of the household. Power distributors require the industrial consumers to keep the power factor of the household read at the Energy meter above say, 0.8, since power factors below 0.8 would require the distributors supply larger currents, therefore running larger generators which in turn would cost them more. Also, smaller current associated with higher power factor will minimize various resistive losses in the distribution system. Therefore, industrial consumers are charged a penalty at a predetermined rate based on their operating power factor. The ABET-2201 is capable of correcting the power factor toward various benefits of the consumer as explained in part II of this series.