Power Save 1200 University Study

OPERATION OF THE POWER-SAVE 1200 POWER CONDITIONING UNIT

Ayhan A. Mutlu, Ph.D., and Mahmud Rahman, Ph.D.

Department of Electrical Engineering, Santa Clara University

500 El Camino Real, Santa Clara, CA 95053

 

December 12, 2004

 

1. Introduction

With the advent of electricity and technological breakthroughs, electrical energy has been made available at a reasonable cost through an elaborate and efficient distribution grid system to households and businesses alike operating various kinds of appliances that run on electricity. The local distributors of electrical energy charges the consumers based on the consumers’ rate of electrical energy consumption called “power” expressed in numbers of thousands of watts, i.e., kilowatts (kW). The electrical quantity kW that represents the rate of energy consumed can be minimized if the circuitry is optimized in a way that there is less “spurious” energy lost. The Power product, if incorporated into the electrical circuit, is able to achieve such minimization. In addition, the Power-Save 1200 brings about a number of other benefits to the consumer without introducing any adverse effects, or "side effects." A good understanding of various aspects of how electrical power is consumed in a circuit is therefore essential to understand how this product works. The principle of operation of the Power-Save 1200, based on theoretical concepts which are substantiated by measurement evidences, is presented in the following.

 

2. 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 è = ùt, where t = time and ù = 2 ð/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, è  = 0^o , hence power factor for resistive load = cosine 0^o = 1. For purely inductive and capacitive loads, power factor = cosine (±90^o) = 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 0^o, i.e., cosine 0^o

= 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 Power-Save 1200 is capable of correcting the power factor toward various benefits of the consumer as explained below.

 

 

 

 

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Types of Loads

There are three basic types of loads in an electrical system, e.g., resistive, inductive, and capacitive.

Role of the Capacitor

A device that stores energy in the electric field established between a pair of conductors.

Power-Save 1200 

Is capable of correcting the power factor toward various benefits of the consumer.