Chapter 1: Basic Electrical Theory and Electrical Quantities

Chapter Overview

Chapter 1 will cover basic electrical theory and electrical quantities. Understanding basic electrical theory as an electrician working around such a hazardous energy form is important. Understanding electrical theory will help in installing electrical systems not only properly but also safely.

Electrical Theory Review

Conductors are materials that are good at “conducting” electrical flow measured in amps (A), known commonly as electricity. The conductor’s ability to allow the flow of electrons is directly related to the amount of valence electrons present in the outer or “valence” shell of an electron’s atom. For example, silver is an excellent conductor since it only has one valence shell electron. This lone electron is more easily displaced from its orbit around the nucleus, hence its ability to facilitate the flow of current. Copper is another commonly used conductor as it contains two valence electrons, and it adequately facilitates current flow while also being cheaper and more abundant than better but less common and more expensive conductors like silver or gold.

Insulators are materials that contain a full 8 valence electrons in their outer shell which are not easily displaced from their orbit around the electron nucleus. This is the reason insulators resist the flow of electrical current. Glass, rubber and porcelain are all examples of materials that resist the flow of electrical current. This resistance (R), measured in ohms, to current flow is especially advantageous when applied to wires used for electrical circuitry where the inner conductor is insulated to protect people and property for the hazards that arise from the use of electricity.

Semi-conductors are just what they sound like, semi good at conducting electricity. The basic materials used for most semiconductor are germanium and silicon, which in their pure state do not have enough free electrons to support a useful amount of current flow. Therefore, their structure must be altered to make the crystal either more or less conductive. All semi-conductors contain four valence electrons, which makes them excellent candidates for the basic building blocks for all solid-state (digital) devices including photovoltaic (PV) cells. They are commonly “doped” with arsenic, boron, or gallium to alter their basic electrical properties to be either better or worse at conducting electrical current.

Doping, as it refers to semiconductor materials, is the act of changing the crystalline structure of a semiconductor material by adding impurities to alter its conductive properties. The final operating characteristics of the semi-conductors can be controlled through the number of impurities added to the basic crystalline structure of the individual semi-conductors. Due to the compact size, they inherently do not tolerate high levels of current flow as there are no moving parts to speak of.

Electrical Circuits and Components

In any electrical circuit, not all the energy that is produced is utilized due to inefficiencies in the electrical system. This inefficiency is known as the power factor. Power factor is the ratio of true power and apparent power. It is the ratio of how much energy, or “true power” measured in watts (W), is actually used by the system. Apparent power, measured in volt-amps (VA), is the total amount of energy available. The power factor is determined by dividing the apparent power (VA) or total power supplied by the true power (W) that is actually consumed. Think of the power factor like a bag of chips. You pay for the full bag, but the bag is never full. In essence you are paying for the whole bag, but you only get to eat portion of what the bag promised.

Capacitors are electrical devices that store and discharge electrical current. They are comprised of two conductors separated from each other by a dielectric. Capacitors are commonly used to correct power factor and efficiency issues in large electrical systems that contain high inductance e.g. manufacturing plant with a large number of inductive loads like motors. The capacitors are used to effectively cancel out the high inductance caused by large motor loads. This in turn brings the system back into balance and ultimately leads to higher efficiency. This higher efficiency is advantageous to the power utility as they do not have to supply a large amount of power that the consumer is not utilizing by still must pay for, just like paying for the entire bag of chips but only getting to eat a fraction of what the bag could potentially hold.

Editing note: Insert video for power factor here: CNM glass video?