Basic electrical math

Basic Electrical Math,[object Object],Presented by Jim Wylie,[object Object]

This pre-class is to help you to prepare for the Solar Technician Course. The goal is to be able to understand the technical lessons of the main course, not become frustrated or fall behind the other students. ,[object Object],Jim Wylie, your instructor, has posted regular office hours to help you to successfully complete the Solar Technician Course. If you need times not posted, contact Jim by email or Blackboard and make other arrangements.,[object Object]

Introduction,[object Object],[object Object]

PV Installers must be able to do simple geometric and trigonometric problems

The instructor assumes that students are capable of simple addition, subtraction, multiplication and divisions.

The instructor realizes that students may not remember or have a good foundation in algebra. ,[object Object]

Ohms Law is possibly the most important concept to learn in electrical technology. It is used by every electrician and equally used by solar installers. The formula E=IR explains the relationship of current, resistance to the voltage of all electric circuits. In this lesson we will use the Ohms formula to explain the relationship of volts, amps and ohms.,[object Object],Learn this lesson well before you continue to Lesson Two. If you feel that you are not learning the lesson, contact the instructor during his office hours for some help.,[object Object],Ohms Law V=IR,[object Object]

Lesson 1: Apply Ohms Law,[object Object],The formula V=IR is manipulated to calculate the I (current) when we know the V (voltage) and R (resistance),[object Object],You must learn that V=IR and that,[object Object],V=Voltage, I=Amps and R=Resistance,[object Object],Repeat: Learn this formula – Electrical potential equals the current times the resistance or V=IR. The electrical potential is measured in volts. Current is measured in amps and resistance is measured in ohms.,[object Object]

Calculate the Current,[object Object],If V=IR, to get I= ? First divide on both sides of the equal sign by R.,[object Object],V/R=IR/R the answer is V/R=I or reverse the formula I=V/R,[object Object],Explanation:,[object Object],The current in amps is equal to electrical potential in volts divided by resistance in ohms or the current in amps is inversely proportional to the resistance in ohms and directly proportional to the electrical pressure (potential) in volts. ,[object Object]

Lesson 1: Continue,[object Object],Using the same process for calculating (I), calculate (R),[object Object],Remember that Ohms Law is V=IR (memorized by now),[object Object],We calculate the formula for resistance (R) when you know what the voltage potential and current in amps are ?,[object Object],Go to the next slide and see if you have the correct answer reasoning. If the answer is wrong go back to the first slide in this lesson before continuing. ,[object Object]

Answer: Find R, If V=IR,[object Object],V=IR by dividing both sides of the equal sign by I. V/I=IR/I The results is V/I=R or R=V/I,[object Object],QUIZ: Describe the process and results in math terms? Stand on your head for the answer,[object Object],You can say that the resistance in ohms is equal to electrical potential in volts divided by current in amps or you can say that resistance in ohms is inversely proportional to the current in amps and directly proportional to the electrical pressure (potential) in volts. ,[object Object]

Calculate the Resistance,[object Object],If V=IR, to get R= ? First divide on both sides of the equal sign by I.,[object Object],V/I=IR/I the answer is V/I=R or reverse the formula R=V/I,[object Object],Explanation:,[object Object],The Resistance in ohms is equal to electrical potential in volts divided by current in amps or the resistance in ohms is inversely proportional to the current in amps and directly proportional to the electrical pressure (potential) in volts. ,[object Object]

[object Object],If you do not understand the lesson slide then reread it until it makes sense or try memorizing it and continue on to the next slide.,[object Object],Repeat this same procedure for each slide until you finish the lesson. ,[object Object], The review slide will contain all variations of Ohms Law – memorize the variations if you cannot calculate them.,[object Object],The last slide in the lesson will be using real numbers instead of letters. This might make more sense to you. ,[object Object],Lastly, review the complete lesson and if all else fails call the instructor for help.,[object Object]

Lesson 1 Review,[object Object],[object Object]

Explain each of the Ohm’s Law variation with mathematical terms –

Using numbers is usually easier than letter in a formula. Go to the self-test next slide and see if you know how to use Ohm’s Law. ,[object Object]

Answer to Problems,[object Object],V=IR,[object Object],R=V/I,[object Object],I=V/R,[object Object]

Lesson 2: Series Electric Circuits,[object Object],A series circuit is connected in a line with the back side of electrical object attached to the front side of the next electrical object.,[object Object]

Lesson 2: How It Works,[object Object],SERIES CIRCUITS,[object Object],A Series Circuit has only one path to ground, so electrons must go through each component to get back to ground. All loads are placed in series.,[object Object],1. An open in the circuit will disable the entire circuit. ,[object Object],2. The voltage divides (shared) between the loads.,[object Object],3. The current flow is the same throughout the circuit.,[object Object],4. The resistance of each load can be different,[object Object]

Lesson 2: Voltage Drop,[object Object],VOLTAGE DROP CALCULATIONWhen current flows in a circuit, the presence of a resistance in that circuit will cause the voltage to fall or drop as it passes through the resistance. The resultant difference in the voltage on each side of the resistance is called a voltage drop. When current (I) flows in the following circuit, voltage drops V1 and V2 across resistances R1 and R2 can be determined as follows from Ohm's law. (The value of current I is the same for both R1 and R2 since they are connected in series.),[object Object]

Series Voltage Drop Calculation,[object Object]

Series Circuit Summary,[object Object],Remember these points and understand how the voltage drop calculations are done,[object Object],There is only one path to the ground,[object Object],Current remains the same throughout the circuit,[object Object],The presence of a resistance in the circuit will cause the voltage to drop,[object Object]

Lesson 3: Parallel Circuits,[object Object],A parallel circuit is like a ladder with the steps being the resistance between the sides representing the positive and negative wires. Voltage and current flows independently through each resistant step.,[object Object]

Lesson 3: How It Works,[object Object],PARALLEL CIRCUITA parallel circuit has more than one path for current flow. The same voltage is applied across each branch. If the load resistance in each branch is the same, the current in each branch will be the same. If the load resistance in each branch is different, the current in each branch will be different. If one branch is broken, current will continue flowing to the other branches. ,[object Object]

Lesson 3: calculations,[object Object],Resistance in a parallel circuit is calculated with the formula: ,[object Object],Current is calculated by the formula:,[object Object]

Parallel Circuit Summary,[object Object],Remember these points and understand how the resistance and current calculations are done,[object Object],A parallel circuit will have more than one path to the ground,[object Object],The same voltage will appear across each branch,[object Object],Different current will result from different resistance of the branches,[object Object],If a branch is opened current will continue through the other branches,[object Object]

Lesson 3: Power Sources,[object Object],We will use our knowledge of Ohms Law, Series and Parallel electric circuits to understand how power sources like batteries and solar panels work.,[object Object]

Basic electrical math

Basic electrical math

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