Chapter 1: Introduction

• Electrical materials are used in electrical construction projects for specific purposes.

• Electrical materials include electronic devices, cables, and fixtures.

• They control the flow of current and carry electrical current from the source to the load.

Chapter 2: The Free Flow

• Electrical materials can be classified based on their electrical conductivity.

• Conductors allow the flow of electric charges, such as silver and gold.

• Insulators impede the flow of electrons and tightly bind their particles.

• Semiconductors exhibit intermediate conductivity and have more charge carriers than insulators but fewer than conductors.

• Superconductors become perfect conductors at a critical temperature, with zero power loss.

Chapter 3: Resistance To Flow

• Semiconductors can be used to fabricate resistors, capacitors, inductors, and transistors.

• Integrated circuits (ICs) combine millions or billions of transistors into a small package.

• Superconductors exhibit zero power loss at a critical temperature.

Chapter 4: Passive Electrical Component

• Electrical components are classified into active components and passive components.

• Active components supply and control energy, while passive components respond to the flow of electrical energy.

• Passive components include resistors, capacitors, and inductors.

Chapter 5: Excessive Current Flowing

• Transistors are electronic devices made of semiconductor material that control the flow of voltage or current.

• Switches are electrical devices used to break the circuit and interrupt the current flow.

• Diodes allow current to flow in one direction and block current going against the flow.

• Fuses protect components from destruction due to excessive current flow.

Chapter 6: Uploading Formula V Sub Rms

• Transformer:

  • A passive electrical device consisting of cores and soft wire linked by an iron core.

  • Transfers electrical energy between two or more circuits.

• Battery:

  • An electrical device used to convert chemical energy into electrical energy.

  • Operates through electrochemical discharge reactions.

  • Tandanum battery converts chemical energy into electrical energy.

Chapter 1: Introduction to Generators

• Generators convert mechanical energy into electrical energy through electromagnetic induction

• AC generators convert mechanical energy into electrical energy in the form of alternating current

• Dynamo is an electrical generator that creates direct current using a commutator

Chapter 2: Types of Electrical Measuring Instruments

• Electrical measuring instruments are used to measure various electrical quantities

• Common types of measuring instruments include ammeters, voltmeters, ohmmeters, and wattmeters

• Ammeters measure electric current, voltmeters measure voltage, ohmmeters measure resistance, and wattmeters measure power

Chapter 3: Classifications of Electrical Measuring Instruments

• Absolute instruments give the value of the measured quantity in terms of the physical constants of the instrument

• Secondary instruments are calibrated and directly give the value of the measured quantity

• Indicating instruments have a pointer that moves over a calibrated scale to indicate the measured quantity

• Recording instruments record the measured quantity on graph paper for a desired period

• Integrating instruments measure the total quantity of electricity consumed in a circuit over a given time

Chapter 4: Effects Used in Measuring Instruments

• Magnetic effects, electrodynamic effects, and electromagnetic induction effects are used in ammeters, voltmeters, and wattmeters

• Electrostatic effects are used in voltmeters

• Chemical effects are used in DC ammeters

• Heating effects are used in ammeters and voltmeters

Chapter 5: Ammeters

• Ammeters measure electric current and can be calibrated in amperes, milliamperes, or microamperes

• Ammeters are inserted in series with the circuit being tested, increasing the resistance of the circuit by the internal resistance of the meter

• The accuracy of an ammeter is the ratio of the current with the meter to the current without the meter

• The percent loading error is the percent error in the ammeter reading due to the added resistance of the meter

Chapter 6: Shunted Ammeters

• Shunted ammeters use a shunt resistor to extend the range of the ammeter for measuring higher currents

• The current through the ammeter is equal to the current through the shunt plus the full-scale deflection current of the ammeter

• The shunt resistor value can be calculated using Ohm's law and Kirchhoff's current law

• The input resistance of the shunted ammeter is calculated using the current through the shunt and the full-scale deflection current of the ammeter

Chapter 7: Voltmeters

• Voltmeters measure potential difference or voltage in a circuit

• A simple DC voltmeter can be constructed by placing a resistor called the multiplier in series with the ammeter movement

• The sensitivity factor of a voltmeter is the reciprocal of the full-scale current

• The input resistance of a voltmeter is calculated using the full-scale voltage and the full-scale current

Chapter 8: Loading Effect in Voltmeters

• When a voltmeter is connected to a circuit, it draws current and produces a voltage drop across its coil resistance

• The loading effect is the ratio of the voltage with the voltmeter to the voltage without the voltmeter

• The unloading error is the percent error in the voltmeter reading due to the loading effect

Unloading error in percent

• Constructing a multi-range voltmeter

• Using a 50 microampere meter movement with internal resistance of 2 kilo ohms

• Ranges: 5, 10, and 25 volts

• Finding the multiplier resistance, R sub s, for each range

• Values for each range: 1.98, 1.98, and 4.98 kilo ohms

Ohmmeter

• Ohmmeter components: battery, meter movement calibrated to ohms, R sub O (current limiting resistance), R sub A (adjustable resistor for zeroing and correcting battery aging), R sub X (known resistance to be measured)

• Zeroing the ohmmeter by short-circuiting terminals A and B and adjusting R sub O for full-scale deflection

• Formula for calculating R sub X: R sub X = 1 - D/D * R sub O

• Half-scale deflection occurs when D = 1/2, R sub X = R sub O

Example: Ohmmeter measurement

• Meter movement with full-scale deflection of 50 microamperes

• Open circuit voltage at terminals A and B is 6 volts

• Ohmmeter zeroed, unknown resistor R sub X measured, produces quarter-scale deflection

• Calculating R sub O: R sub O = V/I sub M = 6 volts / 50 microamperes = 120 kilo ohms

• Calculating R sub X: R sub X = 1 - D/D * R sub O = 1 - 1/4 / 1/4 * 120 = 360 kilo ohms

Multimeter

• Multimeter measures voltage, resistance, and current

• VOM (volt-ohm milliammeter) is the most common multimeter

• VOM has a meter movement with full-scale current of 50 microamperes

• One meter movement used to measure milliamperes, DC voltage, AC voltage, and ohms

Voltmeters

• VOM voltage range extends from 2.5 volts to 5000 volts

• Sensitivity of 20 kilo ohms per volt

• Input resistance for lowest range (2.5 volts): 50 kilo ohms

• Input resistance for highest range (5000 volts): 100 mega ohms

AC Meters

• AC meters measure current and voltage that change periodically with time

• Two methods for measuring AC current or voltage: electron mechanical meter movements for low frequencies, d arson valve movement for high frequencies

Halfway Rectifier Circuit

• Simplest type of AC voltmeter

• Diode allows current flow in one direction during positive half cycle, high resistance during negative half cycle

• Resulting current through meter is RMS calibrated reading

AC Ammeters

• AC ammeters indicate average value

• Formula for converting average value to RMS: I sub B = I sub A B / 0.3185

• AC meters marked off to indicate effective or RMS value: I sub RMS = 0.707 I sub B

Halfway Rectifier Circuit with RMS Calibration

• Formula for calculating RMS voltage: V sub RMS = 0.707 I sub B (R sub S + R sub M)

• Formula for calculating input resistance: R sub I N = 0.45 V sub M / I sub M

Example: Sensitivity Calculation

• R sub S = 1 mega ohm

• Meter movement full-scale current = 50 microamperes

• Calculating RMS value of input sine wave for full-scale deflection

• Formula: V sub RMS = 2.22 I sub M R sub I N

• Calculating V sub RMS: 0.22 * 50 * 1,000,000 = 11,000,000 volts

Full Wave Rectification

• Improving sensitivity of rectifier type AC meter by using full wave rectification

• Full wave bridge detector with 100 microampere meter movement and 1 kilo ohm resistance

• Calculating size of R sub S for 50 volt RMS sine wave to produce full-scale deflection: R sub S = 450 kilo ohms

Wattmeter

• Measures DC power or real AC power

• Fixed coils indicate current, movable coil indicates voltage

• Power dissipated in DC circuit: P = V * I

• Power dissipated in AC circuit: P = V sub RMS * I sub RMS * cos Theta

Example: Wattmeter Reading

• Voltage and current supplied to a load: peak values of 162 volts and 5 amperes, phase angle of 30 degrees

• Calculating reading of the wattmeter using power formula: P = V sub RMS * I sub RMS * cos Theta

Chapter 7: Conclusion

• Vrms is equal to 0.707 V sub b or peak voltage

  • Convert into RMS for module number four

  • Vrms multiplied by Irms multiplied by cos Theta is equal to 144.534 volts times 3.535 amperes cosine 30

  • B is equal to 350.63 watts

Importance of Working Safely with Electricity

• Why is it important to work safely with or near electricity?

• What should you do if you find equipment defective?

Synchronous Classes and Midterm Exam

• Mentioned synchronous classes and midterm exam

• Told classmates about the exam

Inspecting Powered Hand Tools and Electrical Equipment

• Five points on when and how to inspect powered hand tools and other electrical equipment

• Module number four

Congratulations and Contact Information

• Congratulations on completing module number four

• Questions or concerns can be addressed through email, messenger, or Discord