Electrical Calculations HandBook by John M. Paschal, Jr.
بسم الله الرحمن الرحيم
كتاب:
Electrical Calculations HandBook By John M. Paschal, Jr
Contents
Chapter 1. Basic Electrical Working Definitions and Concepts 1
Voltage as Potential Difference 1
Current 3
Resistance 4
Direct-Current (dc) Voltage Sources 4
Direct and Alternating Current 5
dc Voltage 6
Current Flow in a Resistive Circuit 15
Current Flow in a Series Resistive Circuit 16
Voltage Division in a Series Circuit 18
Power Rating of a Resistor 18
ac Voltage 23
ac Circuits with Resistance 23
ac Phase Angle and Power 26
Current and Power in a Single-Phase ac Circuit 33
Current and Power in a Three-Phase ac Circuit 33
Inductive Reactance 42
Capacitive Reactance 46
Impedance 52
Chapter 2. Three-Phase Systems 55
Wye-Connected Systems 58
Delta-Connected Systems 60
Chapter 3. Mathematics for Electrical Calculations
Power Factor Correction, and Harmonics 69
Changing Vectors from Rectangular to Polar Form and
Back Again 69
Adding Vectors 70
Multiplying or Dividing Vectors 74
Solving for Current and Power Factor in an ac Circuit
Containing Only Inductive Reactance 75
Solving for Current and Power Factor in an ac Circuit
Containing Both Inductive Reactance and Resistance in
Series with One Another 77
Solving for Current and Power Factor in an ac Circuit
Containing Two Parallel Branches That Both Have Inductive
Reactance and Resistance in Series with One Another 77
Solving for Current and Power Factor in an ac Circuit
Containing Parallel Branches, One of Which Has Inductive
Reactance and Resistance in Series with One Another and
the Other of Which Has a Capacitive Reactance 79
Electrical Power in Common ac Circuits 79
Power Factor Correction to Normal Limits 87
Real Power (Kilowatts), Apparent Power (Kilovoltamperes),
Demand, and the Electrical Utility Bill 90
Power Factor Correction System Design in an Electrical Power
System Containing No Harmonics 93
Power Factor Correction System Design in an Electrical Power
System Containing Harmonics 104
Calculating the Parallel Harmonic Resonance of an Electrical
Power System Containing Capacitors 107
Resulting Values of Adding Harmonic Currents or Voltages 108
Acceptable Levels of Harmonic Current and Voltage 110
The Harmonic Current-Flow Model 111
Effects of Harmonic Current on Transformers 114
Effects of Harmonic Voltage on Motors 116
Harmonic Current Flow through Transformers 116
Harmonic Filters 117
Harmonics Symptoms, Causes, and Remedies 122
Chapter 4. Conductors 125
Conductors, Conductor Resistance, Conductor and Cable
Impedance, and Voltage Drop 125
Calculating the One-Way Resistance of a Wire 125
Calculating the Impedance of a Cable 133
Calculating Voltage Drop in a Cable 140
Calculating dc Resistance in a Bus Bar 143
Calculating Heat Loss in a Conductor 143
Wires and Cables 143
Determining Wire Size Given Insulation Type, Circuit Breaker
Clearing Time, and Short Circuit Current 160
Selecting the Proper Insulation for an Environment 161
Aluminum Conductors 170
Conductor and Cable Selection 170
Chapter 5. Short-Circuit Calculations 179
Sources of Short-Circuit Current 182
The Ability of the Electrical Utility System to Produce
Short-Circuit Current 183
Short-Circuit Contributions of On-Site Generators 184
Short-Circuit Contributions of Motors 185
Let-Through Values of Transformers 187
Let-Through Values of Reactors 188
Let-Through Power Values of Cables 189
Sample Short-Circuit Calculation 190
Chapter 6. Generator Sizing Calculations 195
Sizing a Gas-Turbine Generator Set for a Known Kilowatt Load 196
Sizing a Reciprocating Engine-Driven Generator Set for a
Known Kilowatt Load 198
Sizing of Generator Feeder Conductors 200
Chapter 7. Grounding 205
The Functions of Grounding 205
Calculating the Resistance to Remote Earth of Ground Rods 208
Grounding-Electrode Conductors 211
Equipment-Grounding Conductors 211
Methods of Grounding Systems 215
Obtaining the System Grounding Point 217
Chapter 8. Lighting 221
The Lumen Method 221
The Point-by-Point Method 223
Indoor Lighting 229
Lighting Rules of Thumb 245
Chapter 9. Transformers 251
Three-Phase Transformers 255
Overcurrent Protection of Transformers 265
Buck-Boost Autotransformers 275
Chapter 10. Motors 285
Selecting Motor Characteristics 286
Calculating Motor Running Current 295
Calculating Motor Branch-Circuit Overcurrent Protection
and Wire Size 296
Chapter 11. Raceways 311
Raceway Types and Their Characteristics 311
Chapter 12. Overcurrent Devices 319
Overcurrent Devices: Fuses and Circuit Breakers 319
Fuses 321
Circuit Breakers 323
Medium-Voltage and Special-Purpose Circuit Breakers
and Relay Controllers 325
Chapter 13. Circuits for Special Loads 335
Designing Circuits for Various Electrical Loads 335
Designing an Electrical System for a Commercial Building 339
Designing an Electrical System for an Industrial Facility 349
Chapter 14. Electrical Design and Layout Calculations 357
Straight-Through Pull Box in a Conduit System 357
Angle Pull Box in a Conduit System 358
Working Space Surrounding Electrical Equipment 358
Minimum Centerline-to-Centerline Dimensions of Knockouts
to Provide for Locknut Clearance 364
Chapter 15. Electrical Cost Estimating 371
Electrical Takeoff and Personnel-Hour Cost Estimating 371
Factoring of Labor Units 397
Estimate of Project Expense 409
Engineering Economics Calculations Considering the Time
Value of Money 411
Chapter 16. Conversion Calculations 425
Temperature Conversion Calculations 425
Frequently Used Conversion Calculations 425
Multiple Conversion Calculations 425
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