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ECET 211 Electrical Machines and Controls

2016/4/27 Class Review and Wrapping Up

Comprehensive Exam, Friday, 1:00-3:00 PM, May 6, 2016

Close books/allow 1-page (8 x 11 and ½) hand-written review note, double sided

Question types o Multiple choice o Fill-in blanks o Circuit diagram/drawing completion of the unfinished part o Simple calculations

Ohm’s laws Simple circuit, resistance, current, etc Single phase Three-phase: Power, power factor, Line/phase voltage, line/phase current Transformer:

Vp/Vs, Ip/Is, Np/Ns

Three-phase Delata, Wye connections Energy, Power, Torques applications

Chapter 1. Safety in the Workplace Chapter 2. Understanding Electrical Drawings

Part 1. Symbols-Abbreviations-Ladder Diagrams o Motor Symbols o Motor Terms (abbreviations) o Motor Ladder Diagrams

Figure 2-1 Motor Control Symbols Figure 2-3 Typical ladder diagram Figure 2-4 Motor power and control circuit wiring Figure 2-5 Identification of coils and associated contacts Figure 2-6 Load and control devices Figure 2-7 Loads and places on the right and contacts on the left Figure 2-8 Stop devices connect in series and start devices connect in parallel Figure 2-8 Differentiating between multiple devices of the same type Figure 2-10 Ladder diagram with run number detailed Figure 2-11 Numerical cross-reference system Figure 2-12 Wire numbering Figure 2-13 Alternative wiring identification with documentation Figure 2-14 Representing mechanical functions (FWD, REV) Figure 2-15 Control transformers ground connection

Part 2 Wiring – Single Line – Block Diagrams o Wiring Diagrams o Single-Line Diagrams o Block Diagrams

Part 3. Motor Terminal Connections o Motor Classifications

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o DC Motor Connections Dynamic braking

o AC Motor Connections Dual voltage motor connections Multispeed motor connections Motor direction change

Part 4. Motor Nameplates and Terminology o NEC Required Nameplate Information

Motor Manufacturer, Voltage Rating, Current Rating Line Frequency, Phase Rating, Motor Speed Ambient Temperature, Temperature Rise, Insulation Class Duty Cycle, Horsepower rating Code Letter, Design Letter

o Optional Nameplate Information Service Factor, Motor Enclosure, Frame Size, Efficiency, Power Factor Thermal protection, Connection diagrams

o Guide to Motor Terminology, p. 38 Across-the-line, lock-rotor current, ..

Part 5. Manual and Magnetic Starters

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Chapter 3. Motors, Transformers and Distribution Systems Part 1. Power Distribution

o Transmission Systems o Substations

Unit Substations

High-voltage primary switchgear

Transformer sections

Low-voltage distribution section o Distribution System

Figure 3-6 Typical commercial/industrial distribution system Figure 3-7 Single-line diagram for a typical distribution system

o Power Losses o Switchboards and Panelboards

Figure 3-11 277/480V three-phase four-wire Figure 3-12 Panelboard grounding and bonding

o Motor Control Centers (MCCs) Part 2. Transformer Principles

o Transformer Operation o Transformer Voltage, Current, and Turn Ratio

Figure 3-20 Step-up transformer Figure 3-21 Step-down transformer Figure 3-22 Step-won transformer connected to a resistive load

o Transformer Power rating Single-phase kVA = I * E/1000 Three-phase kVA = (1 * E * 1.732)/1000

o Transformer Performance (losses) Core losses (Iron loss) Coil losses (copper loss) Temperature rise Voltage regulation

Part 3. Transformer Connections and Systems Transformer Polarity

High-side, Low-side Single-phase Transformers

Figure 3-27 Control Transformer used in Motor Control Applications

Figure 3-28 Typical dual voltage 480 V and 240V transformer connections

Figure 3-29 Fuse protection for both the primary and secondary of the transformer and at the ground connection for a ground control system

Three-Phase Transformers

Figure 3-30 Common transformer connections o Wye-Wye connection o Delta-Delta connection o Delta-Wye connection

Figure 3-31 Three-phase, three-wire delta transformer connection supplying power to a three-phase motor load

Figure 3-32 Wye connected, three-phase, four-wire distribution system

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Figure 3-33 Typical delta-to-wye, three-phase, four wire transformer configuration

Auto Transformer

Applications o Variable voltage o Autotransformer motor starter

Instrumentation Transformers

Current transformer (CT)

Potential transformer (PT)

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Chapter 4. Motor Control Devices o Part 1. Manually Operated Switches

o Primary and Pilot Control Devices o Toggle Switches o Push Button Switches

Figure 4-3 PB symbols and switching action Figure 4-4 Break-make PB and typical motor control circuit Figure 4-14 Emergency stop PB and motor control

o Pilot Lights Figure 4-15 Remote start/stop station with run pilot light Figure 4-17 Push-to-test pilot light

o Selector Switch Figure 4-18 Three-position selector switch

o Drum Switch Figure 4-18 Drum switch used for reversing the direction of rotation of a three-

phase motor o Part 2. Mechanically Operated Switches

o Limit Switches Figure 4-21 Limit switch symbol and configuration Micro-switch (Micro limit switch)

o Temperature Control Devices Figure 4-28 Temperature switch utilized as part of a motor control circuit (230V

fan motor) Pressure Switches

Figure 4-30 Pressure switch used as part of an air compressor control system

Float and Flow Switches

Figure 4-31 Float switch symbols and circuit (water level control)

Figure 4-32 Flow switch symbols and circuit (liquid flow control) o Part 3. Sensors

Proximity Sensors

Inductive proximity sensors

Capacitive proximity sensors Photoelectric Sensors

Through-beam scanning

Retrorefelctive scanning

Diffuse scanning

Fiber optics Hall Effect Sensors

Current measurement applications

Speed measurement Ultrasonic Sensors Temperature Sensors

Thermocouple

Resistive Temperature Detectors (RTDs)

Thermistors (Negative temperature coefficient)

IC package

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Velocity and Position Sensors

Tachometer

Magnetic pickup

Encoder Flow Measurement

Turbine flow meters

Target flow meters Magnetic Flowmeters

o Part 4. Actuators Relays

Figure 4-63 Electromechanical relay

Figure 4-64 Relay motor control circuit Solenoids

Figure 4-67 Solenoid construction and operation Solenoid Values

Figure 4-69 Solenoid valve energized and deenergized

Figure 4-70 Solenoid-operated tank filling and emptying operation Stepper Motors Servo Motors

Figure 4-74 Closed-loop servo system

Figure 4-75 DC Brushless servo motor

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Chapter 5. Electric Motors Part 1. Motor Principle

o Magnetic field and Flux o Induction (voltage/current) and Energy conversion o Applications: Motor, Generator

Part 2. Direct Current Motor o Major components of a DC motor o Major Classifications

Permanent Magnet DC Motor Series DC Motor Shunt DC Motor Compound DC Motor

o Direction of Rotation o Motor Counter Electromotive Force (EMF) and its Effects

Example 5-1 DC Motor Ia, and EMF calculation o Speed Regulation

Example 5-2 o DC Motor Speed Control Methods o DC Motor Drives

Part 3. Three-Phase AC Motors o Speed equation: N = 120*f/P o Induction motor

Squirrel-case Induction Motor, p 114 Wound-rotor Induction Motor, p. 118

o Speed-Torque Characteristics and Applications, p. 115 NEMA Design B NEMA Design C NEMA Design D

o Motor Slip Example 5-4

o Power Factor o Dual-speed three-phase squirrel-cage single winding motor

Part 4. Single-Phase AC Motors o Split-Phase Motor, p. 121 o Split-Phase Capacitor Motor (Capacitor-start), p. 123 o Dual-Speed Capacitor-Start Motors, p.124 o Reversible Permanent-Capacitor Motor, p. 124 o Capacitor-Start/Capacitor-Run Motor, p. 124 o Shaded-Pole Motor, p. 125 o Universal Motor, p. 125

Part 5. AC Motor Drives o Variable-Frequency Drive

AC to DC Converter (rectifier) DC filter Inverter (DC to AC conversion)

Volt/Hz ratio

PWM control o Inverter Duty Motor

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Part 6. Motor Selection o Mechanical Power Rating o Current o Code Letter (NEMA Locked-Rotor Code, kVA/HP) o Design Letter o Efficiency o Energy-Efficient Motors o Frame Size o Frequency o Full-load Speed o Load Requirements

Constant-torque load Variable-torque load Constant-horsepower load

o Motor Temperature Ratings Ambient temperature Temperature rise Hot-spot temperature Insulation class

o Duty Cycle Continuous duty Intermittent duty

o Torque Lock-rotor torque (LRT) = starting torque Pull-up torque (PUT) Breakdown torque (BDT) = pull-out torque Full-load torque

o Motor Enclosure Types o Metric Motors (50 Hz, 60 Hz: speeds)

Part 7. Motor Installation o Foundation o Mounting o Motor and Load Alignment

Direct-drive motors Coupling by means of Gears or Pulley/Belt Example 5-5

o Motor Bearings o Electrical Connections o Grounding o Conductor Size

Example 5-6 o Voltage Levels and Balance o Built-In Thermal Protection

Part 8. Motor Maintenance and Trouble Shooting

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o Motor Maintenance Schedule Periodic Inspections Brush and Commutator Care Testing Winding Insulation Keep Motor Clean Keep Motor Dry Check Lubrication Check for Excessive Heat, Noise, and Vibration Excessive Starting is a Prime Cause of Motor Failures

o Troubleshooting Motors DMM

Voltage measurement, continuity and motor winding resistance

Special type DMM includes: Capacitance measurement, frequency and temperature measurement functions

Clamp-on ammeter Mega-Ohmmeter Infrared (IR) thermometer Tachometer Oscilloscope

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Chapter 6. Contactors and Motor Starters

Part 1. Magnetic Contactor o Switching loads o Heater control circuits:

Delta heater load – Line current, Line voltage, three-phase power o Definite-purpose contactor

Latch coil/unlatch coil Lighting control circuit

o Contactor Assembly Shading coil

o Arc Suppression

Part 2. Contactor Ratings, Enclosures, and Solid-State Types o NEMA Ratings

NEMA contactor size guide (Figure 6-22) Example 6-1 Load Utilization Categories

Nonlinear loads

Resistive loads

Inductive loads

Capacitive loads o IEC Ratings

AC Categories DC Categories

o Contactor Enclosures Environmental factors Non-Hazardous location Hazardous Location

o Solid-State Contactor Silicon Controlled Rectifier SCR testing circuit Dual SCR for AC load Solid-state contactor digital control

Part 3. Motor Starters o Magnetic Motor Starters

Manufacturer-installed control wiring Figure 6-31 Magnetic motor starter

o Motor Overcurrent Protection Figure 6-33 Magnetic motor starter with separated mounted start-stop

pushbutton station Figure 6-34 Major functional blocks for motor operation

o Motor Overload Relays o Thermal Overload Relays o Full-load amperage (FLA) of the motor and the motor starter size o Dual-Element Fuses o NEMA and IEC Symbols

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Chapter 7. Relays

Part 1. Electromechanical Control Relays o Relay theory of operation o Relay control circuits o Relay applications

Using a relay to control a high current load with a low-current transistor circuit Diode, Transistor

o Relay styles and specifications

Part 2. Solid-State Relays o Solid-state relay operation o Specifications o Switching controls

Zero voltage crossing o Three-phase Multiple-pole SSR connections

Chapter 8. Motor Control Circuits

None

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Chapter 9. Motor Control Electronics

Diode o Basic theory o Diode Applications

Switch, flying wheel diode Rectifiers: half-wave, full-wave, three-phase full-wave

Transistor o Basic theory o Relay control, AC load on/off switching

Photo-Transistor o PLC Input Module: Full-wave rectifier, Zener diode (voltage regulator), Optical coupler o PLC Output Module: Optical coupler, Triac

IGBT o Basic theory o IGBT used in electric motor control (inverter)

Triac o Basic theory o Small AC Load control using Triac (light dimmer, small AC motor)

Chapter. 10

Adjustable Variable speed drive

Simplified circuit of a PWM inverter

Pulse-width Modulation

Inverter Motor and Drives