May 18, 2022  
2021 - 2022 Catalog 
    
2021 - 2022 Catalog
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HVAC 225 - Commercial Refrigeration II

Credits: 3
Instructional Contact Hours: 3

Develops additional skills and understanding in the servicing of commercial units such as walk-in coolers, reach-ins, display cases, and commercial icemakers. Focuses on electrical systems and diagrams. Analyzes single-phase systems and three-phase systems. Credit may be earned in one of the following: HVAC 225, RHA 225 or SKPT 225 .

Prerequisite(s): HVAC 123  
Corequisite(s): None
Lecture Hours: 35 Lab Hours: 10
Meets MTA Requirement: None
Pass/NoCredit: Yes

Outcomes and Objectives
  1. Demonstrate knowledge of electrical symbols and basic electrical diagrams.
    1. Identify electrical symbols used in commercial refrigeration.
    2. Trace circuits in basic refrigeration and air conditioning diagrams.
    3. Identify voltages, current, and resistance in basic refrigeration circuits.
    4. Use an Ohmmeter to measure resistance at switches and component loads.
    5. Use a voltmeter to measure voltages at switches and component loads.
    6. Identify basic switches in open and closed positions.
  2. Demonstrate knowledge of types of single-phase compressor motor circuits.
    1. Identify motor winding characteristics, types, and winding speeds.
    2. Measure motor winding resistances using engineering standard methods and the Ohmmeter.
    3. Trace motor winding circuits in a split phase compressor motor.
    4. Trace motor winding circuits in a PSC (Permanent Split Capacitor) compressor motor.
    5. Trace motor winding circuits in a capacitor start motor.
    6. Trace motor winding circuits in a capacitor, start capacitor, run circuit.
    7. Trace motor winding circuits in a multi-speed motor.
    8. Trace motor winding circuits in a reversible motor.
    9. Identify sine wave characteristics of 110 VAC compressor motors for current and voltage.
    10. Identify sine wave characteristics of 240 VAC compressor motors for current and voltage.
    11. Trace motor winding circuits for a 240 VAC motor.
    12. Identify RLA and LRA motor requirements.
    13. Identify motor temperature ranges, working conditions, and insulation types.
  3. Demonstrate knowledge of types of three-phase compressor motor circuits.
    1. Trace the motor winding circuits of a three-phase Delta wound compressor motor.
    2. Trace the motor winding circuits of a three-phase Wye wound compressor motor.
    3. Identify methods of reversing motor direction on a three-phase motor.
    4. Identify sine wave characteristics for current and voltage in three-phase circuits.
    5. Identify how three-phase compressor motors are made into variable speed motors.
    6. Identify compressor safety and protection circuits.
    7. Identify compressor control circuits for three-phase compressors.
  4. Demonstrate knowledge of sine wave characteristics.
    1. Identify conditions of amplitude, time, wavelength, and peak values.
    2. Identify frequency, phase, positive, and negative in response to the sine wave.
    3. Identify average values, true values, and peak value.
    4. Identify sine wave forms for AC electricity and DC electricity.
    5. Identify the characteristics of voltage and current in relation to the sine wave.
    6. Identify how current sine wave and voltage sine wave respond to maximum power factor.
    7. Identify how the current sine wave and the voltage sine wave respond in single-phase 110 VAC current applications.
    8. Identify how the current sine wave and voltage sine wave respond in single-phase 240 VAC current applications
    9. Identify how the current sine wave and the voltage sine wave respond in three-phase applications.
    10. Identify how the current since wave and the voltage sine wave respond to capacitive reactance.
    11. Identify how the current sine wave and the voltage sine wave respond to inductive reactance.
  5. Demonstrate knowledge of capacitors, relays, and starters.
    1. Identify the parts of capacitor and its operation
    2. Identify types of capacitors
    3. Identify voltage characteristics and micro farad capacities of a capacitor.
    4. Identify methods of testing a capacitor.
    5. Identify how a current relay works.
    6. Identify how a voltage relay works.
    7. Additional supplies cost of $20 per student Identify how a thermal relay works.
    8. Identify how a single-phase motor starter works.
    9. Identify how a single-phase motor starter works
    10. Identify how a three-phase starter works.
    11. Identify how a contactor works.
    12. Use an ohmmeter to test these starters and relays.
      1. Current relay
      2. Voltage relay
      3. Thermal relay
      4. Hot wire relay
      5. Single-phase starter
      6. Three-phase starter
      7. Contactor



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