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Commercial Refrigeration II

HVAC 225

Commercial Refrigeration II

HVAC 225

Course Description

Prerequisite: HVAC 123 or RHA 123. 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. (35-10)

Outcomes and Objectives

Demonstrate knowledge of electrical symbols and basic electrical diagrams.

Objectives:

  • Identify electrical symbols used in commercial refrigeration.
  • Trace circuits in basic refrigeration and air conditioning diagrams.
  • Identify voltages, current, and resistance in basic refrigeration circuits.
  • Use an Ohmmeter to measure resistance at switches and component loads.
  • Use a voltmeter to measure voltages at switches and component loads.
  • Identify basic switches in open and closed positions.

Demonstrate knowledge of types of single-phase compressor motor circuits.

Objectives:

  • Identify motor winding characteristics, types, and winding speeds.
  • Measure motor winding resistances using engineering standard methods and the Ohmmeter.
  • Trace motor winding circuits in a split phase compressor motor.
  • Trace motor winding circuits in a PSC (Permanent Split Capacitor) compressor motor.
  • Trace motor winding circuits in a capacitor start motor.
  • Trace motor winding circuits in a capacitor, start capacitor, run circuit.
  • Trace motor winding circuits in a multi-speed motor.
  • Trace motor winding circuits in a reversible motor.
  • Identify sine wave characteristics of 110 VAC compressor motors for current and voltage.
  • Identify sine wave characteristics of 240 VAC compressor motors for current and voltage.
  • Trace motor winding circuits for a 240 VAC motor.
  • Identify RLA and LRA motor requirements.
  • Identify motor temperature ranges, working conditions, and insulation types.

Demonstrate knowledge of types of three-phase compressor motor circuits.

Objectives:

  • Trace the motor winding circuits of a three-phase Delta wound compressor motor.
  • Trace the motor winding circuits of a three-phase Wye wound compressor motor.
  • Identify methods of reversing motor direction on a three-phase motor.
  • Identify sine wave characteristics for current and voltage in three-phase circuits.
  • Identify how three-phase compressor motors are made into variable speed motors.
  • Identify compressor safety and protection circuits.
  • Identify compressor control circuits for three-phase compressors.

Demonstrate knowledge of sine wave characteristics.

Objectives:

  • Identify conditions of amplitude, time, wavelength, and peak values.
  • Identify frequency, phase, positive, and negative in response to the sine wave.
  • Identify average values, true values, and peak value.
  • Identify sine wave forms for AC electricity and DC electricity.
  • Identify the characteristics of voltage and current in relation to the sine wave.
  • Identify how current sine wave and voltage sine wave respond to maximum power factor.
  • Identify how the current sine wave and the voltage sine wave respond in single-phase 110 VAC current applications.
  • Identify how the current sine wave and voltage sine wave respond in single-phase 240 VAC current applications
  • Identify how the current sine wave and the voltage sine wave respond in three-phase applications.
  • Identify how the current since wave and the vo0ltage sine wave respond to capacitive reactance.
  • Identify how the current sine wave and the voltage sine wave respond to inductive reactance.

Demonstrate knowledge of capacitors, relays, and starters.

Objectives:

  • Identify the parts of capacitor and its operation
  • Identify types of capacitors
  • Identify voltage characteristics and micro farad capacities of a capacitor.
  • Identify methods of testing a capacitor.
  • Identify how a current relay works.
  • Identify how a voltage relay works.
  • Additional supplies cost of $20 per student Identify how a thermal relay works.
  • Identify how a single-phase motor starter works.
  • Identify how a single-phase motor starter works
  • Identify how a three-phase starter works.
  • Identify how a contactor works.
  • Use an ohmmeter to test these starters and relays.

Demonstrate knowledge of electrical controls.

Objectives:

  • Identify the characteristics and operation of these controls.
  • Use an Ohmmeter to test electrical controls
  • Use a voltmeter to test electrical controls. Use an amp meter to test electrical controls.

Demonstrate knowledge of commercial single-phase wire diagrams and three-phase diagrams.

Objectives:

  • Trace commercial diagram circuits for single-phase AC volts.
  • Trace commercial diagram circuits for three-phase AC volts.
  • Trace refrigeration control circuits.
  • Identify overload and control circuits for three-phase compressors.
  • Use a voltmeter to test operation of control circuit and three-phase circuits.