Title: Lab Assignment
Course: HET 119 HVACR Electricity II > Section: HET 119 HVACR Electricity II

Lab Assignment

page 1
Week 9 Lab Assignment: Control Devices

Recommended Materials
1. Lab Sheet
2. Pencil and paper
3. HVAC Textbook
4. Internet Search
5. Test Board 24”x 24”
6. Wires
7. Refrigeration Thermostat
8. Low Pressure Controls
9. Liquid Line Solenoid
10. 3 Light bulbs
11. Jumper wires

Scope

This lab will help the student to understand Control Devices and how it is used in electrical circuits. The student will wire controls to loads in combination circuits.

Procedures

1. Follow the diagram posted, use light bulb as the loads.
2. On a test board, wire a circuit as a refrigeration system with a pump-down circuit.
3. Have the instructor specify the controls you will need for this assignment.
4. Have the instructor to inspect the circuit.
5. Cycle the thermostat and witness the action of the loads.
6. Use a jumper wire to bypass the pressure control.
7. Witness the action from the thermostat.
8. Explain what is the purpose of these controls:
  1. Liquid line solenoid
  2. Contactor
  3. Relay
  4. Transformer
  5. Limit Switch
  6. Thermostat
  7. Remote sensing bulb thermostat
  8. Low Pressure Control
  9. High Pressure Control
  10. Oil Pressure Safety Control
  11. Thermo-Overload

Research Questions

1. Explain the sequence of a refrigeration pump-down system operation.
2. What is the operation and purpose of a refrigerant defrost termination switch.
3. What is the purpose of the low pressure switch?
4. What is the purpose of the liquid line solenoid?

Click on the file below to download the Lab Assignment
- HET 119 Wk 9 Lab.docx (76.8 KB)