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  • Air Conditioning and Refrigeration

Control Systems

Control Systems

Introduces the need for control, control methods, and system basics. Includes information on self-powered, pneumatic, hydraulic, electric, and electronic systems. Covers various sensors and controlled devices. Covers the basics of two-position, floating, and proportional control systems and their maintenance and troubleshooting. Discusses the various processes requiring control in a refrigeration or air-conditioning system. This course has no prerequisites. Control Systems is available in online technical training and course manual formats.

TPC Training Systems is authorized by IACET to offer 0.5 CEUs for this program.

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TPC Training is authorized by IACET to offer 0.5 CEUs for Control Systems online training.

Lesson 1 - Introduction to Control Systems


Automatic control; Control system basics; Two-position, floating, and proportional control; Open- and closed-loop control; Operating power

Learning Objectives:
– Explain why control systems are needed and name devices used to control environmental conditions.
– Define the terms used to describe control systems-controlled variable, controller, controlled device, setpoint, control point, and controlled medium-and
   name the basic elements of a control system.
– Describe the action of two-position, floating, and proportional control.
– Explain how anticipators work.
– Compare open-loop and closed-loop control.
– Compare the basic requirements of pneumatic/hydraulic control systems to those of electric/electronic control systems.

Lesson 2 - Sensors and Controlled Devices


Temperature, humidity, and pressure sensors; Dampers; Valves; Variable-speed drives

Learning Objectives:
– Explain the need for a sensor in a control system.
– Name and explain the operation of three kinds of temperature sensors.
– Define relative humidity, state the range required for human comfort, and describe common humidity sensors.
– Name three common pressure sensors and explain their operation.
– Explain the operation of two-position dampers and valves in shutoff and throttling applications.
– List the advantages of variable-speed drives over older methods of speed control.

Lesson 3 - Automatic Control Systems


Two-position, floating, and proportional electric control; Pneumatic systems, controllers, actuators, relays, and switches; Electronic systems; Proportional band, gain, and PID control

Learning Objectives:
– Describe the operation of two-position, floating, and proportional electric controllers.
– List the equipment needed for a pneumatic control system.
– Name several pneumatic relays and switches, and explain why each is used.
– Discuss the advantages and basic operation of electronic controls.
– Define resolution, sensitivity, proportional band, and gain, and explain how they are related.
– Distinguish between integral and derivative action, and explain how each can improve system performance.

Lesson 4 - Control of Refrigeration and Air-Conditioning Processes


Primary control; Low-pressure, high-pressure, and high-temperature controls; Anti-recycle timers; Pressure regulators; Oil-level controls; Overload protection; Capacity control

Learning Objectives:
– Explain how pumpdown control operates and why pumpdown is often preferred over other methods of primary control.
– Describe the location, function, and operation of a high-pressure control.
– Name three ways to control condenser pressure and at least three ways to control system capacity.
– Explain how a differential oil pressure safety control works.
– Compare the two methods of modulating the flow of water to hydronic terminals.

Lesson 5 - Maintaining and Troubleshooting Controls


Maintaining pressure controls, thermostats, switches, valves, timers, controllers, relays, and power supplies; Troubleshooting the system

Learning Objectives:
– List the four basic steps involved in setting up a PM program.
– Explain the importance of high-pressure controls as safety devices and explain their testing procedures.
– Explain how oil pressure is maintained in various kinds of compressors.
– Describe the testing and maintenance required for condenser water regulating valves and compressor capacity controls.
– Explain how to check for oil and water contamination in control air and what measures to take to minimize them.
– Explain the major maintenance requirements of a pneumatic control system.
– Describe the maintenance required by electric and electronic controllers.
– Explain how to use a troubleshooting chart.