Unit 13

The automatic control of a system is intended to ____.

• maintain stable or constant conditions without excessive human interference
• maintain the working conditions of the equipment with a controllable device
• evaluate overloading situations
• maintain safe operations for service technicians

Modulating controls are used to ____.

• vary the speed of a motor
• start motors
• stop motors
• stop the flow of a liquid

When a control is required to control space or product temperature, it is called a ____.

• thermostat
• safety device
• pressure control
• speed control

A thermal system overload may occur if a specific electrical or mechanical component is not cooled properly, resulting in ____.

• overheating
• underload
• failure
• stagnation pressure

Devices, such as thermostats, that open and close their contacts during the ____ operation of the system are referred to as operational controls.

• normal
• initial
• final
• most recent

The compressor in the refrigerator has a protective device that keeps it from overloading and damaging itself. This device is called a(n) ____.

• overload
• capacitor
• mass control
• speed control

The metals most often used in a bimetal temperature control are ____.

• brass and steel
• copper and brass
• copper and steel
• brass and aluminum

An example of a bimetal device is a ____.

• snap-disc
• mercury-filled tube and diaphragm
• thermistor
• Bourdon tube

The Bourdon tube ____.

• straightens out with an increase in vapor pressure
• straightens out with an increase in voltage
• curls inward with an increase in vapor pressure
• straightens out with an increase in electrical current

A thermocouple is a device that ____.

• converts heat to electrical energy
• converts heat to mechanical movement
• converts heat to fluid flow
• couples two temperature controls together