Heat Sinks:
- Specialized solid-state devices used to dissipate excess heat from components.
- Prevents overheating and potential damage to solid-state devices or systems.
Solid State Sensing Devices:
- Detect physical conditions such as temperature, humidity, and pressure.
- Common examples include thermistors and pressure transducers.
Thermistors:
- Solid-state resistors sensitive to temperature changes.
- PTC (Positive Temperature Coefficient) thermistors increase resistance with rising temperature.
- NTC (Negative Temperature Coefficient) thermistors decrease resistance with rising temperature.
- Used in various HVAC applications like motor overload protection and start assistance in motors.
Checking Thermistors:
- Use an ohmmeter and a manufacturer's resistance-temperature chart.
- Ensure correct resistance values based on ambient temperature.
- Replace if resistance is infinite or outside specified values.
Pressure Transducers:
- Convert fluid pressure into electrical signals.
- Used for applications ranging from low to high-pressure measurements in HVAC systems.
Integrated Circuits (ICs):
- Miniaturized solid-state components combining multiple transistors, diodes, and rectifiers.
- Mounted on circuit boards with metal pins.
- Found in almost all electronic equipment, including HVAC systems.
Microcontrollers and Microprocessors:
- Microcontrollers: Operate single major components, combining all necessary functions on one chip.
- Microprocessors (CPUs): Connect multiple components and manage complex system functions.
- CPUs are integral to modern HVAC systems, often involving multiple units for efficient operation.
Examples of Applications:
- Electronic Expansion Valve (EXV): Controlled by a microcontroller to maintain accurate superheat.
- Integrated Furnace Control (IFC): Manages furnace functions, including diagnostics and blower operation.
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