Exam Bruhh Flashcards
(26 cards)
Parrallel Series receive all bolts of pressure.
In series bulb does not get all 240 volts.
Bimetal devices
Snap disk
Bourdon tube
This tube is often used in the same manner as the diaphragm and the bellows to monitor fluid expansion
Detent means
Snap action
Thermacouple
Does not use expansion to control thermal change and study uses electrical principlesAlso consist of two unlike metals joining together at one end
Thermistors
Vary their resistance Two current flow based on its temperature thermistors are incorporated into solid state circuit boards and respond to small temperature changes
Thermopiles
Multiple thermistors can be wired in series with each other to provide a higher output voltage and one configure like this are called thermopiles
Heat anticipator- is a small resister which is usually an adjustable located close to the bimetal sensing element. Is in series
A cold anticipator is a fixed resistor in a space coin thermostat used to start an air-conditioning system prematurely
The heating thermostat opens on a rise in temperature
Detent is a snap action.
An example of an electro mechanical control is a high pressure switch
An
Example of a mechanical control is a water pressure regulating valve
Cooling thermostats may have a cold calling anticipator in parallel with the thermostat contacts
Low voltage thermostat passes power from the transformer to the Loads in the control circuit
High pressure transducer is a device that senses the pressure in the system and then converts the sensed pressure signal to an electronic signal usually to be processed by microprocessor
Motor protection- Bimetal and thermistor.
Suction gas cools hermetic compressor
Some electromechanical controls are low pressure cut out, high-pressure cut out, and thermostats.
Examples of mechanical controls Are water regulating valve, pressure relief valve, and expansion valves.
Solid state boards allow for resistance to change with temperature
Low-pressure high-pressure is not a mechanical control
Differential equals average box temperature
Cool anticipator replace with new thermostat
Typical Pressure to gas furnace 3.5
Water cooled system valve is acting against system head pressure feeds into a water regulator on condensing side.
Bimetal temp Control brass and steel
Differential settings cut in and cut out
Automatic control system- Maintain controllable conditions.
Controllable devices- Compressor gas regulator
Two loads on energy side fan motor and light two speeds
F equals single pole double throw
FH equals time on time off
SD = Service disconnect manual, (c) contact coil turns on compressor. LS - opens when The furnace is too hot
Cool off heat system switch
Heating opens on rise, cooling closes on rise
Auto on= Fan Switch
GU has one limit switch
Tc and Tt are switches, Time on temperature up. This schematic is for heating and cooling
No compressor= no outdoor fan motor
Anticipator’s for cooling are in parallel, while the heat anticipator is in series
