NATE Electrical Controls Exam Questions and Complete Solutions Graded A+

A fuse is used in an electrical circuit to - Answer: Protect the circuit wires from an overcurrent condition How are fuses rated - Answer: In amps with a maximum voltage rating What will an ohmmeter measure when testing an open fuse - Answer: Infinite resistance What type of sensing element is commonly found in fan and limit controls - Answer: Bimetal What is used to sense space temperature in electronic temperature controls - Answer: Thermistors What is known about a liquid-charged remote-type temperature control - Answer: Its bulb is both extremely sensitive and completely full of liquid When installing the gas-charged remote temperature control - Answer: Its sensing bulb must always be the coldest part of the control A temperature control that uses a positive temperature coefficient thermistor (PTCT) - Answer: Increases resistance as temperature increases A heating thermostat - Answer: Opens on a rise in temperature The heat anticipator - Answer: Controls system overshoot When adjusting a heat anticipator on a thermostat - Answer: The heating control amperage must be measured The correct color code and its circuit for a heating and cooling thermostat - Answer: Red-power source, Yellow-cooling circuit, White-heating circuit, Green-fan relay How many wires does a two-stage heating and two-stage cooling thermostat commonly use - Answer: 6 What is the purpose of automatic changeover on a heating and cooling thermostat - Answer: It automatically changes from heating to cooling What is the definition of a deadband - Answer: Deadband is the point at which the thermostat is satisfied when in the automatic cycle An outdoor thermostat that is used on an electric heating system is commonly used to - Answer: Energize electric heaters if the outdoor temperature drops below a predetermined temperature A cooling thermostat - Answer: Opens on a drop in temperature A cooling anticipator - Answer: Controls system lag Outdoor thermostats are used on A/C systems to - Answer: De-energize the compressor during low ambient conditions What type of sensing element is the most accurate - Answer: A thermistor What is known about the anticipators that are located on a programmable thermostat - Answer: The heating either has a fixed setting, or adjustable; cooling has a fixed setting On a heat pump type programmable thermostat what cycle uses an LED light - Answer: The emergency heat cycle When installing a programmable thermostat, what extra low-voltage wire is commonly added to the circuit - Answer: The common from the transformer How does a two-stage therostat control a heat pump during the heating cycle - Answer: The compressor is controlled by the first stage, and the auxilliary hreaters are controlled by the second stage What is a battery used for on a programmable thermostat - Answer: To save the system's program if there is a loss of power In a programmable thermostat what is "temperature setback" - Answer: It is the temperature setting of the thermostat during an unoccupied time What is meant by the term "intelligent recovery" - Answer: It is the gradual return of space temperature to the system's set point after a system setback What is the purpose of the limit control on a heating system - Answer: It de-energizes the gas valve if the temperature of the heat exchanger becomes excessive The limit switch that is used on a forced-air gas-fired furnace is commonly - Answer: A closed bimetal switch A limit switch that is used on a forced-air gas-fired furnace - Answer: Can be automatic or a manual type of a reset The purpose of low-pressure switch in A/C system - Answer: It breaks the circuit to the compressor if the low-side pressure drops too low The low-pressure switch will - Answer: Close on a rise in pressure and open on a drop in pressure The purpose of high-pressure switch in A/C syste