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All Textbook Solutions for Electricity for Refrigeration, Heating, and Air Conditioning

True or False: A heating and air-conditioning service technician can usually troubleshoot heating and air-conditioning systems without the voltage being supplied to the equipment.What is a live electrical circuit?Which of the following voltages will a refrigeration, heating, and air-conditioning technician come in contact with in the industry? a. 24 volts b. 120 volts c. 240 volts d. all of the aboveElectrical shock occurs when a person _________. a. touches an insulated wire b. touches an electric motor c. becomes part of an electric circuit d. touches a conductor that has power applied to it, but is making contact with a groundWhat are the important elements of electrical safety when working around live circuits?6RQWhich of the following is the standard by which electrical installations are measured in the United States? a. National Electrical Code b. United Electrical Code c. Basic Electrical Code d. none of the above8RQWhat type of ladder should the technician use on the job? a. aluminum b. fiberglass c. wood d. both a and b e. both b and cWhat precautions should be taken when you see a coworker receiving an electrical shock?True or False: It is recommended that at least one person on a truck know CPR.True or False: The correct fuse size for an electrical circuit is one that is sized twice as large as needed for circuit protection.What is the difference between a two-prong plug and a three-prong plug?Which prong on a three-prong plug is the ground? a. the left flat prong b. the right flat prong c. the center semicircular prong d. none of the aboveTrue or False: A grounding adapter does no good if it is not connected to an electrical ground.An electrical device that will open an electrical circuit, preventing current flow to the circuit if a small leak to ground is detected, is called a _________. a. GFCI b. common circuit breaker c. fuse d. receptacleTrue or False: Receptacles used on the job site should be protected with a GFCI.What precautions should you use when working in an area with a large number of people and you must disconnect the power from an appliance you are working on?What is the difference between a fuse and a circuit breaker?List at least five electrical safety rules that should be followed by refrigeration, heating, and air-conditioning technicians.All physical objects are composed of __________. a. substances b. matter c. neutrons d. ketonsWhat is an atom?Which of the following is a part of the atom? a. electron b. proton c. neutron d. all of the aboveWhat is static electricity?Name three ways electricity can be produced.What part do protons and electrons play in the production of electricity?Which of the following is the simplest atom that exists? a. carbon b. hydrogen c. oxygen d. sulfurWhat are the four most important characteristics of an electric circuit?What is electromotive force?Electromotive force is commonly measured in _____. a. amperes b. ohms c. volts d. wattsWhat is current?How is current measured? a. amperes b. ohms c. volts d. wattsWhat is resistance?How is resistance commonly measured? a. amperes b. ohms c. volts d. wattsWhat is electrical power?How is electrical power commonly measured? a. amperes b. ohms c. volts d. wattsWhere do electrons exist in an atom, and what is their charge?True or False: All atoms tend to lose electrons.State the law of electric charges.What is a proton? Where does it normally exist in an atom, and what is its charge?Describe briefly the method a dry cell battery uses to produce voltage.What is a conductor?Which of the following is the best conductor? a. wood b. thermoplastic c. copper d. cast ironWhat is an insulator?Which of the following is the best insulator? a. wood b. thermoplastic c. copper d. cast ironWhy do metals make the best conductors?How do electric utility companies charge customers for electricity?What is the meaning of SEER when used in conjunction with an air-conditioning unit?State Ohms law.True or False: Ohms law applies to all types of electrical circuits.What is the ampere draw of a 5000-watt electric heater used on 120 volts? a. 42 ampere b. 45 ampere c. 50 ampere d. 52 ampereWhat is the resistance of the heating element of an electric iron if the ampere draw is 8 amperes when 115 volts are applied? a. 10 ohms b. 12 ohms c. 14 ohms d. 16 ohmsWhat is the voltage of a small electric heater if the heater is drawing 12 amperes and has a resistance of 10 ohms? a. 120 volts b. 240 volts c. 60 volts d. none of the aboveWhat is the Btu/hour output of an electric heater rated at 15 kilowatts? a. 51.15 Btu/hour b. 51,150 Btu/hour c. 5115 Btu/hour d. none of the aboveWhat is the kilowatt output of an electric heater that has an ampere draw of 50 amperes if the voltage source is (a) 208 volts? (b) 240 volts?What is a series circuit?What is a control circuit?Safety devices in an electrical circuit are connected in _____ with the load.How are series circuits used in air-conditioning equipment?Why are series circuits used for most control circuits?The current draw in a series circuit is _____. a. the sum of each load in the circuit b. the same throughout the entire circuit c. divided by the number of loads in the circuit d. none of the aboveThe voltage drop of a series circuit is _____. a. the amount of voltage lost through any load b. proportional to the resistance in that part of the circuit c. equal to the voltage being applied to the circuit d. all of the aboveHow would switches used as safety devices be connected with respect to the loads they are protecting?Draw a series circuit with a thermostat, a low-pressure switch, and a high-pressure switch used as safety controls to protect a motor.Two identical 115-volt light bulbs connected in series with 240 volts would __________. a. burn dimly b. burn out immediately c. burn correctly d. none of the above11RQ12RQParallel circuits are used in the air-conditioning industry to __________. a. supply the correct line voltage to several circuits b. act as a safety circuit c. divide the voltage between two major loads d. all of the aboveWhy are parallel circuits used in the air-conditioning industry?15RQ16RQIf two 115-volt loads were connected in parallel with 240 volts, they would _____. a. burn dimly b. immediately burn out c. burn correctly d. none of the aboveWhat is a series-parallel circuit?Why are series-parallel control circuits important in the circuitry used in air-conditioning equipment?Draw a series-parallel circuit with one switch controlling two electric heaters, each being supplied with line voltage.What is the resistance of a parallel circuit with resistances of 2 ohms, 4 ohms, 6 ohms, and 10 ohms?What is the resistance of a parallel circuit with resistances of 10 ohms and 20 ohms?What is the total ampere draw of a parallel circuit with ampere readings of 2 amperes, 7 amperes, and 12 amperes?What is the voltage of a series circuit with four voltage drops of 30 volts?What is the resistance of a series circuit with resistances of 4 ohms, 8 ohms, 12 ohms, and 22 ohms?What are the three most common electric meters used in the industry?2RQWhat do most analog meters use to facilitate the needle movement? a. Ohms law b. a magnetic field that flowing electrons produce c. inductive resistance d. all of the aboveHow does an ammeter work?What are the two types of ammeters? Which type is more commonly used in the industry?6RQHow can a very small ampere draw be measured with a clamp-on ammeter?If a conductor was wrapped around the jaws of a clamp-on ammeter four times, the proper reading would be __________ if the clamp-on ammeter was reading 16 amperes. a. 16 amperes b. 8 amperes c. 4 amperes d. 2 amperesExplain the operation of an analog voltmeter.Air-conditioning or refrigeration equipment can operate properly at __________% above or below its rated voltage.11RQWhat precaution should be taken when using an ohmmeter?13RQWhat is a short circuit?15RQWhat factors should be considered when purchasing an electric meter?Match the following terms.18RQ19RQAn in-line ammeter must be connected to a circuit in _____. a. series b. parallelWhat is the difference between an analog meter movement and a digital meter movement?Give three advantages of a digital electric meter.What basic concept is used in a digital meter to calculate the circuit characteristics being measured? a. Watts law b. Volts law c. Amps law d. Ohms lawWhat is the basic accuracy of most analog and digital meters?How many digits will the 312- and 412-digit displays have?26RQThe ohmmeter differs from other types of meters in that it has its own _____ _____.Compare the digital and analog types of electric meters, giving advantages and disadvantages.What are the three types of electrical diagrams used in the heating, cooling, and refrigeration industry?A load is an electrical device that __________. a. produces electricity b. directs the flow of electricity c. assists in the starting of motors d. uses electricity to do useful workWhat is the major load of an air-conditioning system?Identify the following symbols for loads:5RQWhat do the terms normally open and normally closed refer to with regard to a switch or set of contacts? Draw a normally open and normally closed contact.What is the difference between a magnetic starter and a contactor?8RQDraw a heating and a cooling thermostat and explain the difference between them.A three-pole contactor would allow how many paths for current flow?A disconnect switch is used to __________. a. open and close the main power source to a piece of equipment b. stop and start a compressor c. control the operation of an electric heater d. open when an unsafe condition occursWhat determines whether a pressure switch opens or closes on a rise of pressure?Identify the following symbols for switches: What is the difference between a thermal overload and a magnetic overload? Draw the symbol for each.What is the purpose of a transformer? Draw the symbols for a transformer.Which of the following is not a requirement for an electric circuit? a. a source b. a path c. a load d. a signal lightWhat is the purpose of a legend on a schematic diagram?A factual diagram is _____. a. a pictorial diagram with wire colors denoted b. a combination of pictorial and installation wiring diagrams c. a combination of schematic and pictorial wiring diagrams d. none of the aboveIdentify the following symbols for safety devices.20RQTrue or False: The schematic diagram tells service technicians how to wire a system.What is the difference between a pilot duty and a line break overload?What type of switch would be used to open or close a set of contacts at a certain pressure?What is the purpose of a fuse in an electrical system?True or False: A solenoid valve is a device that opens or closes to control the flow of some element in the system.What is a signal light used for in a control system?Change the following normally open elements from the de-energized position to the energized position. Draw the symbols for the following electrical devices. a. heating thermostat b. pressure switch (closes on rise) c. heater d. motor e. solenoid coil f. normally open push-button switchAdd letter designations to the symbols to indicate the following: Draw a symbol for a magnetic starter.Why should an air-conditioning technician learn to read schematic diagrams?Briefly explain the layout of a schematic diagram.Most schematic diagrams are made up of _____. a. series circuits b. parallel circuits c. series-parallel circuits d. none of the aboveSchematic diagrams break the wiring of control systems down into a(n) _____ arrangement. a. circuit-by-circuit b. series circuit c. individual circuit d. none of the aboveDraw the symbols for the following components. a. heating thermostat b. cooling thermostat c. pressure switch (opens on rise) d. thermal line break overload e. fuse f. magnetic overload g. crankcase heater h. three-pole contactor i. relay with one NO and one NC contact j. red signal light k. three-phase compressor motorWhat is the name of an appliance that is used to remove moisture? a. humidifier b. dehumidifier c. air conditioner d. both a and cWhat is the position of the control switch if the window unit in Figure 6.14 is to operate the fan and compressor if the thermostat is closed? a. 4 and 1 b. 4, 1, and 2 c. 4, 2, and 3 d. 4 and 3 FIGURE 6.14 Schematic diagram of simple window air conditioner8RQTrue or False: The evaporator fan motor is controlled by the defrost timer in Figure 6.18.What electrical component initiates the defrost cycle of the commercial freezer shown in Figure 6.20? a. thermostat b. defrost timer c. defrost thermostat d. defrost heaterThe thermostat of the commercial freezer in Figure 6.20 is connected in series with which of the following electrical devices? a. compressor b. condenser fan motor c. evaporator fan motor d. all of the aboveWhat is the purpose of the fan switch in Figure 6.25?If the temperature in the furnace schematic shown in Figure 6.25 were to increase to an unsafe condition, what electrical device would interrupt the power supply to the gas valve? a. fan switch b. heating thermostat c. limit switch d. all of the aboveWhat is the purpose of the transformer in Figure 6.25?True or False: The system in Figure 6.28 is using a line-voltage control system.The HP and LP switches are connected in __________ with the contactor coil. a. series b. parallelThe contactor is controlled by __________. a. the disconnect switch b. the high-pressure switch c. the cooling thermostat d. none of the aboveWith the fan switch in the on position, the indoor fan will __________. a. run only when the thermostat is closed b. run when the temperature exceeds 95F c. run continuously d. none of the aboveThe compressor and condenser fan motor start __________. a. at separate times b. at the same timeThe compressor and condenser fan motor are connected in __________. a. series b. parallel21RQ22RQExplain why the lockout relay coil energizes instead of the contactor coil. See Figure 6.34.True or False: The first- and second-stage cooling will be energized at the same time when a two-stage cooling thermostat closes on a call for cooling. See Figure 6.37.True or False: A two-stage cooling thermostat would be used on a system with one condensing unit.What is the purpose of the defrost cycle of a heat pump?What two factors initiate the defrost mode in the diagram?What type of thermostat is used with the heat pump in the diagram?Explain the operation of the switchover valve and its purpose.The reversing-valve solenoid is energized on the __________ cycle. a. heating b. coolingThe defrost cycle of the heat pump schematic in Figure 6.40 is initiated by __________. a. time b. temperature c. pressure d. both b and cWhat is a pump-down system and why is it used in commercial refrigeration systems?Alternating current is __________. a. an alternating flow of electrons b. electrons reversing their flow at regular intervals c. the most commonly used current d. all of the aboveWhat is the advantage of alternating current over direct current? 3RQWhat is the common frequency of alternating current in the United States? 25 hertz 50 hertz 60 hertz none of the above 5RQ6RQ7RQ8RQ9RQ10RQ11RQ12RQ13RQ14RQHow can a 240 V/1ø/60 Hz electrical system be detected? 16RQ17RQ18RQWhat are the advantages and disadvantages of a delta electric system?20RQ21RQ22RQ23RQ24RQ25RQ1RQ2RQ3RQ4RQ5RQ6RQ7RQ8RQ9RQ10RQ11RQ12RQ13RQ14RQ15RQ16RQ17RQ18RQ19RQ20RQ21RQ22RQ23RQ24RQ25RQ26RQ27RQ28RQ29RQ30RQWhat is magnetism? 2RQ3RQ4RQHow is an electromagnet produced? 6RQ7RQ8RQ9RQ10RQ11RQ12RQWhich of the following correctly lists the motor’s starting torque from lowest to highest? capacitor start, split phase, shaded pole, three phase shaded pole, three phase, permanent split capacitor, capacitor start three phase, split phase, shaded pole, capacitor start shaded pole, split phase, capacitor start, three phase 14RQ15RQ16RQ17RQ18RQ19RQ20RQ21RQWhat is the unit of measurement for the strength of a capacitor? microamp microtorque microfarad microwatt 23RQ24RQList the five capacitor replacement rules. 26RQ27RQWhat are the advantages and disadvantages of using the following types of motors? shaded-pole motor PSC motor split-phase motor capacitor-start–capacitor-run motor 29RQ30RQ31RQTrue or False: All starting apparatuses are mounted externally to the hermetic compressor shell. 33RQWhich of the following is the capacitance of an 88-microfarad and a 108-microfarad starting capacitor connected in series? 196 microfarad 96 microfarad 48 microfarad 40 microfarad Which of the following is the capacitance of two 20-microfarad running capacitors connected in parallel? 10 microfarad 20 microfarad 30 microfarad 40 microfarad If a capacitor produces 15 ampere on a 240-volt supply, which of the following is its microfarad rating? 166 microfarad 15 microfarad 200 microfarad 3450 microfarad Which of the following capacitors could be used to replace a 35-microfarad, 370-volt running capacitor? a. 35 microfarad, 330 volt b. 35 microfarad, 390 volt c. 30 microfarad, 440 volt d. 40 microfarad, 370 volt Which of the following capacitors could be used to replace a 188-microfarad, 250-volt starting capacitor? 188 microfarad, 120 volt 259 microfarad, 120 volt 200 microfarad, 250 volt 300 microfarad, 250 volt Which of the following capacitors or combination of capacitors could be used to replace a 45-microfarad, 370-volt running capacitor? 40 microfarad, 440 volt 30 microfarad, 250 volt 30 microfarad, 370 volt 15 microfarad, 440 volt Which of the following capacitors or combination of capacitors could be used to replace an 88-microfarad, 250-volt starting capacitor? 180 microfarad, 250 volt 180 microfarad, 330 volt 150 microfarad, 120 volt 150 microfarad, 250 volt Find the common, start, and run terminals of the following hermetic compressors. Briefly explain the procedure for troubleshooting hermetic compressor motors. What are the electrical failure categories for hermetic compressor motors? What precautions should be taken when checking hermetic compressor motors? 45RQ46RQExplain the construction of an ECM. An ECM is a __________. three-phase, AC motor three-phase, DC motor single-phase, AC motor single-phase, DC motor True or False: The resistance readings of the windings of a properly operating ECM should be equal. True or False: The line voltage power supply of an ECM should never be disconnected or connected with the power on.What is the purpose of a starting relay? to start an electric motor to remove the starting winding or component from the circuit to protect the motor from starting overloads to prevent the motor from starting under heavy loads 2RQ3RQ4RQ5RQ6RQ7RQ8RQ9RQ10RQ11RQ12RQ13RQ14RQ15RQ16RQ17RQ18RQ19RQ20RQ21RQ22RQ23RQ24RQ25RQ
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