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HVAC/R ELECTRICITY FINAL EXAM
STUDY GUIDE
A
The symbol for current is; ... E. I. R. W. - CORRECT ANSWER-B Which of the following materials would be used as a semi-conductor? ... Aluminum Copper Mercury Silicon - CORRECT ANSWER-D The color of the safety ground wire is usually; ... black or white. green or bare. red or white. white or bare. - CORRECT ANSWER-B An electron has: ... a negative charge. a neutral charge. A positive charge. no charge. - CORRECT ANSWER-A Resistance is; ... electrical pressure causing voltage flow. enabled amperage flow. opposition to alternating current only. opposition to current flow. - CORRECT ANSWER-D How many watts of power are used by a heater operating at 460-volts and drawing 5- amps?
5 watts 92 watts 460 watts 2,300 watts - CORRECT ANSWER-D Cooling anticipation is performed by the thermostat; ... during the off cycle. during the on cycle. in minutes of compressor off time. minutes squared of compressor run time. - CORRECT ANSWER-A In electrical wiring, a black colored witre in an aemating curent crout usualy indicates the: ... ground conductor. hot conductor. neutral conductor. safety ground. - CORRECT ANSWER-B Current flow is the; flow of voltage in a circuit. flow of electrons in the circuit. impedance of a circuit. inductive reactance of the circuit. - CORRECT ANSWER-B Impedance is the measurement of the; ... amperage in a circuit. electrical pressure in a circuit. opposition to the flow of alternating current through a circuit. voltage applied to the circuit. - CORRECT ANSWER-C Like charges; ... are negative. are positive. attract one another. repel each other. - CORRECT ANSWER-D Any material that will readily release electrons is called a/an; ... conductor.
4 - CORRECT ANSWER-B
What term is used to describe the output side of a transformer? ... High inductive side Low inductive side Primary side Secondary side - CORRECT ANSWER-D One horsepower is equal to; ... 3.415 watts. 208 watts. 746 watts. 1,200 watts. - CORRECT ANSWER-C How much resistance must be placed in a 120-volt circuit to limit the current to 2 amps? ... 60 ohms. 118 ohms 120 ohms 240 ohms - CORRECT ANSWER-A A parallel circuit contains an 18-ohm and 9-ohm resistor. The total resistance equals; ... 6 ohms 8 ohms. 10 ohms 27 ohms. - CORRECT ANSWER-A In a series circuit, the voltage drop acros each resistance (a) will; ... add up to equal the source voltage. add up to the total resistance. depend on the current to each resistor. depend on the wire gauge. - CORRECT ANSWER-A The total resistance of a parallel circuit will be; ... equal to the largest resistance equal to the smallest resistance. less than the smallest resistance. the sum of all resistances. - CORRECT ANSWER-D
Current flow will increase when; ... current flow is the same as voltage. resistance increases. voltage decreases. voltage increases. - CORRECT ANSWER-D When resistors are wired in parallel the; ... current through any one resistor will be the same as the total circuit current. total resistance is determined by adding the values of each resistor. voltage drop across each resistor will be the same as the applied source voltage. voltage drop across each resistor will depend on the value of each resistor. - CORRECT ANSWER-D 2.1 kilowatts (KW is equal to; ... 21 watts. 210 watts. 2,100 watts. 21,000 watts. - CORRECT ANSWER-C A Wi-Fi thermostat communicates with the network by the; ... name assigned to the thermostat by the contractor. name of the thermostat from the manufacturer. thermostat's IP and/or Mac address. thermostat's model and serial number. - CORRECT ANSWER-C A capacitor analyzer is designed to measure the; ... capacitance of a capacitor. capacitive resistance of a capacitor. capacitor voltage percentage of leakage. - CORRECT ANSWER-A Which device changes the pressure signal in an electronic oil safety switch to an electrical signal? ... Electronic processor The bellows The circuit board Transducer - CORRECT ANSWER-D Heatng anticipation is performed by a mechanical thermostat; ...
WIE. - CORRECT ANSWER-A
Voltage can be calculated by; ... I/R. Ix R R/I. W/R. - CORRECT ANSWER-B A multimeter set to measure resistance should never be connected to a/an; ... charged capacitor until it has been discharged coil or a winding of a compressor. motor that has a grounded condition. resistor until it has been checked by other means. - CORRECT ANSWER-A Which of the following would be considered an inductive load? ... electric heat strip electric motor solid state relay start capacitor - CORRECT ANSWER-B The voltage to ground of a "High leg" on a three-phase open Delta system will be approximately ... 120 208 220 240 - CORRECT ANSWER-B A transformer has 1,000 turns of wire in the primary coil and 500 turns in the secondary coil. If 120-volts are applied, the output voltage will be; ... 60 volts. 120 KV 240 volts. 620 volts. - CORRECT ANSWER-A A transformer has 1,000 turns of wire in the primary coil and 2000 turns in the secondary coil. If 120-volts are applied, the output voltage will be; ... 60 volts. 120 KV 240 volts. 620 volts. - CORRECT ANSWER-C
Which of the following letter is the representation for impedance in an AC circuit? ... W X Y Z - CORRECT ANSWER-D When current lows in a two-wire circuit (such as 120 volts) if a camp on amp meter is clamped around both wires what measurement would you expect? ... Double the amps due to reversing the magnetic field, Half the amperage due to reversing the magnetic field. The same reading as a one wire circuit. Zero amps due to cancellation of the two fields. - CORRECT ANSWER-D If the conductor in an AC circuit is wound into a coil, the resulting EM opposes the supply voltage This opposition is called; ... capacitive reactance. Conductance. inductive reactance. influence. - CORRECT ANSWER-C A diode is used to; ... control the direction of electron flow. convert DC current to AC current. increase or decrease frequency. increases inductive reactance. - CORRECT ANSWER-A What can be done to provide a common wire to an electronic thermostat when the existing cable cannot be replaced or when an additional wire cannot be installed? ... A diode and a DC capacitor are wired in series with the fan circuit and the common terminal. A diode and an AC capacitor are wired in series with either the heating or cooling circuit and the common terminal. The common is made through the "C" terminal on the system compressor. An add-a-wire accessory can be used to take the place of terminals "y" and "G" - CORRECT ANSWER-D The direction of rotation of a single-phase induction motor is determined by the; ... direction of current flow through the run winding. direction of current flow through the start winding.
When checking the windings of a three-phase motor; ... all three terminals should show different readings. all three terminals should show the same resistance. the pair of windings with the highest resistance will indicate the other is common. the resistance of one winding should be the sum of the other two - CORRECT ANSWER-B When testing the windings of a single-phase motor, the; ... common to run terminals will show the lowest resistance. common to start terminals will show the lowest resistance. pair of terminals with the highest resistance will indicate that the other terminal is the start. start to run terminals will show the lowest resistance. - CORRECT ANSWER-A A direct digital control (DDC) is a/an; ... digital control for controlling the electron flow in a series circuit. digital control for controlling the electron flow in a parallel circuit. electronic control that must be manually adiusted. electronic control used for equipment operation and monitoring. - CORRECT ANSWER- D A step-up transformer increases; ... amperage. power. resistance. voltage - CORRECT ANSWER-D Transformers are rated according to; ... ohms at the primary. ohms at the secondary. volt-amps (VA) at the primary: volt-amps (VA) at the secondary. - CORRECT ANSWER-D How many diodes are used to make a bridge rectifier connected to a 2-wire transformer? ... 1 2 3 4 - CORRECT ANSWER-D
What connects to teminals 1, T2, & T3 on a contactor or motorstater? ... Coil connections and ground Load connections. Power supply connections Start / stop leads - CORRECT ANSWER-B Circuit breakers and fuses are primarily used for; ... protection from an overload of current. protection of over impedance to a condensing unit. C protection of impedance for inductive loads. switches used as protection devices. - CORRECT ANSWER-A Excessive current can be caused by; ... an open circuit. a short circuit. an undersized fuse. oversized wiring. - CORRECT ANSWER-B A device with overload protection used to control a motor is a; ... direct on-line starter. motor relay. remote sensing contactor. selenium rectifier. - CORRECT ANSWER-A Relays are generally used to control inductive loads ranging between; ... 1 - 15 amps 16 - 30 amps. 31 - 50 amps 51 - 100 amps. - CORRECT ANSWER-A Contactors are rated according to the maximum amperage through the; ... Coil Contacts Fuse Thermostat - CORRECT ANSWER-B What is the minimum number of wires required between two mechanical start/stop push button controls? ... 1
good safety ground. grounded condition. locked rotor condition. open in the winding. - CORRECT ANSWER-B With a motor running at full load, voltmeter leads are placed on L1 and T terminals of the contactor. The voltmeter indicates no measurable voltage. This is an indication of, ... excessive resistance in the contacts. good clean contacts no voltage to the motor. this is not a valid test. - CORRECT ANSWER-D When the temperature of a negative temperature coefficient (NTC) thermistor increases, its resistance will; ... Decrease. Increase increase proportionately to the Delta T. remain the same - CORRECT ANSWER-A When the temperature of a positive temperature coefficient (PTC) thermistor increases, its resistance will; ... decrease. increase. increase proportionately to the Delta T. remain the same. - CORRECT ANSWER-B The most common type of transducer used with HVAC equipment creates a signal based on; ... pressure the specific gravity of the refrigerant. Time turbulence. - CORRECT ANSWER-A A thermocouple can; ... be used to power a shaded pole motor. generate a small AC electrical current. generate a small DC electrical current. generate up to 1 volt. - CORRECT ANSWER-C To discharge a capacitor prior to testing with a digital multimeter;
touch the terminals with your bare fingers. use a screwdriver across the capacitor terminals use a 15,000 or 20,000 ohm, 2 to 5-wait resistor across the terminals. use a 5,000 ohm, 2 to 5-watt resistor across the terminals. - CORRECT ANSWER-C How is the common on electronic thermostats obtained when there are only 4 wires (R, G, W, and Y) from the old heating and cooling thermostat? ... The common is made through the back EMF of the fan relay circuit. The common is made through the cooling circuit when the thermostat is et for cooling and through the heating circuit when the thermostat is set for heating The common is made through a diode and DC capacitor wired in series with the indoor fan relat The thermostat references common through an inactive circuit - CORRECT ANSWER- D The synchronous speed of a two pole, 60-Hz single-phase motor is; ... 1500 гр 1800 гр 3450 гр 3600 гр - CORRECT ANSWER-D Referring to the diagram, which is the symbol for a heating thermostat? ... A B C D - CORRECT ANSWER-B Referring to the diagram, which is the symbol for a pressure switch that closes on pressure rise? ... A B C D - CORRECT ANSWER-A The symbol for a pressure switch that opens on pressure rise is represented by diagram ... A B C D - CORRECT ANSWER-C
0 volts 120 volts 240 volts 480 volts - CORRECT ANSWER-A In the schematic, what voltage would be found from terminal Y to the output side of the coil on line #11? ... 0 volts 120 volts 240 volts 480 volts - CORRECT ANSWER-B When troubleshooting the A/C system in the schematic, the following conditions are found. The thermostat contacts are closed. The compressor and condenser fan motors are short cycling. The blower motor is not running. This could be caused by; ... a blown fuse on line #10. a faulty blower motor or blower relay. a faulty coil on line # an open transformer. - CORRECT ANSWER-B When troubleshooting the A/C system in the schematic, the following conditions are found. The thermostat contacts are closed. The compressor and condenser fan are not running. The blower motor is running. This could be caused by; ... a de-energized BR (line 8). an energized CCH. an energized contactor coil (line #11). an open HP, LP, overloads, or oil pressure switch (line #11). - CORRECT ANSWER-D When troubleshooting the AVC system in the sond condenser fan motors are shotowing conditions are found. The thermostat contacts are closed. The compressor and confrom ere Autolors are short cycling. The blower motor is not tumming. When the fan switch at the thermostat is moved from the AUTO position to the FAN ON position, the blower runs. This could be caused by; ... a blown fuse on line # 10. a faulty blower relay coil. a faulty contactor. a faulty thermostat - AUTO / FAN ON switch. - CORRECT ANSWER-D In the schematic, the crankcase heater will operate; ... at all times.
when the compressor is off. when the compressor is on. when the oil pressure switch is on. - CORRECT ANSWER-B In the schematic, the coil on line #11 does NOT control; ... the blower motor. the compressor. the condenser fan motor. the crankcase heater. - CORRECT ANSWER-A In the schematic, the coil on line #12 controls the; ... blower motor relay. fan switch. thermostat. transformer. - CORRECT ANSWER-A In the schematic, if the fuse in L2 is blown the; ... blower motor will continue to operate. blower motor will single phase and burn-out. compressor will continue to operate. transformer will be de-energized - CORRECT ANSWER-A
