HVAC Electrical Test Exam Questions with 100% Correct Answers for 2024., Exams of Electrical Engineering

Download HVAC Electrical Test Exam Questions with 100% Correct Answers for 2024. and more Exams Electrical Engineering in PDF only on Docsity!

HVAC Electrical Test Exam Questions with 100% Correct

Answers for 2024.

Current flow is - Correct answer the flow of electrons in the circuit Impedance is - Correct answer opposition to alternating current flow Like charges - Correct answer repel each other Any material that will readily release electrons is called - Correct answer a conductor The symbol for current is - Correct answer I Which of the following materials would best be suited for use as a semi-conductor

• Correct answer silicone The safety ground conductor is usually color coded - Correct answer black (or bare or green & yellow stripe) An electron has - Correct answer a negative charge Resistance is - Correct answer opposition to current flow How many watts of power are used by a heater operating at 460 volts and drawing 5 amps? - Correct answer 2300 watts What type of meter uses its own battery? - Correct answer ohmmeter In electrical wiring a black colored wire usually indicates - Correct answer the hot conductor Fuses are sized by - Correct answer Volts & Amps Two 120 volt incandescent light bulbs are wired in series, one is a 60 watt bulb, and the other is a 4 watt bulb. The result would be; - Correct answer both bulbs light Three defrost heaters; each 15 ohms are wired in parallel to a 120 volt power supply. How many watts of power will be used? - Correct answer 2880 watts What is generally considered to be the maximum allowable (plus or minus) supply voltage variation? - Correct answer 5% Capacitors are rated in: - Correct answer Microfarads & Volts When testing a capacitor with an analog ohmmeter, the needle on the meter should; - Correct answer deflect towards zero then return to infinite reading.

What is the term used to describe the output side of a transformer? - Correct answer Secondary side One horsepower is equal to how many watts? - Correct answer 746 Watts How much resistance must be placed in a 120 volt circuit in order to limit the current to 2 amps? - Correct answer 60 ohms A parallel circuit contains an 18 ohm and 9 ohm resistor. The total resistance equals; - Correct answer 6 ohms In a series circuit, the voltage drop across each resistance (load) will; - Correct answer Add up to equal the source voltage The total resistance of a parallel circuit will be; - Correct answer less than the smallest resistance Which of the following statements about current is true? - Correct answer Current flow will increase when voltage increases. When resistors are wired in parallel; - Correct answer the voltage drop across each resistor will be the same as the applied source voltage. Which of the following is equal to 2.1KW? - Correct answer 2,100 Watts Which of the following is equal to 100 milliamps? - Correct answer 0.10 amperes A capacitor analyzer is designed to read; - Correct answer the capacitance of a capacitor A 240 volt, 3 wire circuit can be split into two 120 volt circuits. - Correct answer TRUE The electric meter on a house measures the _______ passing through it. - Correct answer wattage A three phase load requires a minimum of; - Correct answer three supply lines Which of the following is the correct formula for determining wattage in an electrical circuit? - Correct answer W = E times I (or V x I) A parallel circuit consists of three resistors R1=30 ohms R2=15 ohms R3=10ohms If the current through R2=4 amperes, what is the source voltage? - Correct answer 60 volts The 300 ohm resistors are wired in parallel. The total resistance equals; - Correct answer 100 ohms

An electronically commutated motor (ECM) is Designed to - Correct answer provide proper air flow under various conditions. Resistance can be calculated by - Correct answer E divided by I (R = E/I) Voltage can be calculated by - Correct answer I times R An ohmmeter should never be connected to - Correct answer a live circuit Which of the following would be considered an inductive load? - Correct answer electric motor The voltage to ground of a "high leg" on a three phase open Delta system will be approximately; - Correct answer 208 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; - Correct answer 60 volts A transformer has 1,000 turns of wire in the primary coil and 2,000 turns in the secondary coil. If 120 volts are applied, the output voltage will be; - Correct answer 240 volts Which of the following is NOT a factor in determining impedance in an AC circuit?

• Correct answer frequency When current flows, a ______________ is produced around the conductor. - Correct answer magnetic field If the conductor in an AC circuit is wound into a coil, the resulting EMF opposes the supply voltage. This opposition is called; - Correct answer inductive reactance A diode is used to; - Correct answer Control the direction of electron flow. A _____________ is commonly used on a single phase fractional horse power compressor motor to disconnect the start winding after the motor starts - Correct answer Current relay Direction of rotation of a single phase induction motor is determined by; - Correct answer the direction of current flow through the start winding. Single phase motor speed is determined by the; - Correct answer number of stator poles The capacitor start-capacitor run (CSCR) motor provides; - Correct answer high starting and running torque To change direction of rotation of a three phase motor; - Correct answer change the position of any two supply wires

Capacitors are always connected __________ to the start winding - Correct answer in series Which meter is used to bench check a motor for shorts or open windings? - Correct answer ohmmeter A solenoid valve coil operates on the principle of; - Correct answer Electromagnetism When checking the windings of a three phase motor; - Correct answer all three terminals should show the same resistance When testing the windings of a single phase motor, - Correct answer the common to run terminals show the lowest resistance Technician #1 says that an OPEN transformer coil is indicated by a reading of infinity on an analog ohmmeter. Technician #2 says that a SHORTED transformer coil is indicated by a reading of infinity on an analog ohmmeter. - Correct answer Technician #2 only A step up transformer increases; - Correct answer voltage Transformers are rated according to; - Correct answer VA at the secondary Utility companies usually supply residential homes with ___________ service. - Correct answer 240V, single phase, and three wire The terminals T1, T2, & T3 are located at the _______ of a contactor. - Correct answer Top Circuit fuses and breakers are primarily used to protect; - Correct answer loads Excessive can be caused by; - Correct answer short circuit A device with over load protection used to control a motor is a; - Correct answer line starter Relays are generally used to control inductive loads up to ______ amps. - Correct answer 25 Contactors are rated according to the maximum amperage through the; - Correct answer contacts What is the minimum number of wires required between two Start/Stop push button controls? - Correct answer 3 If contacts become badly pitted, it is acceptable to; - Correct answer replace the contacts or control

The thermal overload contacts on a line starter are usually __________ reset. - Correct answer manual The __________ drawing illustrates where the components are located in small appliances. - Correct answer pectoral Which of the following motors is most energy efficient? - Correct answer ECM In a single phase motor, which winding has the most resistance? - Correct answer start When testing a motor with an ohmmeter, the run winding shows 1,000 ohms to the motor frame. This indicates; - Correct answer a grounded condition With a motor running at full load, voltmeter leads are placed on L! And T terminals of the contactor. The voltmeter indicates no measurable voltage. This is an indication of; - Correct answer good clean contacts When the temperature of a negative temperature coefficient (NTC) thermistor increases, its resistance will; - Correct answer decrease When the temperature of a positive temperature coefficient (PTC) thermistor increases, its resistance will; - Correct answer increase A transducer can create a signal based on; - Correct answer pressure A typical thermocouple used on a gas furnace can - Correct answer Generate a small DC electrical current To discharge a capacitor prior to ohmmeter testing; - Correct answer use a 20,000 ohm, 2 to 5 watt resistor across the terminals. Which of the following is an acceptable temporary replacement for a run capacitor rated at 35MFD @ 440VAC; - Correct answer 37.5MFD @ 440VAC The synchronous speed of a four pole, 60 Hz single phase motor is; - Correct answer 1800 rpm The symbol for a transformer is represented by diagram ______ - Correct answer B The symbol for a thermal overload is represented by diagram ______ - Correct answer A The symbol for a pressure switch is represented by diagram ______. - Correct answer C In the schematic, what voltage would be found across L1 to L2? - Correct answer 240 volts

In the schematic, what voltage would be found across the condenser fan motor? - Correct answer 0 volts In the schematic, what voltage would be found across the transformer primary? - Correct answer 240 volts In the schematic, what voltage would be found across the fuse in line #10? - Correct answer 0 volts In the schematic, what voltage would be found from terminal R to terminal G on the thermostat? - Correct answer 24 volts In the schematic, what voltage would be found across the contacts in line #8? - Correct answer 240 volts In the schematic, what voltage would be found from terminal Y to the input side of the coil on line #11 - Correct answer 0 volts? In the schematic, what voltage would be found from terminal Y to the output side of the coil on line #11 - Correct answer 0 volts? 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; - Correct answer a faulty blower motor or blower relay. 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; - Correct answer The HP, LP, overloads, or oil pressure switch are open (line #11). 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. 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; - Correct answer a faulty thermostat - AUTO/FAN ON switch In the schematic, the crank case heater will operate; - Correct answer when the compressors is off In the schematic, the coil on line #11 does NOT control; - Correct answer the blower motor In the schematic the coil on line #12 controls the; - Correct answer blower motor relay In the schematic, in the fuse in L2 is blown the; - Correct answer blower motor will continue to operate