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HVAC Excellence - ELECTRICITY Exam with
100% Correct Answers.
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 be best suited for use as a semi- conductor? - Correct answer silicon The safety ground conductor is usually color coded; - Correct answer green or bare. 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 240 volts and drawing 5 amps? - Correct answer 1200 watts Which of the following meters must use its internal power to check a load or circuit? - Correct answer Ohmmeter In electrical wiring, a black colored wire in an alternating current circuit usually indicates; - Correct answer the hot conductor. Fuses are sized by: - Correct answer Volts & Amps
What would be the result, if a 24 volt, 20-ohm low voltage conta ctor coil were wired in series with a 24 volt, 200-ohm control relay coil? - Correct answer Only the control relay would operate. 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 Which of the following is generally considered to be within 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 or digital ohmmeter, the meter should; - Correct answer measure low resistance then return to high reading. What is the term used to describe the output side of a transformer? - Correct answer Secondary side. One horsepower is equal to __________ watts. - Correct answer 746 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 a 18 ohm and a 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
The voltage to ground of a "high Leg" or "Stinger Leg" on a three phase open Delta system will be approximately; - Correct answer 208 A transformer has 1000 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 1000 turns of wire in the primary coil and 2000 turns in the secondary coil. If 120 volts are applied, the output voltage will be; - Correct answer 240 volts Which of the following is the symbol for Impedance in an AC circuit? - Correct answer Z When current flows in a two wire circuit (such as 120 volts) if a clamp on amp meter is clamped around both wires. What measurement would you expect? - Correct answer Zero amps due to cancelation of the two fields. If the conductor in an AÇ 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 capacitor start 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. Direct Digital Control (DDC) is - Correct answer electronic controls use for equipment operation and monitoring 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, three wire What connects to the terminals T1, T2, & T3 on a contactor or motor starter? - Correct answer Load connections Circuit breakers & fuses are primarily used to provide; - Correct answer protection from an overload of current. Excessive current can be caused by; - Correct answer short circuit. A device with overload 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 10
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 heating thermostat is represented by diagram. - Correct answer B The symbol for a pressure switch that closes on pressure rise represented by diagram - Correct answer A The symbol for a pressure switch that opens on pressure rise 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 O 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 # with the thermostat closed? - Correct answer 0 volts. In the schematic, what voltage would be found from terminal G to the load side of the transformer? - Correct answer 0 volts In the schematic, what voltage would be found across the contacts when energized in line #8 - Correct answer 0 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 crankcase heater will operate; - Correct answer when the compressor 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, if the fuse in L2 is blown the. - Correct answer blower motor will continue to operate. In the schematic, with the thermostat bulb closed, what voltage would be found from Terminal Y to the Common side of the Contactor Coil on Line #11? - Correct answer 24 Volts
