Esco Electrical Test Complete Questions And Answers With Latest Updates

What is current flow? - ANS D.The flow of electrons in a circuit What is impedance? - ANS A.Opposition to alternating current Like charges will - ANS B.Repel each other Any material that will readily release electrons is called: - ANS B.A conductor The symbol for current is: - ANS B. I Electricity can produce: - ANS D. All the above light heat magnetism The safety ground conductor is usually colored: - ANS B.Green An electron has: - ANS B.A negative charge Which of the following materials would be best suited for use as a semi-conductor? - ANS D.Silicon Which of the following meters must use internal power to check a load or circuit? - ANS A.Ohmmeter What would be the result if a 24 volt, 20 ohm contactor coil was wired in series with a 24 volt, 200 ohm control relay? - ANS B.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 are consumed? - ANS C. 2880 When testing a capacitor with an analog or digital ohmmeter, the meter should: - ANS B.Measure low resistance then return to a high reading How much resistance must be placed in a 120 volt circuit to limit the current to 2 amps? - ANS A.60 ohms What is resistance? - ANS A.Opposition to electron flow In electrical wiring, a black colored wire indicates: - ANS A. A hot conductor How many watts are used by a heater operating on 460 volts and drawing 5 amps? - ANS D .2300 How are fuses sized? - ANS D .Both A and B What is generally considered the maximum allowable supply voltage variation - ANS A.5% Capacitors are rated in: - ANS D .Both B and C What is the term used to describe the output side of a transformer? - ANS D .Secondary side One horsepower is equal to ______ watts. - ANS B. 746 A parallel circuit contains an 18 ohm and a 9 ohm resistor. What is the total resistance? - ANS A.6 ohms In a series circuit, the voltage drop across each load will: - ANS D .Add up to equal the source voltage Which of the following is equal to 2.1kW? - ANS c .2100 watts A capacitor analyzer is designed to check: - ANS D .The capacitance of the a capacitor On an electronic oil safety switch, what changes the pressure signal to an electrical signal? - ANS A.Transducer A three phase load requires a minimum of - ANS A.Three supply lines An electronically commutated motor (ECM) is designed to: - ANS D .Provide proper airflow under various conditions Resistance can be calculated by: - ANS A.E divided by I The total resistance in a parallel circuit will be: - ANS D .Less than the smallest resistance Which of the following statements about current is true? - ANS B.Current flow will increase when voltage increases When resistors are wired parallel: - ANS B.The voltage drop across each resistor will be the same as the applied source voltage Which of the following is equal to 100 milliamps? - ANS C. 0.10 amps The meter on a house measures the ____ passing through it. - ANS C. Watts What is the correct formula for determining wattage? - ANS A.W = E x I A parallel circuit consists of three resistors; R1 = 30 ohms, R2 = 15 ohms, R3 = 10 ohms. If the current through R2 = 4 amps, what is the source voltage? - ANS B.60 volts Three 300 ohm resistors are wired parallel. What is the total resistance? - ANS A.100 ohms Amps can be calculated by: - ANS A. E/R B.W/E C.The square root of W/R answer: D. all the above Voltage can be calculated by: - ANS C.IxR An ohmmeter should never be connected to a: - ANS D. Charged capacitor until it has been discharged Which of the following would be considered an inductive load? - ANS D. Electric motor The voltage to ground of a high leg or "stinger leg" on a three phase open delta system will be approximately: - ANS C. 208 Which of the following is the symbol for impedance? - ANS D. Z What amperage measurement would you expect if you clamped your meter around both wires in a two wire circuit? - ANS A.0 due to the cancellation of the two magnetic fields A diode is used to? - ANS A. Control the direction of electron flow Three resistors are wired parallel. Two have a value of 12 ohms, one of 6. What is the total resistance? - ANS C. 3 A transformer has 1000 turns on the primary side and 500 on the secondary. What is the output if the input is 120v? - ANS C. 60v A transformer has 1000 turns on the primary side and 2000 on the secondary. What is the output if the input is 120v? - ANS D. 240v If the conductor in an AC circuit is wound into a coil, the resulting EMF opposes supply voltage. This is called: - ANS B. Inductive reactance To change rotation on a 3-phase motor: - ANS C. Change position of any two wires A solenoid valve operates on the principle of: - ANS C. Electromagnetism A ___ is commonly used on a single phase fractional horse power compressor to disconnect the start winding. - ANS D. Current relay The rotation of a single phase motor is determined by: - ANS A.The direction of current through the start winding Single phase motor speed is determined by: - ANS B. Number of stator poles Capacitor-start, capacitor-run motors provide: - ANS B. Medium running and high starting torque Direct digital control (DDC) is: - ANS D. Electronic controls used for equipment control and monitoring What connects the T1, T2 and T3 terminals on a contactor? - ANS B. Load wires A step-up transformer increases - ANS B. voltage Utility companies usually provide residential homes with: - ANS B. 240v, single phase, three wire Transformers are rated by: - ANS B. VA at the secondary Circuit breakers and fuses are used to provide: - ANS C. Protection from an overload of current Excessive current can be caused by: - ANS D. Short circuit A device with overload protection used to control a motor is a: - ANS D. Line starter What is the minimum number of wires required between two start/stop push button controls? - ANS B. 1 If contacts become badly pitted, it is acceptable to: - ANS B. Replace the contacts or control The thermal overload contacts on a line starter are usually ___ reset. - ANS A.Manual Which of the following motors is most energy efficient? - ANS B. ECM Contactors are rated according to the maximum amperage through the: - ANS B. Contacts The ____ drawing illustrates where the components are located on the appliance. - ANS A.Pictorial On a good single phase compressor, which winding terminals have the highest resistance? - ANS A.Run to start When testing a motor with an ohmmeter, the following measurements are recorded; C to R = 4, C to S = 6.2, R to S = 10.2, R to ground = 20.4. This indicates: - ANS B. A grounded condition With a motor running at full load, voltmeter leads are placed on L1 and T1 with no measurable voltage detected. This indicates: - ANS C. Good, clean contacts When the temperature of a negative temperature coefficient (NTC) thermistor increases, its resistance: - ANS B. Decreases When the temperature of a positive temperature coefficient (PTC) thermistor increases, its resistance: - ANS A.Increases The most common type of transducer used with HVAC/R equipment creates a signal based on: - ANS D. Pressure A thermocouple can: - ANS C. Generate a small DC current To discharge a capacitor: - ANS B. Use a 15,000 to 20,000 ohm, 2 to 5 watt resistor across the terminals Which of the following is an acceptable temporary replacement capacitor for a 35MFD, 440VAC capacitor? - ANS D. 37.5MFD, 440VAC When checking the windings on a three phase motor, the resistance readings should: - ANS C. All read the same Capacitors are always connected _____ with the start winding? - ANS A. In series The symbol for a heating thermostat is represented by: - ANS C. The symbol for a pressure switch that closes on a rise of pressure is represented by: - ANS B. The symbol for a pressure switch that opens on a rise in pressure is represented by: - ANS D. The synchronous speed of a four pole, 60 Hz single phase motor is: - ANS D. 1800 RPM The symbol for a transformer is: - ANS C. The symbol for a thermal overload is: - ANS D. The symbol for a pressure switch is - ANS A. The symbol for a thermostatic switch is: - ANS B. IN the schematic, what voltage would be found across l1 to l2 ? - ANS A. 240 volts IN the schematic,(during operation ) what voltage would be found across the condenser fan motor? - ANS A . 240 volts IN the schematic,(during operation ) what voltage would be found across the transformer primary - ANS B. 240 volts In the schematic, what voltage would be found from termianl G to the load side of the transformer? (Assume the thermostat is in the closed position and the fan is set to auto.) - ANS B. 24 volts In the schematic, what voltage would be found (during operation) acros the contacts when energized in line #8? (Assume the thermostat is in the closed position and the fan is set to auto.) - ANS B. 0 volts Ine the schematic, what voltage would be be found from terminal Y to the input side of the coil on the line #11? (Assume the thermostat is in the closed position and the fan is set to auto.) - ANS A. 0 volts When troubleshooting a A/C system in the schematic, the following conditions are found. The thermostat contacts are closed. The compressor and the condenser fan motor are short cycling. The blower motor is not running . This could be caused by ? - ANS C. Afaulty blower motor or blower relay When troubleshooting a A/C system in the schematic, the following conditions are found. The thermostat contacts are closed. The compressor and the condenser fan motor are not running. The blower motor is running . This could be caused by ? - ANS C. the hp,lp,overloads, oil pressure switch are open - ANS C. a faulty thermostat- auto / fan on switch In the schematic, the crankcase heater will operate; - ANS C. when the compressor is off IN the schematic,, the coil on line # 11 does not control; - ANS D. the blower motor