101 Questions
What is the minimum recommended transformer rating to properly operate a 2HP (horsepower) 3-phase motor at 230 volts?
3 kVA
What is the standard power factor commonly considered for the 3-phase generators used in large commercial environments?
0.8
What is the recommended welding process for use in underground circuit connections?
Exothermic
What is the standard height of grounding rods commonly available in the market?
8 ft. to 10 ft.
Which of the following service points must be directly connected to a grounding electrode?
All of the above
Which of the following materials are commonly used in the construction of grounding rods?
Copper, Copper-Clad Steel, Stainless Steel
Which one of the following operations is NOT associated with the functions of an electrical transformer?
Improves power factor
What is the most common voltage on the commercial 3-phase generator sets normally used in the industry?
480 Volts
Which of the following are the major types of equipment grounding schemes?
Clean, Dirty, Structural
Which of the following statements is false regarding a grounding connection?
Always paint first and then install the connection
Which of the following ratios of power de-rating will occur, if you convert a 3-phase generator to a single-phase generator through a phase conversion mechanism?
30%
How many types of excitation are commonly used in generators?
2 Types
Which of the following arrangements is commonly used for the improvement/correction of the power factor of an electric motor?
A parallel capacitive load
Which of the following are two major types of 3-phase transformer connections commonly used in the industry?
Wye & Delta
Normally, what is the ratio of starting current for a 3-phase motor?
400%–1000% of full load current
Which of the following types of induction occurs in the secondary winding of a transformer due to a revolving magnetic field in the primary winding?
Mutual induction
Which of the following conductors should be neither switched nor fused in an electrical power system?
Neutral conductor
Which of the following statements is NOT true about a neutral point in an alternating current electrical system?
The common point of a 3-phase/3-wire delta connection
Which of the following factors is related to the over-excitation problem commonly observed in generators?
All of the above
What is the phase difference between the three windings of a 3-phase induction motor?
120 electric degrees
What is the function of a diode bridge installed on an electrical generator?
Conversion of AC power
What are two main types of encoders commonly used on commercial motors for motion control?
Linear & Rotary
Which of the following arrangements do NEC standards warrant for a transformer that has only primary overcurrent protection?
Proper bonding and grounding of transformer
Which of the following pairs of color codes is recommended by the NEC for neutral conductors?
Gray & White
Which of the following types of motors will require an additional starting mechanism?
Synchronous motor
Which of the following pole numbers are commonly used in synchronous motors in the industry?
2, 4, 6
What is the minimum gauge required for copper bonding conductors used in a system with a maximum overcurrent protection of 100 Amperes?
8 AWG
Which of the following statements is true about an electric motor?
It converts electrical energy to mechanical energy
If the increase in voltage output of a generator is held constant through auto voltage regulator settings while changing the frequency from 50 Hz to 60 Hz, what will be the impact on output power?
It will increase by 5%
The center tap of the secondary winding of a split-phase transformer is connected to:
Grounded neutral
What is the recommended size of aluminum grounding conductor required for electrical equipment, which is installed with 600-ampere overcurrent protection?
2/0 AWG
What is the maximum allowable ratio of conduit fill for an existing conduit?
40%
What is the range of energy loss in different types of electrical transformers?
2% to 5%
Which of the following voltages is carried by smaller legs of commercial transformers in the electric industry?
120 volts
Which of the following activities is not related to routine maintenance of a standby diesel generator?
No-load testing
Which of the following voltages is carried by the wild leg of a commercial transformer?
208 volts
Which of the following applications does NOT use an induction motor?
Paper mill
According to NEC's definition, which of the following statements is false regarding a tap conductor?
It is a service conductor
What minimum gauge of wire is recommended for connecting a 2 HP 3-phase motor (230/460 volts) located 100 feet away from the transformer?
12 AWG
What is the minimum recommended width of the copper grounding strip for equipment grounding?
3.5”
Which of the following line-to-line (phase-to-phase) voltage ratios is correct for Y-connected three-phase transformers?
1.73 times of a line-to-neutral voltage
Which of the following conditions is required for concrete encasement when using PVC conduit for wiring electric equipment in Class I hazardous locations?
At least 2” concrete thickness & 24” cover from the grade to conduit top
Electrical motors can be found in all of the following applications except:
Expressway
Which of the following problems will occur, if the prime mover of any one of the two generators operating in parallel/synch fails?
Reversal of power will occur in the faulty generator
What is the maximum resistance of a single rod, plate, or pipe used as a grounding electrode?
25 Ohms
Which of the following types of wires is commonly used to handle 110–600 volts in wet as well as dry conditions?
All of the above
According to the NEC, a transformer containing liquid that can burn is required to be installed _____________ in Class I/Division I locations.
In a closed vault
What is the minimum recommended size of spare conduit while laying cable conduits from a transformer to power distribution system panels?
2”
Which of the following is NOT a part of a 3-phase induction motor?
Slip ring
What is the minimum recommended distance between two rods, plates, or pipes when using a two-rod grounding electrode?
6 feet
Which of the following parameters is tested and verified through Megger testing on electrical transformers?
Insulation Resistance
If the primary windings are a higher voltage and the secondary windings are a lower voltage, what type of transformer is this?
Step down transformer
What is the phase-to-phase (line-to-line) voltage of a commonly used split-phase transformer?
240 volts
What will happen if the frequency of a 50 Hz generator is changed to 60 Hz?
Nominal voltage increases by 20%
Which of the following tap conductor rules, as recommended by the NEC, commonly applies in commercial electrical services?
25-foot tap rule
Which one of the following transformer tests is very critical for connecting multiple transformers in parallel or in a bank?
Polarity test
What is the minimum gauge of copper ground ring required for a grounding electrode?
2 AWG
Which of the following may be the result of a faulty voltage regulator on a 3-phase generator?
All of the above
Which of the following materials is used to manufacture the core of an electric transformer?
Thin sheets of silicon and steel alloy
According to NEC standards, what is the maximum allowable percentage of overload protection on each phase of a motor marked with a temperature rise up to 104°F?
125% of full load current
Which of the following tests is NOT performed on an oil sample taken from a transformer?
Voltage drop
Which of the following positions is the correct connecting point for a neutral conductor in a Star (Wye) connection of a transformer?
Center of Wye connection
Which of the following arrangements is commonly used to step-up and step-down the voltage in a transformer?
Winding turn ratio
What is the minimum melting point of a sealing compound required for sealing the cable conduits used for electrical equipment installation in Class I/Division 1 locations?
200°F
What problem can occur if proper lubrication of a motor is not done on a recommended time interval?
Bearings will cease to move
According to NEC standards, which of the following surge protection arrangements is mandatory on commercial electrical installations in Class I/Division 1 locations?
All of the above
Which of the following statements is NOT true about the grounding of a transformer-driven alternating current system?
Any size of grounding electrode can be used
What is the recommended size of grounding copper conductor required for electrical equipment that is installed with a 600-ampere overcurrent protection?
1 AWG
Which heat removal mechanism is commonly used in large commercial transformers?
Oil cooling
According to the NEC, which of the following points can be used for the grounding of a transformer-driven alternating current system?
All of the above
How long do the motor starting capacitors normally operate in the motor-starting circuit to start a motor?
3 to 5 seconds
Which type of generator is commonly used for the generation of high power in commercial electrical systems?
Rotating field synchronous generators
Which of the following devices disconnects the starting windings on an induction motor when it reaches 80% of its speed?
Centrifugal switch
Which of the following can be the possible cause of a generator running at no load but with no AC output?
All of the above
In a 3-phase generator, which of the following feeds voltage to an auto voltage regulator (AVR)?
Auxiliary windings
Which of the following color codes is specified for a grounding conductor?
Green
If a generator is running on no load and AC output voltage remains between 60 V to 100 V, which of the following may be the cause of the problem?
Voltage regulator may be faulty
Which of the following is the main reason of development of overcurrent in electric motors?
All of the above
The measurement of continuous overload capacity at which a motor can operate without any damage to its life/performance is known as:
Service factor
Which of the following types of transformers is commonly used?
All of the above
If the load on a squirrel cage induction motor is reduced from the rated load, what will be the impact on the power factor?
Power factor decreases
What is the maximum allowable phase unbalance for the proper operation of electrical motors?
1%
What is the recommended conduit size for a luminary pole to junction box with a distance between about 5 ft. to 10 ft?
1”
Which of the following factors directly affect the speed of a synchronous motor?
Frequency
How many classes of hazardous locations have been identified by the NEC recommendations for commercial electrical equipment installation?
3 Classes
What is the impact on the lubrication interval of a motor that is installed vertically?
Lubrication interval halves
Which of the following is the industry's best practice for the installation of a conduit while crossing a roadway?
Installation of one extra conduit
Which of the following equipment is commonly used to check the health of diodes in the bridge connection installed on generators?
Ohmmeter
Which of the following pairs of insulation colors is NOT recommended by the NEC for phase (Hot) conductors?
White & Green
Which of the following protection systems is commonly used for controlling the voltage of a generator?
Automatic voltage regulator (AVR)
Which of the following motors is NOT a synchronous motor?
Squirrel cage motor
What is the maximum allowable voltage of any electrical part that can be left without insulation in dry conditions for Class I/Division 1 locations?
30 Volts
If a motor uses a cord and plug as a disconnect, what should the attachment plug be rated for?
Horsepower
How much electric power, in watts, will a 1-horsepower (HP) motor consume while operating at ideally 100% efficiency?
746 watts
Which of the following motors produces constant speed?
Synchronous motor
What is the maximum tolerable variation in power frequency that a commercial motor can withstand for proper motor operation?
5%
How many divisions of each class of hazardous location have been identified by NEC standards?
2 Divisions
Which of the following are two major types of alternating current motors extensively used in the industry?
Induction motor & Synchronous motor
What is the standard tolerable variation of voltage for 3-phase motors commonly used in the industry?
+/- 10%
Which of the following problems for 3-phase generators is the main reason for negative phase sequence in the generators?
Unbalanced phase currents
Which of the following types of motor requires an additional DC power source other than an alternating current source?
Synchronous motor
TOTAL QUESTIONS: 101 PASSING RATE: 80% PASSING SCORE: 81
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