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WorksheetsNLC Final Egrid 2
Total questions: 53
Worksheet time: 27mins
Which of the following statements about parallel circuits is true?
The current in a parrallel circuit stays the same, while the voltage changes at different points in the circuit
The voltage in a parallel circuit stays the same, while the current changes at different point in the circuit
The resistance in a parallel circuit stays the same, while the voltage changes at different points in the circuits
The current in a parallel circuit stays the same, while the reistance changes at different points in the circuits
Which is true about a delta system?
System voltage is higher than coil voltage
Coil voltage in the same as system voltage
Coil voltage is higher than system voltage
System voltage is lower than coil voltage
Which of the following statements about systems is true?
Single-phase tap lines on delta systems consist of two phases
In the field, four-wire wye systems and delta systems are identical in appearance
The neutral is extended throughout the circuit
Today, wye systems exist only in insolated
If the applied voltage is 12,000 volts, what is the current draw for the 15 KVA transformer?
2 amps
1.25 amps
2.08 amps
3.47 amps
In the above graphic, the current is 6.6 amps and each streetlight is 200 watts. How much voltage does the transformer have to supply to push 6.6 amps through each streetlight?
242.4 volts
1320 volts
792 volts
403.03 volts
If the voltage is 120 volts and each light bulb is 15 ohms, what is the current?
8 amps
16 amps
15 amps
4 amps
If the applied voltage is 19,900 volts, what is the current draw at the line switch?
3.47 amps
1.25 amps
2 amps
.75 amps
If the voltage is 120 volts and bulb #2 is 80 watts, what is the current at bulb #2?
1.16 amps
.66
.5
1.5 amps
Refer to the above graphic and choose the closest possible answer to phase current.
24
83
28
48
Refer to the above graphic and choose the closest possible answer to coil current.
23
26
33
45
If the current is 5 amps and each light bulb is 6 ohms, what is the current draw across each bulb?
24 amps
36 amps
12 amps
5 amps
If the applied voltage is 14,400 volts, what is the current draw at the line switch?
1.04 amps
2.78 amps
1.74 amps
5.55 amps
Each coil of wire on a three-phase generator will produce _____
Its own voltage and current
A wye voltage and current
Three instances of voltage and current
A delta voltage and current
Refer to the above graphic and choose the closest possible answer to coil current.
18
15
52
30
What does this image represent?
A weakened point
A series circuit
An open circuit
A short circuit
Choose the letter of the graphic that indicates that the phases are in sequence.
A
B
C
D
What is this item used for?
Testing a phasing meter
Charging a phasing meter
Testing grounds
Cheking rotation
Choose the letter of the graphic that shows a change in rotation.
A
B
C
D
Which statement best describes what is occurring in this graphic?
Both sides of the opening point are energized at system voltage
The reading on the meter indicates proper phase sequence
The phase sequence was accidently changed
Voltage is not present on one side of the normal open
Which of these statements about the advantages of three-phase systems is true?
Motors are smaller and less expensive than single-phase equipment of the same rating
There is an increase in conductors and a decrease in power capability
The generators are larger and more expensive than single- phase generator of the same rating
More pulsating force is applied to rotating generations and motors
How can you tell if a system is a three-wire wye or a delta configuration in the field?
Take a phase-to-phase voltage measurement
Visually inspect the number of wires on the pole
Measure the phases on a single-phase tap line using an ammeter
Confirm the secondary connections of the substation transformer bank
Which is true about a wye system?
Coil current is higher than phase current
Phase current is lower than coil current
Phase currentis higher than coil current
Coil current is the same as phase current
What is the difference between generating single-phase and three-phase power?
Single-phase generators have one magnet and three-phase generators have three magnets
Single-phase power uses one generator and three-phase power uses three generator
Single-phase power is delta and three-phase power is wye
Single-phase generators have one wire coil and three-phase generators have three wire coils
Which of these statements explains why three-phase results in smoother and more efficient operation of equipment?
Because no power is produced when the cycle is at zero on the sine wave
When one phase is at zero, the other two provide power to the circuit
The motor relies on inertia to keep it spinning, which uses less power
The load is larger than a single-phase load providing the same output
In a three-phase system, when one phase is at zero on a sine wave, what are the other two phases doing?
They are proving power to the circuit
They cancel out fluctuation on the circuit
They are also at zero on the sine graph
The provide peak power to the circuit
Which of these statements about the advantages of three-phase systems is true?
Motors are smaller and less expensive than single-phase equipment of the same rating
There is an increase in conductors and a decrease is power capability
More pulsating force is applied to rotating generations and motors
The generators are larger and more expensive than single-phase generators of the same rating
The direction that each individual three-phase motor needs to rotate is determined by:
Lineworkers using a high-voltage phasing meter
Electricians using customer equipment specifications
Lineworkers using a rotation meter
Electricians using the angle of rotation of the generator
What can sometimes be used on a three-phase main feeder before and after the work is completed, but before the jumpers are closed, to verify that the jumper connections are correct?
A set of phasing sticks
A neutral position indicator for overhead services
Fault indicators for underground services
A multimeter across the normal-open switch
What does it mean if the phasing meter displays system voltage across the open contacts on "A" phase of a switch?
Clase the switch-the phasing sequence is correct
Do not close the switch- the phasing sequence is not correct
Rocky vs drago
Fight in the parking
Which of the following best describes why a shaft would unscrew from a well pump?
Excessive rotation speed
The generator lagged in rotation
A change in rotation
The three-phase motor was faulty
when the _______ is maintained throughout the system, three- phase motors will spin in the same direction as the generator
Angle of rotation
Phase angle
Generation voltage
Phase sequence
Which of these statements about the advantages of three-phase systems is true?
More pulsating force is applied to rotating generations and motors
There is an increase in conductors and a decrease in power capability
Motors are smaller and less expensive than single-phase equipment of the same rating
The generators are larger and more expensive than single-phase generators of the same rating
Each coil of wire on a three-phase generator will produced _________
A delta voltage and current
Its own voltage and current
Three instances of voltage amd current
A wye voltage and current
What is the main difference between a wye and delta configuration on a three-phase generator?
The direction of rotation
The connection between the coils
The shape of the generator housing
The shape of the magnet
One bulb burns out, and the rest go out as well. This is an example of a
Series circuit
Short circuit
Parellel circuit
Fusible element
Series circuits are circuits that have only one path for______
Voltage drop
Resistance
Power
Current flow
Power lines are considered to be what kind of circuit?
Combination type circuit
Predominantly series
Series circuits
Short circuits
Which of the following statements about parallel circuits is true?
The resistance in a parallel circuit stays the same, while the voltage changes at different points in the circuits
The current in a parallel circuit stays the same, while the voltage changes at different point in the circuit
The current in a parallel circuit stays the same, while the resistance changes at different point in the circuit
The voltage in a parallel circuit stays the same, while the current changes at different points in the circuit
If the phase sequence is unchanged, motor rotation will _____
Rotate anticlockwise
Rotate clockwise
Change
Remain unchanged
Short circuits have very low:
Amperage
Resistence
Wattage
Voltage
If too much current flows, the capacity of the _____ will be exceeded
Conductor
Series circuit
Source
Parallel circuit
What can be said about current in a series circuit?
The applied current it available to each leg of the circuit
Each resistor only draws its own current
It is the same at any point in the circuit
It is all used up after the last load in the circuit
Which of the following best describes what lineworkers can do to maintain correct rotation before doing any work that requires disconnecting jumpers or conductors on the primary portion of the pole?
Use a rotation meter to check voltage
Memorize the jumper configuration on a corner pole
Draw a jumper schematic on the job print
Use a phasing meter across open points to verify phases
Study each graphic carefully. Choose the letter of the graphic that shows a future cross-phase situation at the normal open.
A
B
C
D
Why do utilities find wye systems more efficient than delta systems?
Wye systems are cheaper to install because they use fewer resources
Wye systems produce more power from the same generator
Wye systems can serve a give load with less voltage than delta systems
Wye systems can serve a give load with less current than delta systems
To prevent phasing errors, some line crews_______ before work begins
Paint jumper connections on the street near the corner pole
Perfom a cross-phase check using a phase meter
Use a voltage meter to check continuity
Use a rotation meter to check voltage
How can you tell if a system is a three-wire wye or a delta configuration in the field?
Confirm the secondary connections of the substation transformer bank
Take a phase to phase voltage measurement
Visually inspect the number of wires on the pole
Measure the phases on a single- phase tap line using an ammeter
What is step one of the sequence for proving phasing?
After a zero reading, perfom a cross-phase check
Use the manufacturer testing socket to verify the meter is working properly
Confirm proper phase sequence between the open points using the phase meter
Verify the correct voltage on both sides of the open point
Study the above graphical representation of circuits. Choose the one that best represents power line circuits.
A
B
C
D
Which statement is true about parallel circuits?
The applied current in the same at each leg of the circuit
If one bulb burns out, the others mill not be affected
All of the current is used up after the last load
Current only has one path to flow
When working on a system voltage of 14.4/24.9 KV, select the proper rubber cover-up equipment that must be used.
Type ll
Class 1
Class 3
Type 2
When an energized rod is placed inside a rubber glove filled with water, what is happening?
Recycling
Inspection
Insulation rebuilding
Electrical testing
What is the point at which current leaves the body during simultaneous contact between two or more items of different potential?
Clearance point
Primary point of contact
Second point of contact
Achor point
