NLC ELECTRICAL GRID 2 CH. 2 EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026
Advantages of a three phase system over single phase: - Answers -a 73% increase in power capability
for a 50% increase conductor
-less pulsating force applied to rotating generators and motors
-Generators, transformers, and motors are smaller and less expensive than single phase equipment of
the same rating
What are the differance in power generation of 3 phase compared to single phase? - Answers single
phase has one coil of wire, where 3 phase has 3
what is the spacing of the 3 phase coils? - Answers equally spaced 120 degrees
What does each coil on a 3 phase generator do? - Answers produces its own current and voltage,
making a three phase sine wave
how many times does a single phase cycle hit zero? - Answers 3 times
Because a single phase motor receives no power 3 times per cycle what must it rely on? - Answers its
own inertia to keep it spinning during those times
on a three phase motor, when one phase is at zero the other two are? - Answers providing power to
the circuit
What are the two coil configurations a three phase generator can be connected in? - Answers Delta or
WYE
What is the formula for coil voltage in a WYE System? - Answers Coil Voltage = System Voltage/ 1.732
What is the formula for system voltage in a WYE System? - Answers system voltage= coil voltage x
1.732
What is coil voltage in a WYE? - Answers Phase to neutral reading
What is system voltage in a WYE? - Answers phase to phase
In a WYE system coil current is equal to? - Answers phase current
In a WYE system phase current is equal to? - Answers coil current
In a Delta system the system voltage is the same as? - Answers coil voltage
What is the formula for coil current? - Answers coil current= phase current/1.732
What is the formula for phase current? - Answers phase current= coil current x 1.732
Wye systems can serve a given load with less _______________ than a delta system; thus increasing
the efficiency of the system. - Answers current
What is the prodominent system used today? - Answers wye
In the early days of linework which system was believed to be safer for a linemen to work on
energized? - Answers delta
Could a lineworker work on a energized delta line barehanded from the pole on a delta system? -
Answers yes
due to the fact that a delta system has no nuetral, when would it be possible for this system to have a
short circuit? - Answers the only means of a short circuit is between the phases
Back in the day what were the common hazards that could cause a short curcuit on a delta line? -
Answers tree limb rubbing one of the other phases, another lineman working on a different phase of
the same circuit, broken insulators, faulty arrestors, etc/
What was the term used to describe a problem when working phases barehanded? - Answers cross
phase potential
What started to fade away as rubber gloves and live line tools and procedures improved? - Answers
delta systems
3 wire Wye? - Answers wye systems without a nuetral
Are three wire wye systems and delta systems identical in the feild? - Answers yes, the only way to
determine the true identity of the system is to confirm the secondary connections of the substation
transformer bank
Which system is most widely used? - Answers 4 wire wye
Why is the four wire wye much more reliable? - Answers it protects against fault current providing an
immediate and reliable path to the substation.
When does protective equipment start to operate on a three wire wye? - Answers in the case if one
phase fell to the ground, current must return to the source through the earth before equipment can
operate.
Advantages of a three phase system over single phase: - Answers -a 73% increase in power capability
for a 50% increase conductor
-less pulsating force applied to rotating generators and motors
-Generators, transformers, and motors are smaller and less expensive than single phase equipment of
the same rating
What are the differance in power generation of 3 phase compared to single phase? - Answers single
phase has one coil of wire, where 3 phase has 3
what is the spacing of the 3 phase coils? - Answers equally spaced 120 degrees
What does each coil on a 3 phase generator do? - Answers produces its own current and voltage,
making a three phase sine wave
how many times does a single phase cycle hit zero? - Answers 3 times
Because a single phase motor receives no power 3 times per cycle what must it rely on? - Answers its
own inertia to keep it spinning during those times
on a three phase motor, when one phase is at zero the other two are? - Answers providing power to
the circuit
What are the two coil configurations a three phase generator can be connected in? - Answers Delta or
WYE
What is the formula for coil voltage in a WYE System? - Answers Coil Voltage = System Voltage/ 1.732
What is the formula for system voltage in a WYE System? - Answers system voltage= coil voltage x
1.732
What is coil voltage in a WYE? - Answers Phase to neutral reading
What is system voltage in a WYE? - Answers phase to phase
In a WYE system coil current is equal to? - Answers phase current
In a WYE system phase current is equal to? - Answers coil current
In a Delta system the system voltage is the same as? - Answers coil voltage
What is the formula for coil current? - Answers coil current= phase current/1.732
What is the formula for phase current? - Answers phase current= coil current x 1.732
Wye systems can serve a given load with less _______________ than a delta system; thus increasing
the efficiency of the system. - Answers current
What is the prodominent system used today? - Answers wye
In the early days of linework which system was believed to be safer for a linemen to work on
energized? - Answers delta
Could a lineworker work on a energized delta line barehanded from the pole on a delta system? -
Answers yes
due to the fact that a delta system has no nuetral, when would it be possible for this system to have a
short circuit? - Answers the only means of a short circuit is between the phases
Back in the day what were the common hazards that could cause a short curcuit on a delta line? -
Answers tree limb rubbing one of the other phases, another lineman working on a different phase of
the same circuit, broken insulators, faulty arrestors, etc/
What was the term used to describe a problem when working phases barehanded? - Answers cross
phase potential
What started to fade away as rubber gloves and live line tools and procedures improved? - Answers
delta systems
3 wire Wye? - Answers wye systems without a nuetral
Are three wire wye systems and delta systems identical in the feild? - Answers yes, the only way to
determine the true identity of the system is to confirm the secondary connections of the substation
transformer bank
Which system is most widely used? - Answers 4 wire wye
Why is the four wire wye much more reliable? - Answers it protects against fault current providing an
immediate and reliable path to the substation.
When does protective equipment start to operate on a three wire wye? - Answers in the case if one
phase fell to the ground, current must return to the source through the earth before equipment can
operate.
