PHEP #31 Flashcards
Transmission lines are used for the purpose of:
a) transmitting the highest voltage circuits on a given strength
b) tying together the major generating stations and primary substations
c) interconnecting major electrical systems for the interchange of power
d) all three
d) all three
In discussing related characteristics of transmission lines, it can be said that the higher the voltage the…
a) larger the conductor size
b) lower the I^2R losses
c) the higher voltage drop
d) all three
b) lower the I^2R losses
Electrostatic and electromagnetic unbalance between phases in a 3 phase transmission line is reduced by:
a) transposing or rotating the conductors
b) decreasing the space between conductors
c) the delta arrangements
d) lowering the charging current
a) transposing or rotating the conductors
The energy stored in the magnetic fields of conductors is called:
a) always lost to the system
b) called I^2R losses
c) given back to the system with an increase in current or voltage
d) called watt-less energy
d) called watt-less energy
The steel core of ACSR conductors does not:
a) add to the strength of the conductor
b) require corrosion protection
c) carry an appreciable amount of the load current
d) require stranding of the steel wire
c) carry an appreciable amount of the load current
Suspension type insulators:
a) must be able to accept flashover without shattering
b) are designed to resist thermal shock
c) should be able to accept some amount of mechanical impact
d) all three
d) all three
Transmission line losses due to corona may be reduced by all of the below except:
a) increasing voltage value
b) increasing the diameter of the conductor
c) keeping the surface of the conductor as clean and smooth as possible
d) increasing the spacing between conductors
a) increasing voltage value
Bundled conductors:
a) increasing flux density
b) reduce inductive reactance
c) encourage the formation of corona
d) decrease the clearance requirements at the tower
b) reduce inductive reactance
An electrical transmission system may be caused to drop out of step or become unstable by:
a) a sudden increase in load
b) a sudden decrease in load
c) a short-circuit
d) all three
d) all three
Switching performed under short-circuit conditions is apt to be the most disturbing to transmission lines when
a) done on the high voltage side
b) done on the low-voltage side
c) done under no-load conditions
d) all three
b) done on the low-voltage side
The voltages induced in the lead sheath of underground cables may be eliminated by:
a) installing porcelain insulators to sectionalize the sheath
b) transposing
c) cross-bonding
d) all three
d) all three
A material, such as Thyrite, would most likely be used in:
a) an explosion-type lightening arrestor
b) a pallet-type arrestor
c) a valve-type lightening arrestor
d) none above
c) a valve-type lightening arrestor
All of the below are considered as advantages in the transmission of HDVC as compared to AC, except for:
a) other
b) other
c) the overall insulation requirements may be based on the peak rather the actual voltages
d) other
c) the overall insulation requirements may be based on the peak rather the actual voltages
HVDC transmission lines:
a) are always subject to the effects of inductive capacitance
b) can never use more than two conductors
c) cannot be protected from faults by using conventional circuit breakers
d) require no overhead wires for lightening protection
c) cannot be protected from faults by using conventional circuit breakers
In a HVDC transmission system:
a) the quantity and direction of power flow may be controlled with high accuracy and extreme rapidity
b) the amount of power transmitted is determined by the difference of phase angle between networks
c) the amount of power transmitted is determined by the line characteristics
d) power flow affected by load characteristics
a) the quantity and direction of power flow may be controlled with high accuracy and extreme rapidity
