PHEP_31B

Question 1

Most transmission lines are arranged to:
a) provide low voltage and high current
b) provide an alternate route of power in case of a fault
c) provide means to canel all the capacitance in a line
d) provide means to cancel all inductance in a line

Answer 1

b) provide an alternate route of power in case of a fault ref: p. 3

Question 2

I2R losses during transmission of electrical power are:
a) affected by both load and load factor
b) affected by inductance only
c) affected by the power factor and inductance only
d) by the pure resistance and capacitance only

Answer 2

a) affected by both load and load factor ref: question 5

Question 3

Two of the general categories of transmission line disturbance are arching grounds and lightning. What is the third?
a) control outputs for converters
b) bundle conductor
c) low voltage
d) switching

Answer 3

d) switching ref: p. 27

Question 4

The energy stored in the magnetic fields of conductors is called:
a) always lost to the system
b) called I2R losses
c) given back to the system with an increase in current or voltage
d) called watt-less energy

Answer 4

d) called watt-less energy ref: p. 11

Question 5

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

Answer 5

c) carry an appreciable amount of the load current ref: p. 15

Question 6

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

Answer 6

d) all three ref: p. 21

Question 7

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

Answer 7

a) increasing voltage value ref: p. 24

Question 8

Bundled conductors:

a) increasing flux density
b) reduce inductive reactance
c) encourage the formation of corona
d) decrease the clearance requirements at the tower

Answer 8

b) reduce inductive reactance ref: p. 25

Question 9

Overhead ground wires will usually protect either side of the vertical of the transmission line conductors from lightning about:

a) 90 degrees
b) 60 degrees
c) 45 degrees
d) 30 degrees

Answer 9

d) 30 degrees ref: p. 22

Question 10

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

Answer 10

b) done on the low-voltage side ref: p. 27

Question 11

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

Answer 11

d) all three ref: p. 30

Question 12

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

Answer 12

c) a valve-type lightening arrestor ref: p. 36-37

Question 13

All of the below are considered as advantages in the transmission of HVDC as compared to AC, except for:

a) its non-synchronous characteristic permits interconnection to AC systems of different frequencies
b) the earth may be used as one conductor in emergencies
c) the overall insulation requirements may be based on the peak rather the actual voltages
d) fault current may be limited to much lower percentages of rated current

Answer 13

c) the overall insulation requirements may be based on the peak rather the actual voltages ref: p. 42

Question 14

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

Answer 14

c) cannot be protected from faults by using conventional circuit breakers ref: p. 43

Question 15

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

Answer 15

a) the quantity and direction of power flow may be controlled with high accuracy and extreme rapidity ref: p. 55