High Voltage Questions Worksheet

Question 1

True or False. A 25kV, URD HV cable will have stand and insulation shielding in its construction

Answer 1

True

Question 2

True or False. For HV cables, the insulation thickness will increase with voltage increases

Answer 2

True

Question 3

True or False. Extra high voltage cables will have a thermoset insulation in the middle channel of the cable

Answer 3

False. Liquid or gas

Question 4

True or False. A common type of medium-voltage cable in general use today is Teck cable

Answer 4

True

Question 5

True or False. Dielectric strength of a material is the ability of the dielectric to withstand electrical breakdown under the influence of frequency

Answer 5

False. Voltage stress

Question 6

True or False. Dielectric strength will increase if a dielectric becomes heated

Answer 6

False. This weakens the insulation

Question 7

True or False. XLPE is a thermoset plastic

Answer 7

True

Question 8

True or False. IEEE classifies high voltage as 115,000 - 230,000V

Answer 8

True

Question 9

True or False. Some large electric motors operate at voltages as high as 13.8kV

Answer 9

True

Question 10

True or False. Most HV alternators generate electric power at voltages between 20kV and 40kV to reduce line losses

Answer 10

False. 10kV to 20kV

Question 11

True or False. The voltages used in the transmission system are generally 60kV - 765kV for BC Hydro

Answer 11

False. 500kV max

Question 12

True or False. PVC is a thermoplastic material

Answer 12

True

Question 13

True or False. The conductor shield overcomes the problem of ionized air between the conductor strands

Answer 13

True

Question 14

True or False. The insulation shield creates an equidistant radial flux in the insulation

Answer 14

True

Question 15

True or False. If the insulation shield was constructed of lead it would also prevent the ingress of moisture into the cable

Answer 15

True

Question 16

True or False. The grounded shield acts to protect life in the event of mechanical damage to the cable

Answer 16

True

Question 17

True or False. 100% insulation is used in grounded systems, where ground faults are eliminated in no more than one hour

Answer 17

False. 133%

Question 18

True or False. Cable armour provides HV cable with mechanical protection

Answer 18

True

Question 19

True or False. A pothead is a termination method that has been traditionally used on shielded Teck power cables

Answer 19

False. PILC cables

Question 20

True or False. Its better to have a creep age distance a little too long, as opposed to too short when terminating HV cable

Answer 20

True

Question 21

True or False. Moisture and contaminants on the insulation could cause current tracking and flashover

Answer 21

True

Question 22

True or False. Splicing a HV cable is considered more difficult than terminating a HV cable

Answer 22

True

Question 23

True or False. A common reason for a HV splice to fail is air getting trapped in between layers of insulation

Answer 23

True

Question 24

What is the process called when air breaks down and becomes a conductor?

Answer 24

Ionization

Question 25

What represents a power loss in lines and can cause radio and TV interference?

Answer 25

Corona

Question 26

What is is called when current tries to flow across insulation to ground?

Answer 26

Tracking

Question 27

What is used on HV insulators and cable terminations to increase the creepage distance?

Answer 27

Skirting

Question 28

The ability to withstand a very high voltage for short duration is called ________

Answer 28

Impulse voltages

Question 29

What is created on the insulation surrounding a conductor due to an electrostatic field?

Answer 29

Electric stress

Question 30

Created because the flux concentrations are decreasing with distance which means the stress on the insulation decreases with distance

Answer 30

Voltage gradient

Question 31

The result of dust collecting on HV insulators or terminations

Answer 31

Flashover

Question 32

Relates to the minimum separation required between energized HV conductors

Answer 32

Strike Distance

Question 33

True or False. An electrostatic field is due to conductive air

Answer 33

False. Voltage

Question 34

True or False. A radial system is an expensive form of HV supply for rural locations

Answer 34

False. It is the cheapest

Question 35

True or False. A ring system is also called a loop system

Answer 35

True

Question 36

True or False. A network system is essentially a loop system with additional interconnecting ties

Answer 36

True

Question 37

True or False. The network system is used for supplying HV power to major airports

Answer 37

True

Question 38

True or False. Lightning arresters are connected in parallel to the load

Answer 38

True

Question 39

True or False. Reactors are connected in series to the load

Answer 39

True

Question 40

True or False. Unit substations are common used for the supply of large industrial and commercial installations

Answer 40

True

Question 41

True or False. A substation that contains HV equipment is usually located outdoors and includes disconnects, circuit breakers, power transformers, lightning arresters, etc

Answer 41

True

Question 42

True or False. A radial system used for the supply of power for rural locations is the easiest to protect against overload and short-circuits

Answer 42

True

Question 43

True or False. The loop system offers a higher degree of reliability than the radial system

Answer 43

True

Question 44

True or False. A HV vault must be built of concrete and located so that at least one wall is an outside wall

Answer 44

True