Section 36 - High Voltage

Question 1

What are the five main hazards of High Voltage Installations?

Answer 1

1. Inadvertent contact
2. Step and touch potential
3. Back feed, mutual induction, and capacitive charge
4. Arc flash and arc blast
5. High voltage transients

Question 2

What colour are class 00 insulating rubber gloves?

Answer 2

Beige

Question 3

What is the voltage rating of green insulating rubber gloves?

Answer 3

26,500 V

Question 4

True or False:
Rubber gloves must always be covered with leather protectors

Answer 4

True. This is done to protect them from mechanical damage

Question 5

True or False:
Rubber insulating gloves must be tested by an authorized test facility every year

Answer 5

False. They must be tested every 6 months

Question 6

What are the different types of stranded conductors?

Answer 6

Concentric Round
Compact Round
Compact Sector
Annular
Segmental

Question 7

How many layers of strands does a concentric round conductor have?

Answer 7

4 layers wrapped around a single conductor

Question 8

What are the major components of a High-Voltage Cable?

Answer 8

Conductor
Strand Shield
Insulation
Insulating Shielding
Jacket

Question 9

What are some benefits of using rubber insulation?

Answer 9

Excellent resistance to moisture
Excellent dielectric strength
Low dielectric loss factor
Ozone Resistance

Question 10

Which insulation would I use for a high voltage installation that required high impact strength and maximum dielectric strength?

Answer 10

Thermoset Cross-Linked Polyethylene (XLPE)

Question 11

What are the advantages of Insulation Shielding?

Answer 11

1. Creates even radial distribution of voltage stress (electrostatic field). This even distribution prevents insulation breakdown and cable failure.
2. Limits Radio interference
3. Reduces induced potentials

Question 12

What are the two types of insulation shielding?

Answer 12

Metallic and Non-metallic

Question 13

What is Flashover?

Answer 13

An arcing caused by a high-voltage difference between the insulation shield and exposed conductor.

Question 14

An arcing caused by a high-voltage difference between the insulation shield and exposed conductor would be called what?

Answer 14

Flashover

Question 15

What is Dielectric Strength?

Answer 15

The highest voltage a dielectric can withstand before breakdown occurs. The breakdown point is reached when the dielectric material begins to conduct current.