High Voltage Self Test 1

Question 1

According to the CEC, HV is any voltage above?

Answer 1

1000V

Question 2

What is medium voltage defined by the IEEE standards?

Answer 2

2.4KV-69KV

Question 3

An electrostatic field is due to which of the following? Voltage, Current, Air, Resistance

Answer 3

Voltage

Question 4

What effect does electric stress have on insulation?

Answer 4

Weakens the insulation

Question 5

Why is creepage distance kept relatively long?

Answer 5

To minimize leakage current over insulation

Question 6

What does BIL stand for, and what significance does it have for the insulation of HV equipment?

Answer 6

Basic impulse insulation level, Requires higher level of insulation then rated voltages would indicate

Question 7

What are the 3 broad classes of HV distribution systems?

Answer 7

Radial, Ring/loop, Network

Question 8

Which distro system is the least expensive and the simplest?

Answer 8

Radial

Question 9

Name the distro systems in terms of their levels of reliability

Answer 9

Network(most reliable), Ring/loop, Radial(least reliable)

Question 10

What distro system requires the most comprehensive protection system?

Answer 10

Network

Question 11

A rural overhead distro line is most likely to be a?

Answer 11

Radial distro system

Question 12

What is a substation?

Answer 12

area outisde that contains CB’s, disconnects, lightning arrestors and Transformers

Question 13

What is a unit substation?

Answer 13

modular constructed enclosure house the HV cable terminations, bus bars, CB’s, transformers, low voltage CB’s, instrument transformers

Question 14

Purpose of viewing windows in unit substations?

Answer 14

visible indication of a switch being open or closed

Question 15

HV equipment must always be installed in a vault? T/F

Answer 15

False

Question 16

What is the primary purpose of a series reactor in an HV system?

Answer 16

to limit the magnitude of fault current or limits current spike

Question 17

How can the use of series reactors reduce the cost of subsation installations?

Answer 17

by allowing the uage of CB’s with lower ampacity ratings

Question 18

What is the function of a surge arrestor?

Answer 18

to protect against over voltages

Question 19

What are the main parts of a surge arrestor?

Answer 19

Air gap and thyrite material

Question 20

2 Functions of intrument transformers in an HV system?

Answer 20

-to monitor voltage and current levels
-to isolate monitoring devices from HV systems

Question 21

What is the most common secondary voltage of a VT?

Answer 21

120V

Question 22

What is the most common secondary current rating of a CT?

Answer 22

5A

Question 23

What is the purpose of key interlocking?

Answer 23

safety measure to prevent accidents/incidents and protect equipment

Question 24

What are the 5 general steps to be taken in a safe switching sequence?

Answer 24

1) disconnect 2)lockout 3)test 4)ground and short circuit 5) screen off nearby live parts

Question 25

the minimum safe distance to be maintained when work is to be done in the vicinity of a 25kv line is?

Answer 25

10 feet

Question 26

Which is more likely to be higher? Step or touch voltage

Answer 26

Touch Voltage

Question 27

Is a ground mat made of insulating or conducting material?

Answer 27

Conducting Material