High Voltage Self Test 3

Question 1

HV switches are rated for which three primary electrical quantities?

Answer 1

Voltage, Current, Frequency

Question 2

What type of switch might be operated using a hot stick?

Answer 2

Isolating swtich

Question 3

Where is a horngap switch normally located?

Answer 3

Pole top

Question 4

What level of HV system normally uses load-break switches?

Answer 4

Medium Voltage

Question 5

Which feature in a disconnet switch provides information about its open status?

Answer 5

Visible separation between contacts

Question 6

What advantage does a load break switch have over a CB?

Answer 6

low cost

Question 7

One differnce between a metal clad switch and a metal enclosed switch?

Answer 7

Metal clad has the drawer feature and the metal enclosed doesn’t

Question 8

Hotstick normally made of what material?

Answer 8

Fibreglass

Question 9

Main physical difference between a HV fuse and a LV fuse?

Answer 9

HV fuse is longer

Question 10

Fuses are likely to be found in trasmission systems than in distro systems? T/F

Answer 10

False

Question 11

Difference between a fuses current rating and interrupting current rating?

Answer 11

Current rating is the magnitude of current it can carry continuously without blowing, interrupting current rating is the magnitude of current it can safely interrupt

Question 12

Primary reason to use a current limiting fuse?

Answer 12

To limit current to reduce stress/damage to equipment

Question 13

What type of fuse has replaceable cartridge?

Answer 13

Solid materials fuse

Question 14

What type of fuse has replaceable fuse link?

Answer 14

Distribution cutout

Question 15

What type of fuse does not use some form of spring action to assist opening?

Answer 15

Current limiting

Question 16

What is necessary for using a solid materials fuse indoors?

Answer 16

Condensor is necessary for collecting expelled materials

Question 17

What is the de-ionizing agent used in a solid materials fuse?

Answer 17

Boric acid powder

Question 18

Which type of HV fuse is to be encountered nowadays?

Answer 18

Liquid type

Question 19

What two useful fucntions are provided by the distribution cutout fuse in dropping down when the fuse holder opens?

Answer 19

visibile indication that the fuse is opened, and theres no chance of restrike

Question 20

The distribution cutout must be replaced using a?

Answer 20

Hotstick

Question 21

List 5 types of CB’s

Answer 21

-Air magnetic
-Air blast
-Vacuum
-Oil
SF6

Question 22

Wha tprovides the force that moves the contacts in most CB’s?

Answer 22

Springs

Question 23

What important characteristics does a CB have compared to a load break switch?

Answer 23

CB has the ability to interrupt high fault current

Question 24

List in sequence the four steps to take for locking out before working on HV equipment?

Answer 24

Disconnect, Lockout and Tag, Prove absence of voltage, Ground

Question 25

What must be done before using an approved tester to test for absence of voltages?

Answer 25

verify the tester itself is working

Question 26

What is the first connection to be made when using ground leads to ground de-energized phase conductors?

Answer 26

ground leads must be connected to ground before they are connectted to the phase conductors

Question 27

How is access to adjacent live equipment prevented ?

Answer 27

Through the use of barries and warning signs

Question 28

According to CEC regulations, what safety feature must compartments containing HV fuses have?

Answer 28

interlocking

Question 29

When used indoors, HV fuses must be in an acceptable enclosure or in a room of what type of construction?

Answer 29

non combustible

Question 30

List three pieces of HV equipment that frequently use HV fuses?

Answer 30

Transformers, capacitors, motors

Question 31

Spacing between fuses must increase with what?

Answer 31

Voltage rating

Question 32

When used for the protection of VT's, the current raitng of a fuse must not exceed?

Answer 32

3A

Question 33

With what type of switch are current-limiting fuses commonly used?

Answer 33

Load break

Question 34

What is the purpose of fuse interlocking?

Answer 34

to prevent someone from entering a fused cubicle compartment that is live

Question 35

Is there a difference between the sapcing requirements of expulsion and non expulsion fuses?

Answer 35

Yes any voltages there is more space required for expulsion then non-expulsion

Question 36

What is the purpose of a protective relay?

Answer 36

to monitor circuit or equipment conditions and to initate an alarm trip if the conditions warrant it

Question 37

Most common HV relay?

Answer 37

inverse time overcurrent relay

Question 38

4 common qualities monitored by protective relays?

Answer 38

-Current -Voltage -Power -Frequency

Question 39

What is the most common method of achieving time delay in an electromechanical relay?

Answer 39

using a shaded pole/induction disk relay

Question 40

List three non electrical quantities that frequently need monitoring in electrical HV systems?

Answer 40

Temperature, Pressure, Vibration

Question 41

What type of relay is becoming more common in protective systems?

Answer 41

Solid state relay

Question 42

What is meant by the term inverse time with respect to the overcurrent relay?

Answer 42

triop time decreases as current increases

Question 43

What causes the aluminum disk to turn and tend to close the contacts in the induction type overcurrent relay? What causes the restraining torque?

Answer 43

Current flow in the coil of the relay coming from the associated CT, A spring causes the restraing torque.

Question 44

The time taken for timed contacts to clsoe depends on?

Answer 44

CT current, Travel distance of the disc, relay coil turns

Question 45

What is the purpose of using differential protection?

Answer 45

to protect agaisnt groundfaults and interphase faults

Question 46

Identify some positive features of solid state relays?

Answer 46

Compactness, accuracy, memory, reliability

Question 47

What devices do the ANSI designations 50,51, and 52 identify?

Answer 47

-50 instantaneous over current realy -51 time trip overcurrent relay -52 AC CB

Question 48

Protective relay settings can be altered without removing them from the panel. T/F

Answer 48

True

Question 49

What is selective coordination with reference to relay settings?

Answer 49

the ability to remove only the section of the system where the fault has occured

Question 50

Switches on an overcurrent relay must be opened before the relay can be removed from its enclosure. The red-handed switch indicates which part of the circuit is being opened?

Answer 50

trip circuit

Question 51

What precuation must always be observed before opening the secondary of a CT?

Answer 51

The CT must be short circuited