Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Midterms > EE Elective Q2 > Flashcards

EE Elective Q2 Flashcards

(67 cards)

Start Studying
1
Q

In the British standard, S1 refers to

A

Strike directly to the structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

A lightning flash is a constant source of

A

current

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The most common source of lightning cloud form is

A

cumulonimbus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The National Electrical Code recommends additional electrode if a resistance to ground greater than

A

25 ohms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The typical duration of a lightning flash approximately

A

0.5 sec

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Improving earth resistance includes

A

Treat the soil,
Use multiple rods, and
Lengthen the earth electrode in the earth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

This method of measuring earth resistance is best applied when a simple ground system with existing return path through multiple grounds is present

A

clamp-on

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Methods of designing the air termination network includes

A

The rolling sphere,
The protective angle design, and
The mesh design

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Types of LPS earthing systems includes except
a) Type A
b) Type B
c) Type C
d) Foundation earth electrode

A

c) Type C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Key design elements for static dissipators based on point discharge theory includes

A

Radius dissipator electrode,
Number of dissipator electrode, and
Dissipator construction material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The positive leader ground-to-cloud discharge

A

Category 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Refers to location where at risk of full lightning strike and the full lightning electromagnetic field

A

LPZ 0a

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The minimum recommended thickness of stainless steel sheet considered as part of LPS is

A

0.50 mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The cone of protection is determined by

A

Both height of structure and storm cloud

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The lightning protection system is required to

A

Conduct the lightning strike safely to ground,
Disperse the strike safely in the earth, and
Intercept the lightning strike

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Basic test methods for earth resistance measurements

A

Clamp-on test method,
Dead earth method, and
Fall-of-Potential method

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Factors affecting earth resistivity includes except
a) Type of soil
b) Method of measurement
c) Moisture content
d) Temperature

A

b) Method of measurement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

The average peak current for the first impulse lightning is

A

18kA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

The average peak current for the first impulse lightning is

A

18kA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

British design of lightning protection system is based on

A

Rolling sphere method
Protective angele or cone method
Use of natural conductors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Most common form of lightning that account for 90% or more of the cloud-to-ground flashes worldwide is

A

Category 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Lightning effect can be compared to

A

capacitor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Are typically three or four high current pulses in a single flash made up of various discharge components

A

Strokes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

A device used on power systems above 1000V to protect other equipment from lightning and switching surges

A

Lightning Arrester

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Devices that divert lightning surges to ground
Lightning Rods
25
Other devices similar to Lightning Arresters also surge diverter, but generally for voltages well below 1000 volts
Surge Suppressor TVSS (Transient Voltage Surge Suppressor)
26
The heart of all arresters
MOV (Metal Oxide Varistor)
27
A semiconductor that is sensitive to voltage. It is very fast acting electronic switch.
MOV Disk
28
Meaning of CSST
Corrugated Stainless Steel Tubing
29
Design of LPS refers to the location where the protected zone inside the building
LPZ 1
30
Design of the LPS refers to the location where not at risk from a direct lightning strike considering the protected area through the rolling sphere but at risk from the full lightning electromagnetic impulse
LPZ 0b
31
Design of LPS that refers to the location where protected zone with further dampened magnetic field
LPZ 2
32
This method simply rolls a sphere around the building to be protected.
The rolling sphere
33
Only used in simple structures or for small sections of larger structures.
The protective angle design
34
Most commonly used method in designing the air termination network, is usually employed where the structure is simple, a square or rectangular building or typical house
The mesh design
35
A neutral conductor is usually colored
white
36
A system which is not solidly earthed but is connected to earth through a current limiting impedance
IT System
37
The permanent joining of metallic parts to form an electrically conductive path that ensures electric continuity and the capability to conduct safely any current likely to be imposed
Bonded
38
An installation where an earth terminal is not provided by the electric supply company
TT system
39
Electric shock severity is determined by the following except a) amount of current through body b) path of current through body c) length of time current flows d) ambient temperature
d) ambient temperature
40
Is an iron core reactor connected between transformer neutral and ground. It is used for limiting the capacitance earth fault current which is flowing when the line ground fault occurs in the line.
Peterson coil
41
The path followed by the fault current as the result of low impedance occuring between the phase conductor and earthed metal
earth fault loop
42
It is called earthing well
inspection point
43
Color of neutral conductor
Gray
44
The vast majority of of surge suppressors today use
Metal Oxide Varistor
45
A device that establishes an electrical connection to the earth
Grounding electrode
46
Insulation breakdown occurs because of the following except a) Mechanical b) Electrical c) Chemical d) Thermal
b) Electrical
47
Transient over voltage is normally classified as one of the following types except a) Slow front b) Medium front c) Fast front d) Very fast
b) Medium front
48
Color of equipment grounding conductor
Green
49
The selection of the insulation strength of equipment in relation to the voltages which can appear on the system
Insulation coordination
50
This is probably the most usual earthing system in the world, with the Electricity Supply Company providing an earth terminal at the incoming mains position
TN-S System
51
The following are gapped surge arresters type except a) Valve Arrester b) Expulsion Arrester c) ZnO Surge Arrester d) Spark Gap Arrester
c) ZnO Arrester
52
Useful life of Metal Oxide Varistors is largely dependent on magnitue of
Current
53
Level of current through a body that would cause possible suffocation
30 mA
54
Use to reduce the steepness of wave fronts to protect turn to turn insulation from surges applied to or reflected within machine windings
High Voltage Surge Capacitors
55
The recommended minimum protective margin for lighting and switching surges in insulation coordination is
1.15 and 1.20
56
The insulation is unusual, because combined neutral and earth wiring is used in both the supply and within the installation itself
TN-C System
57
Electric shock severity is dependent on except a) Length of time current flows b) Path of current through the body c) Amount of current through body d) Temperature of body
d) Temperature of body
57
Voltage variations can be designated as follows except a) instantaneous b) momentary c) steady d) temporary
c) steady
58
Transients can be classified as impulsive and ________
oscillatory
59
A protection device which reduces the steepness of wave frof a surge
surge absorber
60
Consist of two 1.5cm rods which are bent at 90 degree angle with a gap in between
Rod gap arresters
61
A protective device which conducts the high voltage surges on the power system to ground
Surge diverter
62
Color of neutral conductor in 120/240 V single phase circuit
White
63
Current to which sensation can be felt
1mA
64
Maximum length to which grounding is tap to water pipe insude building
10ft
65
Maximum length of grounding conductor for cable and primary protection
6m

Midterms (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions