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AREA 3 > Farm Electrification > Flashcards

Farm Electrification Flashcards

1
Q

Electrons found in the outermost shell or orbit of an atom

A

Valence electrons

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2
Q

Classification of materials according to conductivity

A

Conductor - 3 or less valence electrons
Semi-conductor- Has exactly 4 valence electrons
Insulator - 5 or more valence electrons

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3
Q

Unit of potential difference which is equal to one joule of work done per one coulomb of charge

A

Volt

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4
Q

Unit of charge flow equal to one coulomb of charge pass a point in one second

A

Ampere

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5
Q

Ampere formula

A

I=Q/t

I- current
Q- number of charges past
t- time(seconds(

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6
Q

Specific heat capacity of water

A

4, 186 J/kg-°C

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7
Q

Energy required to hit the watuer formula

A

Q= m×c×change in temperature

m= mass of water
c= specific heat capacity of water (4, 186 J/kg-°C

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8
Q

The property of a substance or material which opposes the flow of electrons or current

A

Resistance

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9
Q

Is the measure of materials ability to conduct electric current

A

Conductance or electrical conductivity

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10
Q

Unit of conductance

A

Siemens

G= 1/R

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11
Q

Area of Circular Mil formula

A

A= d²

A= Ara (CM)
D= diameter (mills)

1 inch= 1000 mils
1 MCM= 1000 CM

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12
Q

Reciprocal of impedance

A

Admittance

Unit - Siemens

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13
Q

The joint effect of combining resistance and reactants in an ac circuit

A

Impedance

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14
Q

The voltage and the circuit are in phase

A

Unity power factor

Lagging pf – the current lags the voltage by an acute angle θ.
Leading pf – the current leads the voltage by an acute angle θ.

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15
Q

Ratio of the true power to the apparent power and also defined as ratio of the resistance to the impedance

A

Power factor (Pf)

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16
Q

A circuit phenomenon wherein the inductive reactance and capacitive reactants are equal

A

Resonance

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17
Q

Outer covering of the DC generator wherein the poles are bolted and it is made from cast iron or cast steel

A

Yoke or Frame

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18
Q

Machine that drives the generator

A

Prime mover

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19
Q

Is a device that transfers electrical energy from one electric circuit to another without a change in frequency

A

Transformer

  • Only voltage changes
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20
Q

A winding that forms a loop as it expands around the armature core and is suitable for high current dc generator

A

Lap winding

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21
Q

Used to connect the external load to the armature and made of carbon or graphite and are held in position by spring pressure

A

Brushes

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22
Q

Consists of hard drawn copper conductors insulated from each other and also called mechanical rectifier

A

Commutator

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23
Q

A type of DC generator wherein it’s field winding is excited from its own generated in the armature

A

Self-excited generator

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24
Q

Number of parallel paths in different types of windings

A

Lap winding - a = Pm
Wave winding - a = 2m
Frog leg winding - a = 2pm

Where: a- no of parallel paths
P- no of poles( even numbers)
m- multiplicity factor
simplex- 1, duplex - 2, triplex- 3
and quadroplex- 4

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25
Q

Acombination of both lap and wave windings

A

Frog-leg windings

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26
Q

A winding that forms a wave as it expands around the armature core and suitable for high voltage dc generators

A

Wave winding

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27
Q

Percent rise in the voltage at the terminal of a generator when the load is removed

A

Voltage regulation

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28
Q

A type of DC generator wherein its field winding is excited from a separate external source such as battery or another generator

A

Separately excited generators

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29
Q

Opened wire of low melting point commonly used in the safety of powers switch

A

Fuse wire or fuse

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30
Q

Is enclosed in porcelain or rubber commonly used in various electrical appliances

A

Plug fuse

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31
Q

Fuse that is enclosed and insulating tube

A

Cartridge fuse

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32
Q

An over current protective device with a circuit opening fusible element which opens or breaks when there is an over current in the circuit

A

Fuse

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33
Q

Any current in excess of the rated capacity of the equipment or rated ampacity of the conductor

A

Over current

34
Q

Uses dry and compressed air to extinguish the arc

A

Air-blast CIRCUIT BREAKER

35
Q

Circuit breakers used when interruption occurs in free air

A

Air circuit breaker

36
Q

High voltage fuse specially suited for protecting transformers, capacitor banks, and cables in outdoor distribution substations

A

Power fuse

37
Q

Is a combination of a fuse and a switch used in a primary overhead feeder lines and tap to protect distribution transformers from current surges and overloads

A

Fuse cutout

38
Q

Used to control (switch on or off) the current path in the circuit

A

Switch

39
Q

Converts chemical energy to electrical energy using the chemical materials within the cell to start the action

A

Primary cell

40
Q

It is the combination of cell

A

Battery

41
Q

A single unit of electrolysis

A

Cell

42
Q

A mechanical switching device used to isolate a circuit or an equipment from the supply side

A

Disconnect

43
Q

A special type of switch used in conjunction with three ways switches to control a lamp from three or more different location

A

Four-way switch

44
Q

Type of circuit wiring design for interior use in dry location

A

NM ( non-metalic) cable

45
Q

The modern normally rotates at the same speed as the revolving field in the machine

A

Synchronous motor

46
Q

Design to provide high starting torque for loads with high inertia while requiring very low current

A

Wound rotor

47
Q

A cylindrical shaped cage that fits the shaft with bars extending between its two ends

A

Squirrel cage

48
Q

Must be charged with electrical energy before it can convert chemical energy to electrical energy

A

Secondary cell

49
Q

Single conductors each with its color coded insulation usually used as conduit in houses

A

THHN and THWN

50
Q

A type of non metallic cable design for wet locations and direct burial in the ground

A

Underground Feeder cable

51
Q

Is a is a strong durable thick walled steel tubing made using a hot dip galvanization process to help avoid corrosion

A

Rigid metal conduit or galvanized rigid conduit

52
Q

Type of wiring that features a metal jacket around the wires to protect them from damage

A

Armored cable

53
Q

Holds up well in areas where salty air is a problem including coastal regions

A

Aluminum conduit

54
Q

Is easy to install flexible cost efficient and lighter than other types of conduits

A

Electrical metal conduit

55
Q

Sizing of power fuses

A

For non time delay fuse- size= 300% of Full Load Amperage (FLA)

For time delay fuse- Size = 175% of FLA

56
Q

Sizing power circuit conductors

A

Size= 125% of FLA (full load amperage)

57
Q

Sizing Disconnect switch

A

Size= 125% of FLA

58
Q

Is a thin walled highly flexible pvc conduit that can be bent by hand

A

Electrical Non-metalic Tubing (ENT)

59
Q

Feeder circuit conducts size

A

Conductor size= 125% FLA of largest motor + sum of FLA of remaining motors

60
Q

Sizing of branch circuit conductors

A

125% FLA

61
Q

Thermal relay/overload relay setting

A

Setting= 125% of FLA if the service factor SF= 1.15

Setting= 115% of FLA if service factor SF= 1.0 or not written

62
Q

Used for switching the motor load

A

Magnetic contractor

63
Q

Sizing of circuit breaker

A

Size= 700% FLA (instantaneous trip circuit breaker)

Size= 250% FLA (inverse time circuit breaker)

64
Q

A combination of the arc discharge characteristics of the fluorescent lamp and the shape of an incandescent lamp

A

Mercury lamp
- requires ballast and a certain warm-up period before discharging

65
Q

The most energy efficient lamp up to 200 lumens per watt

A

LED Lamp

66
Q

One of the most commonly used lamp which consumes lesser energy that an incandescent lamp

A

Fluorescent lamp
- pleasant light
-noisy due to ballast hum

67
Q

The least efficient lamp around 14 lumens per watt

A

Incandescent lamp

68
Q

Sizing power of feeder protective device

A

Size= largest motor protective device+sum of FLA of the remaining motors

69
Q

Illumination equation

A

E = F/A

where:

E- illumination
F- Luminous flux (Lumen)
A- Area, m²

70
Q

The intensity of light per unit area

A

Illumination

71
Q

Special type of incandescent lamp known as quartz lamp

A

Tungsten Halogen Lamp

72
Q

Luminous effeciency equation

A

LE= F/P

Where:
F- Luminous flux (Lumen)
P- Power input of light source (watt)

73
Q

Amount of luminous flux it radiates per what of power input

A

Lumens effeciency

74
Q

Luminous intensity equation

A

I= F/w

Where:
F- Luminous flux (lumen)
w- solid angle (steradian)
= 4π(solid angle)

75
Q

Illumination on surface formula

A

E= Icos(angle)/r²

Where:
I- luminous intensity (candela)
r- distance of the light source to point p (m)
angle- angle of incidence

76
Q

Zonal cavity or average illumination method formula

A

Eave= F×N×Cu×Df/A

Where:

F- Lumens output per lamp (lumens)
N- Number of lamps
Cu- coefficient of utilization
Df- depreciation factor
A- surface area illuminated, m²

77
Q

Solid angle equation

A

w= A/R²

Where:
A- surface area, m²
R- distance from the point of observation (m)

78
Q

Three dimensional equivalent of a face angle expressed in steradians

A

Solid angle

79
Q

The unit of magnetic flux in SI is

A

Weber

80
Q

A small lamp used to indicate that a circuit
is energized.

A

Pilot lamp

81
Q

An instrument that measures the voltage
or electrical pressure in a circuit

A

Voltmeter

82
Q

A good capacitor has a ____ resistance.

A

very high

AREA 3 (6 decks)

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