Farm Electrification Flashcards by Christian Tagupa

Electrons found in the outermost shell or orbit of an atom

Valence electrons

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Classification of materials according to conductivity

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

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

Volt

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

Ampere

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Ampere formula

I=Q/t

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

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Specific heat capacity of water

4, 186 J/kg-°C

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Energy required to heatt the water formula

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

Resistance

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Is the measure of materials ability to conduct electric current

Conductance or electrical conductivity

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Unit of conductance

Siemens

G= 1/R

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Area of Circular Mil formula

A= d²

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

1 inch= 1000 mils
1 MCM= 1000 CM

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Reciprocal of impedance

Admittance

Unit - Siemens

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

Impedance

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The voltage and the circuit are in phase

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

Power factor (Pf)

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

Resonance

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

Yoke or Frame

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Machine that drives the generator

Prime mover

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

Transformer

Only voltage changes

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

Lap winding

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

Brushes

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

Commutator

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

Self-excited generator

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Number of parallel paths in different types of windings

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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Acombination of both lap and wave windings

Frog-leg windings

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

Wave winding

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

Voltage regulation

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

Separately excited generators

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

Fuse wire or fuse

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

Plug fuse

Fuse that is enclosed and insulating tube

Cartridge fuse

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

Fuse

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

Over current

Uses dry and compressed air to extinguish the arc

Air-blast CIRCUIT BREAKER

Circuit breakers used when interruption occurs in free air

Air circuit breaker

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

Power fuse

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

Fuse cutout

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

Switch

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

Primary cell

It is the combination of cell

Battery

A single unit of electrolysis

Cell

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

Disconnect

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

Four-way switch

Type of circuit wiring design for interior use in dry location

NM ( non-metalic) cable

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

Synchronous motor

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

Wound rotor

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

Squirrel cage

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

Secondary cell

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

THHN and THWN

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

Underground Feeder cable

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

Rigid metal conduit or galvanized rigid conduit

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

Armored cable

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

Aluminum conduit

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

Electrical metal conduit

Sizing of power fuses

For non time delay fuse- size= 300% of Full Load Amperage (FLA) For time delay fuse- Size = 175% of FLA

Sizing power circuit conductors

Size= 125% of FLA (full load amperage)

Sizing Disconnect switch

Size= 125% of FLA

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

Electrical Non-metalic Tubing (ENT)

Feeder circuit conducts size

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

Sizing of branch circuit conductors

125% FLA

Thermal relay/overload relay setting

Setting= 125% of FLA if the service factor SF= 1.15 Setting= 115% of FLA if service factor SF= 1.0 or not written

Used for switching the motor load

Magnetic contractor

Sizing of circuit breaker

Size= 700% FLA (instantaneous trip circuit breaker) Size= 250% FLA (inverse time circuit breaker)

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

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

The most energy efficient lamp up to 200 lumens per watt

LED Lamp

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

Fluorescent lamp - pleasant light -noisy due to ballast hum

The least efficient lamp around 14 lumens per watt

Incandescent lamp

Sizing power of feeder protective device

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

Illumination equation

E = F/A where: E- illumination F- Luminous flux (Lumen) A- Area, m²

The intensity of light per unit area

Illumination

Special type of incandescent lamp known as quartz lamp

Tungsten Halogen Lamp

Luminous effeciency equation

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

Amount of luminous flux it radiates per what of power input

Lumens effeciency

Luminous intensity equation

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

Illumination on surface formula

E= Icos(angle)/r² Where: I- luminous intensity (candela) r- distance of the light source to point p (m) angle- angle of incidence

Zonal cavity or average illumination method formula

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

Solid angle equation

w= A/R² Where: A- surface area, m² R- distance from the point of observation (m)

Three dimensional equivalent of a face angle expressed in steradians

Solid angle

The unit of magnetic flux in SI is

Weber

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

Pilot lamp

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

Voltmeter

A good capacitor has a ____ resistance.

very high