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Year 2 Electrical > Year 2 I1 > Flashcards

Year 2 I1 Flashcards

1
Q

cornea

A

light enters the eye through the transparent outer membrane surrounding the eye

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2
Q

Describe: the retina

A

passes through the focusing lens, and strikes the retina for form the optical image pattern

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3
Q

Describe: the iris

A

(coloured portion of the eye) acts as a diaphragm to expand or contract the pupil.

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4
Q

Describe the pupil

A

controls the amount of light that is allowed to enter the eye

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5
Q

List four factors affecting visibility

A

size
brightness
contrast
time

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6
Q

wavelengths of visible light

A

from 380 nm to 760 nm

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7
Q

human eye is most responsive to

A

555 nm or yellow-green colour range

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8
Q

Colour Temperature

A

or chromaticity is expressed in degrees Kelvin but not a measure of temperature, but rather a measurement of light quality
Low colour temp = warm colour below 3000K
High colour temp = cool colour above 4000K

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9
Q 
Color Rendering Index (CRI)
75-100 Excellent
60-75 Good
50-60 Fair
0-50  Poor
A

the ability of a light source to portray the colour appearance of objects accurately
Value from 0 to 100 where 100 is the best

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10
Q

List 2 Light measurements

A

Luminous Flux quantity of light output

Luminous Flux density is the density of light flux or illumination

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11
Q

1 Lux

A

is equal to 1 lumen per square metre

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12
Q

Lighting equation 1

Inverse square law

A 
E = l/d^2
E = illumination in lux
l = light intensity in candela
d = distance in metres
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13
Q

Lighting equation 2

Cosine law of incidence

A

E = (I/d^2) x cos(theta)

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14
Q

Luminous efficacy

A

is the ratio of the light output (lumens) to the power input (watts) Lm/W
with no losses 1 watt would produce about 683 Lumens

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15
Q

List three factors that affect the Quality of light

A

Glare
Diffusion
Colour

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16
Q

Two of the main causes of light loss

A

Lamp lumen depreciation

Luminaire dirt depreciation

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17
Q

Light Shapes

A

Straight side = S Tubular = T
Flame = F Pear-shaped = PS
Globular = G Parabolic = PAR
Standard line = A Reflector = R

18
Q

Edison base

A

most common screw type

19
Q

Tungsten-halogen lamp

also called quartz halogen or quartz iodine

A

compact high-intensity
white light output
Used for projection, automotive, photocopying and floodlights
contains halogen gas the aids in the regenerative cycle
Lamp life 2500-3000
operates at 5 to 6 atmospheres must be contained in case lamp shatters

20
Q

Ballast function

A

provides the high starting voltage to ignite the tube
limits the current in the tube once the tube lights
in some short tubes only limits the current

21
Q

Fluorescent lamps are measured in 8ths

A

T8 is 8 8ths or 1 inch in diameter

22
Q

CFL

A

compact fluorescent lamp

can be used for replacement of a incandescent lamp

23
Q

Stroboscopic effect of fluorescent lamps

A

makes rotating machine appear stopped
use lead-lag ballasts operating in twin-lamp fixtures
connect lamp fixtures on different phases of a three phase system
electronic ballasts eliminates this

24
Q

Fluorescent lamps are classified

A

according to their start methods
preheat start not used much
instant-start
rapid-start

25
Q

Instant start or cold-cathode starting

A

has a step-up transformer to a sufficient magnitude to not have to pre-heat the cathode

26
Q

Slimline fluorescent is a instant-start

A

that has a switch incorporated in one of the lamp-holder sockets so that high voltage will not be present until lamp is fully seated

27
Q

Rapid-start cct fluorescent

A

eliminates three major shortcomings
large, heavy ballast
high strike voltage
longer lamp life due to lower strike voltage

28
Q

Electronic ballasts

A

take low-frequency AC convert to DC convert to very-high-frequency AC. above 20kHz
caution shock hazards high voltages can be above 347 V

29
Q

the wire used for end to end fluorescent fixtures install

A

must be not less than 600 V rated and 90 degrees Celsius

30
Q

List three types of HID lights

A

High-intensity discharge
Metal halide
Mercury vapour
High-pressure sodium

31
Q

Describe Mercury Vapour Lamp

A

Must have ballast to strike small arc that vapourizes the mercury and permits striking of the main arc.
3 to 7 min starting
Restart - restrike time is 4 to 6 min
24000 hour plus operation
have a phospor coating that improves the colour by converting some UV radiation to visible light
Letter code is H for Hg

32
Q

Describe Metal halide lamps

A

Shorter arc tube than Mercury vapour
contains additional compound metals and halogen gas that improves efficacy and colour rendition of the lamp.
first choice for good colour redition
startup is 5 to 7 min
restart and restrike can be as long as 15 min
Shorter life span 15000 hrs
letter code is MD or M

33
Q

Describe High-pressure sodium lamp

A

HPS different in that it has no starting electrode
An arc tube that contains xenon gas and sodium-mercury amalgam
Special circuitry in the ballast provides arc strike or 2500 v or more
startup time of 3 to 4 min warm golden white
restrike time is usually less than a min
rated lifespan is 24000
can operate in any position without adverse effects on bulb
letter code is S

34
Q

Letter shape codes for HID

A 
B = bullet
BT = bulged-tubular
E = elliptical
PAR = Parabolic aluminized reflector
T = tubular
35
Q

H36BT-1000/DX

A 
H for mercury vapour 
36 for ballast type
BT for shape
1000 for wattage
DX for colour Deluxe colour
36
Q

HID Reactor ballast

A

only used with H and sometimes called a lag reactor ballast
works only when supply voltage is high enough to strike an arc
acts only as a choke
seldom used in new install

37
Q

HID Autotransformer ballast

A

lag autotransfromer ballast PF .9
used with H lamps
can not be used when supply voltage varies beyond plus or minus 5%
to low or variations of voltage can keep lamp from striking

38
Q

HID auto-regulator ballast

A

constant wattage autotransformer ballast (CWA)
With the combination of capacitor and autotransformer (reactor) give a PF .95
can handle voltage fluctuation of 40 to 50 % without extinguishing the lamp
taps for two or more supply voltages
used for all HID but most common for MH

39
Q

HID regulator ballast

A

secondary windings are electrically isolated from the supply windings
superior to autotransformer in that it can hand plus or minus 13 % and voltage dips of up to 50 to 60%
larger and more expensive

40
Q

HID HPS ballast

A

supplies high-voltage spike to augment the starting voltage because HPS bulb has no starting electrode.
Electronic starting aid provided pulsed voltage with a peak of 2500 to 4000V

Year 2 Electrical (9 decks)

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