Power Engineering Book 2 Part 1 > Unit 3 > Flashcards

Unit 3 Flashcards

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1
Q

What is a luminaire?

A

The complete lighting unit, including the lamp, ballast, and means of light control

A luminaire directs or controls the light produced by the lamp.

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2
Q

What are the functions of a luminaire?(2)

A
  • Direct light
  • Control light produced by the lamp

This can be accomplished using transparent, translucent, or opaque surfaces.

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3
Q

What are the types of surfaces used in luminaires to control light?

A
  • Transparent
  • Translucent
  • Opaque

These surfaces can refract, reflect, or absorb light.

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4
Q

What is a fluorescent troffer?

A

An inverted metal trough mounted in or on the ceiling to form a fixture

It provides direct or indirect lighting.

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5
Q

What are ceiling mount wraparounds?

A

Luminaires with plastic enclosures surrounding the lamp, providing broad light distribution

They are relatively cheap and efficient but may appear too bright in many installations.

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6
Q

What can excessive brightness in a lighting installation indicate?

A

The system may have too many luminaires required in a large installation

This can lead to discomfort and poor lighting quality.

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7
Q

What is the purpose of reflectors in lighting systems?

A

To partially screen the lamps from view

Reflectors serve as shields in lighting design.

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8
Q

What is structural lighting used for?

A

To provide task lighting to supplement ambient lighting

Structural lighting can be integrated into architectural components.

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9
Q

What are the three main types of illumination?

A
  • General (Uniform)
  • Local or Supplementary
  • Combined General/Local (Non-Uniform or Task Lighting)

Each type serves different lighting needs and design considerations.

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10
Q

Define General (Uniform) illumination.

A

A system designed to provide a uniform illumination level throughout the area

It is useful for unpredictable desk locations.

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11
Q

What is the characteristic of Local or Supplementary lighting?

A

Local high-level lighting for a work area without overall uniform ambient lighting

An example is track lighting for wall displays.

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12
Q

Describe Combined General/Local lighting.

A

Provides reasonable ambient lighting while increasing illumination levels for specific task areas

This type is more energy efficient than a uniform system.

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13
Q

What are the advantages of direct lighting?(3)

A
  • More energy efficient
  • Low initial cost
  • Easier to control and direct

Direct lighting directs luminous intensity down toward the work surface.

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14
Q

List the disadvantages of direct lighting.(3)

A
  • Harsh shadows
  • Greater potential for direct glare
  • Excessive luminance ratios on the ceiling

These factors can affect visual comfort.

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15
Q

What are the advantages of indirect lighting?(3)

A
  • Potential for maximum visual comfort
  • Greater direct glare control
  • Produces uniform, diffuse, shadow-free light

Indirect lighting directs luminous intensity upward, reflecting off surfaces.

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16
Q

What is a common misconception about indirect lighting?

A

That it is better for energy utilization than direct systems

Indirect systems are usually less energy efficient than direct systems.

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17
Q

What is the impact of designing a lighting system for energy efficient operation?

A

It has a tremendous impact on costs

Initial, operating, and maintenance costs should all be considered.

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18
Q

What are the types of switches used for on-off control?(5)

A
  • Single pole
  • 2-pole
  • 3-way
  • 4-way
  • Momentary

These switches are used to control lighting circuits in various configurations.

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19
Q

What is the function of a single-pole switch?

A

Opens only one wire

It has two terminals and is inserted in one of the two wires to turn a lamp on and off.

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20
Q

What is a 2-pole switch used for?

A

To open both wires

It is sometimes required under certain circumstances.

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21
Q

What is required for control from multiple locations?(2)

A
  • Two 3-way switches
  • Remaining switches are 4-way

For example, to control a light from 4 locations, two 3-way and two 4-way switches are needed.

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22
Q

What are the advantages of low-voltage switching?(4)

A
  • Permits local and remote control of lights
  • Reduces costs with control wires
  • Shortens full voltage circuitry
  • Simplifies alteration work

Low-voltage circuits typically operate at 24 V.

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23
Q

What is the importance of centralized control in lighting?

A

Energy conservation

It allows lights in unoccupied spaces to be turned off without physically going to each switch point.

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24
Q

What does the Canadian Electrical Code require for branch circuits?

A

Circuit protection

This is normally accomplished with a circuit breaker.

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25
What is the purpose of **separate switches** in lighting control?
To turn off lights in unoccupied spaces ## Footnote This is best accomplished by having separate switches controlling those lights.
26
What is the primary function of **photoelectric controls**?
Automatic light control ## Footnote Originally used photocells; now commonly use cadmium-sulfide cells.
27
What happens to the **relay contacts** when the illumination level drops below the control setting?
The relay contacts close and the light is energized ## Footnote This is due to the increase in resistance of the cadmium-sulfide cell.
28
What is the purpose of a **timer or time clock** in lighting systems?
Energizes or de-energizes a light at a preset time ## Footnote Basic timers have a single on and off time for each day.
29
What are the benefits of using **carryover springs or back-up batteries** in timers?(2)
* Maintain operation during power outages * Overcome necessity of resetting timers after outages ## Footnote Springs are wound by a small electric motor.
30
What is the function of **occupancy sensors**?
Sense motion to turn lights on and off ## Footnote Can reduce electrical bills by 20 to 60 percent.
31
What are the two most common types of **motion detectors**?
* Infrared * Ultrasonic ## Footnote Infrared detects heat; ultrasonic uses sound waves.
32
What can cause **false triggering** in occupancy sensors?(3)
* Mirrored images * Daylight * Vibrations from air conditioning ## Footnote Important to consider when choosing sensor type and location.
33
What is the most effective means of controlling the **level of illumination**?
Using a dimmer ## Footnote Dimmers can be variable resistors or solid-state types.
34
What is a characteristic of **solid state dimmers**?
Low energy consumption ## Footnote Operate by turning on or off at specific points in the AC wave cycle.
35
What type of dimmers require special dimming controls?(2)
* Fluorescent * High intensity discharge (HID) ## Footnote These dimmers are complex and expensive but can save energy if used properly.
36
What is the purpose of **emergency lighting**?
To provide illumination when the normal source is interrupted ## Footnote Emergency lighting is crucial for safety during power failures or electrical system failures.
37
List the **three situations** that require emergency lighting.
* Interruption of the normal power source * Failure of the building's electrical system * General power failure ## Footnote Emergency lighting systems are defined based on these situations.
38
What are the **three types** of emergency lighting systems?
* Type 1: Covers all three situations * Type 2: Covers situation 2 * Type 3: Covers situation 3 ## Footnote The type of system determines the localization of sensors.
39
Emergency lighting must be provided in places of assembly for **______ or more people**.
300 ## Footnote For assemblies with more than 1000 people, Type 1 emergency lighting is required.
40
What type of emergency lighting is required in structures where **daylight does not penetrate** and have an occupancy of 100 people or more?
Type 1, 2, or 3 ## Footnote This ensures safety in enclosed spaces.
41
All **educational and institutional occupancies** require what type of emergency lighting?
Type 1 or 2 ## Footnote These types are necessary to ensure safe egress in emergencies.
42
Multiple residences with **______ or more dwelling units** require emergency lighting.
25 ## Footnote Types 1, 2, or 3 can be implemented based on the occupancy.
43
Office buildings with occupancy in excess of **______ people** require emergency lighting.
1000 ## Footnote Emergency lighting types 1, 2, or 3 are applicable.
44
What is the **interrelationship** between lighting and air conditioning in buildings?
Lighting can provide **thermal energy** that reduces the need for heating in cold months ## Footnote The thermal energy from light fixtures can prevent the thermostat from calling for more heat.
45
What is the purpose of **heat removal luminaires**?(4)
* Remove heat from lighting systems before it enters occupied spaces * Reduce cooling and ventilation requirements * Improve lamp efficiency and extend ballast life * Save energy by reclaiming heat for other purposes ## Footnote Heat removal luminaires can also enhance the ceiling's appearance by eliminating air diffusers and grills.
46
In large office buildings, approximately **what percentage** of total electrical energy consumption is used by the lighting system?
60% ## Footnote This highlights the substantial portion of the electrical load attributed to lighting in industrial-commercial buildings.
47
Lighting systems should be designed to provide the user with the right quantity and quality of **illumination** for what purpose?
Efficient and comfortable vision ## Footnote Illumination requirements vary based on specific tasks rather than general areas.
48
What can be done to realize **energy savings** in lighting systems?(2)
* Reduce illumination levels in areas adjacent to task areas * Specify the correct level of illumination for specific tasks ## Footnote Circulation areas can have lower lighting levels compared to work areas.
49
What is **lamp efficiency** expressed in?
Lumens per watt ## Footnote Lamp efficiency is a key characteristic that affects the overall performance of lighting systems.
50
What factors influence the **suitability of a lamp**?(4)
* Life * Colour rendition * Cost * Warm-up time ## Footnote These factors must be considered alongside efficiency for optimal application.
51
What are the **types of lamps** mentioned in the text?(4)
* Incandescent lamps * Fluorescent lamps * Mercury vapour lamps * High pressure sodium lamps ## Footnote Each type has different efficiencies measured in lumens per watt.
52
What do **high efficiency ballasts** reduce?
Energy consumption by up to 9% ## Footnote They achieve this by decreasing wattage losses within the system.
53
What is the purpose of **reduced light output ballasts**?
Reduce current to lamps by up to 20% ## Footnote These ballasts should only be used if compatible with lighting needs.
54
What is a key advantage of **solid state ballasts**?
Higher efficiency and lower power usage ## Footnote They are gaining popularity due to their significant energy savings.
55
What does the **coefficient of utilization (CU)** describe?
Percentage of light that reaches the work plane ## Footnote CU is crucial for assessing the effectiveness of lighting installations.
56
What effect does **light-reflecting finishes** have on lighting efficiency?
Higher reflectance increases light on work surfaces ## Footnote Light surfaces reflect more light than dark surfaces, enhancing overall illumination.
57
What can cause the **lighting level** provided by a system to depreciate substantially over time?(4)
* Dirt accumulation in luminaires * Room surface depreciation * Lamp lumen depreciation * Burnouts not promptly replaced ## Footnote These factors contribute to reduced lighting efficiency.
58
In a **group relamping plan**, what is replaced at a preplanned time?
All lamps ## Footnote This method can reduce labor costs by 10% to 25%.
59
The most economical time to relamp is predicted based on the known rate of **burnouts** at a certain point in the life of a group of lamps. What is the typical economical group relamping period?
About 70% of rated life ## Footnote More frequent group relamping can minimize light loss.
60
What significant light losses result from **dirt accumulation** on luminaires?
Light output can drop by 5% per year ## Footnote In dirtier conditions, light loss is correspondingly higher.
61
How often is cleaning of luminaires usually required?
No more than once a year, but no less than once every two years ## Footnote Coordinating cleaning with group relamping may be the most economical solution.
62
What types of controls are available for **automatic switching** of lighting systems?(2)
* Photoelectric controls * Time-switch controls ## Footnote These controls help manage energy use effectively.
Power Engineering Book 2 Part 1
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