Pretest Module 15 Units 1, 2, 3, 4

Transcription

1 Pretest Module 15 Units 1, 2, 3, 4 1. What is the light-sensitive surface at the back of the eye? Retina 2. What is the transparent outer membrane surrounding the eye? Cornea 3. What four objective factors affect visibility? Size, brightness, contrast, and time. 4. What two factors determine brightness? Intensity of light striking the object and the amount of light reflected towards the eye. 5. What is the result of working in poor light conditions? Eye strain and discomfort. 6. What is the wavelength for visible light? nanometers. 7. What is the result of a light source emitting radiant energy balanced in all visible wavelengths? White light 8. What colors are the human eye most responsive to? Yellow green range. 9. What are the primary colors? Red, green, and blue. 10. Color temperature is a measure of what? Light quality 11. What is color rendering? How well colors look compared to natural light. 12. What are the two most fundamental measurements dealing with light? Total light output from the source and light at the worksurface. 13. What is luminous flux? Quantity of light output from source. 14. What is luminous flux density? Density of light measured on a surface. 15. What is the formula for the relationship between foot-candles and Lux? 1fc=10.76Lux 16. What is the inverse square law? Illumination is inversely proportional to the square of the distance from the source. 17. What is the angle of incidence? Angle at which the light hits the surface.

2 18. What is luminous efficacy? What is the unit of measurement? Ratio of light output compared to power input or lumens/watts. Lumens per watt. 19. What two basic considerations are involved in the design of any lighting system? Area-type of environment and tasks to be performed. 20. What factors affect the quality of light? Glare, diffusion, and color. 21. What are the parts of a luminaire? Lamps, wiring channel, reflectors, lense, diffusers, and control gear. (Ballast) 22. What is a luminaire distribution curve? Charts that illustrate variation in light intensity through a vertical axis. 23. What are the two main causes of light loss over time? Lamp lumen depreciation and luminaire dirt depreciation. 24. What percentage of light loss can be attributed to dirty bulbs? 30% Unit 2 1. What is the oldest form of lighting? Incandescent 2. How efficient is an incandescent light source? 10% 3. What material is used for the filament in an incandescent light? Tungsten 4. What is the purpose of the gas in an incandescent bulb? Reduce filament evaporation 5. What is the difference between the glass in an incandescent bulb and a quartz bulb? Much higher temperature glass for quartz. 6. What does the T stand for in a F40T12 lamp? Tubular 7. What does the 8 mean in a F20T8 lamp? Diameter in 1/8s of an inch.

3 8. What two gasses are present in an incandescent bulb? Nitrogen and argon. 9. What is the purpose of a button rod in an incandescent bulb? Support for button. 10. What letter is used to designate the shape of the standard light bulb? A 11. What shape is a F shaped bulb? Flame 12. What is the purpose of diffuse glass? Reduce brightness. 13. What is the purpose of acid etching on a bulb? Reduce brightness. 14. What color is the light produced by a colored filament bulb? Same as normal bulb contains all colors. 15. What is the most common type of lamp base? Medium 16. What type of base is used for most lamps over 300 W? Mogul 17. What type of base is used for most lamps under 300 W? Medium 18. Where are candelabra intermediate bases typically used? Chandeliers and specialty lighting. 19. Why is the grounded conductor typically connected to the screw shell of the lampholder? Minimize shock hazard. 20. What type of base is typically used for lamps where accurate filament positioning is required? Prefocus and bayonet. 21. Where is a three-contact screw base used on a bulb? Tri-lite lamps. 22. Will two 100W bulbs produce more light than a 200W bulb? No 23. Why is there a steady reduction in light output for incandescent bulbs? The filament deteriorates gradually and deposits on the inside of the glass. 24. What position is most efficient for burning incandescent bulbs? Base up.

4 25. What is the effect of increased voltage on incandescent bulbs? Higher output but shorter life. 26. What is different about a rough service lamp? Thicker filament reduced output. 27. Which lamp is best suited for projection and photocopying? Tungsten-halogen 28. What type of gas is in a tungsten-halogen lamp? Halogen (Iodine or bromine) 29. What is the regenerative cycle of a lamp? Halogen gas mixes with the tungsten on the glass and drifts back to the filament. 30. Why must the filament be close to the glass in a tungsten-halogen lamp? Glass must be very hot to aid regeneration process. 31. Which type of lamp is best for suited for automobile headlamps? Tungstenhalogen 32. Is the color rendition of the lamp in question 31 good or bad? Good 33. What is the purpose of the second glass envelope in a tungsten-halogen lamp? It is a safety precaution in case the inside glass shatters under pressure. 34. Why are tungsten-halogen lamps not recommended for dimming? It will reduce temperatures which will affect the regenerative process. 35. What precaution should be taken when installing or removing tungsten-halogen lamps? Do not touch glass with fingers, be sure bulb is off before removing, use only in proper fixture type. 36. What is the most common method of controlling incandescent lamps? Switch. 37. How many three-way and four-way switches are required to switch a light from three locations? Two three-way and one four-way. 38. What is the unique terminal on a three-way switch called? Common

5 39. What are the two wires called that connect between two three-way switches? Travellers 40. What is the most common dimmer switch? Rotary 41. Where is the relay mounted in a low-voltage relay control system? Lamp outlet box. 42. What voltage does a low-voltage relay control system operate on? 24V 43. What are some advantages of low-voltage relay control of lights? Ease of adding switches, Lower (safer) voltage at the switch, and inexpensive wiring. 44. How are switches connected to each other in a low-voltage relay control system? Parallel 45. What type of switch is used with low-voltage relay control systems? Single-pole, double-throw, momentary contact. 46. What device is used when a large number of lights or large loads are to be controlled from a single device? (photocell or time clock) Relay or contactor. 47. What is the difference between a lighting contactor and a motor starter? Overloads on a motor starter. Unit 3 1. Which type of lighting is a two-stage process? Florescent-current flow in a gas produces invisible light. The coating changes invisible light to visible light. 2. How is invisible ultraviolet radiation converted to visible light in a fluorescent bulb? By the coating on the glass. 3. What two gasses are typically found in a fluorescent tube? Argon or krypton. 4. What material (other than gasses) is found in fluorescent tubes? Mercury.

6 5. What determines the color of light in a fluorescent light? Type of phosphor used. 6. What are the two functions of a ballast? Provide high voltage to strike arc and limit current once the arc is struck. 7. When is it possible that the supply voltage may be high enough to strike an arc in a fluorescent tube? (Without ballast) Short tube. 8. What is the diameter of a T5 lamp? T12? 5/8 and 1 ½ 9. What material is used to coat the inside of fluorescent tubes? Phosphor 10. What are some of the standard fluorescent bulb shapes? U shaped, circline, and compact. 11. What are the three most common pin types for fluorescent tubes? Bi-pin, Singlepin and recessed double contact. 12. What is the advantage of having fluorescent lamps on for a minimum of 10 hours at a time? 30% longer life. 13. What factors affect the life of fluorescent bulbs? Frequent switching, wrong ballast, high voltage, and losing cathode pre-heat during startup. 14. What is seasoning for fluorescent bulbs and how long does it take? Breaking in period where light output decreases rapidly for about first 100 hours. 15. How does ambient temperature affect light output in fluorescent lights? Decreases, quickly in low ambient but slower in high ambient. 16. What ambient temperature are standard fluorescent lights designed to work best in? 20 0 C 17. What is the major cause of ballast failure? High ambient temperature.

7 18. What do the letters A-F represent on a ballast? Sound rating with A being the quite one. 19. What do the letters HO indicate on a ballast or lamp? High Output 20. What is the main problem with energy efficient lamps? Slightly less output. 21. What is stroboscopic effect and how can it be eliminated? High frequency flickering that makes moving objects appear stopped. Use lead-lag ballast or connect fixtures to two different phases of power so they reach peak at different times. 22. What is the danger of stroboscopic effect? Someone could be hurt assuming a machine is stopped when it is still running. 23. What is the most efficient light source available? Low-pressure sodium. 24. Low-pressure sodium lights fit into which category of lighting? It s own. 25. What is the efficiency of the most efficient lighting available? 200 lumens-perwatt. 26. What temperature is the outer glass in a low-pressure sodium fixture? Warm but not hot. 27. How is the color rendition of low-pressure sodium lamps? Poor 28. What is the average life of a low-pressure sodium bulb? 18,000 hours. 29. How is light output affected as a low-pressure sodium bulb ages? May increase slightly. 30. What precautions should be taken when disposing of low-pressure sodium bulbs? Consider hazardous material. Treat accordingly.

8 31. What are the three types of fluorescent lights? Preheat, Instant-start, and rapidstart. 32. Which device is in a preheat lamp but not any other type of fluorescent fixture? Starter. 33. How have the preheat fixtures been revived? Compact fluorescents. 34. How much voltage is typically required to start an arc in an instant-start fixture? V 35. How is a person changing a bulb protected from the high starting voltage in an instant-start fixture? Switch in the lampholder socket. 36. What are the advantages of the rapid-start fixture? Smaller ballasts, lower voltage, and longer bulb life. 37. Why does the rapid-start fixture require more time to start than an instant-start? Momentary preheat in the cathodes. 38. In a two tube rapid-start fixture, how are the lamps connected? (parallel or series) Parallel on one end. 39. What type of voltage and frequency conversion takes place in an electronic ballast? AC to DC then DC to high-frequency AC. 40. Why are electronic ballasts more efficient than transformer ballasts? Higher power conversion efficiency. Less wasted heat. 41. What frequency do electronic ballasts operate on? Above 25KHz 42. What are the disadvantages of electronic ballasts? Expensive, shorter life expectancy, Power quality issues, and hazardous voltages.

9 43. What precaution must be taken when installing contactors for fluorescent lighting? Rated twice amperage of the lamps they control unless approved for the purpose. 44. What precautions must be taken when using a lighting fixture as a raceway? Minimum 600V and 90 0 C 45. How are faults typically diagnosed in a fluorescent fixture? Substituting good parts. 46. How is the open circuit voltage of a ballast typically checked? Voltmeter. 47. How does a rise in ambient temperature affect a ballast? 10 0 rise will cut life in half. 48. What is the typical cathode heater voltage for a fluorescent fixture? 3-4V 49. How is the starter in a preheat fixture typically checked? Replace with a good one. 50. What are some of the results of using improper lamps for a fixture? Damage, reduced output, reduced lamp or ballast life. 51. What are the possible causes of a very slow starting fluorescent fixture? Low voltage, poor lamp to lamp connections, defective starter, defective lamps, or low or high bulb temp. Unit 4 1. What is the difference between a high-pressure sodium lamp and a low-pressure sodium lamp or fluorescent lamps? Shorter arc-tube and higher temperature and pressure.

10 2. Which two HID lamps are most common today? Metal-halide and High-pressure sodium. 3. Where is the date typically found on HID lamps? Stamped on the base. 4. Once a mercury vapor lamp has been lit and goes out, what two things must take place before the arc will strike again? Lamp cools and pressure reduces. 5. Which mercury vapor lamps have the highest efficiency? Higher wattage. 6. What is the average life of a mercury vapor lamp? 24,000 hours 7. What lamp position is most efficient for mercury vapor lamps? Vertical 8. What modification must be made to a mercury vapor fixture when the ambient temperature is below freezing? Special Ballast 9. Why should mercury vapor lamps be replaced immediately if cracked or broken? Produces UV light which can cause burns. 10. How is the metal-halide lamp different from a mercury-vapor lamp? More efficient, longer restrike, shorter life expectancy, better color rendition. 11. Which HID lamp gives the best color rendition? Metal-halide 12. Which HID lamp lasts longer, metal-halide or mercury-vapor? Mercury-vapor 13. How is a high-pressure sodium lamp different from the other HID lamps? No starting electrode, very high voltage, different gas in the arc tube. 14. What is the value of the voltage spike in a high-pressure sodium lamp? 2500V 15. What type of gas is in a high-pressure sodium lamp? Xenon gas and sodium mercury amalgam 16. What is the best mounting position for a high-pressure sodium lamp? Universal with no adverse effects.

11 17. How is the color rendition of high-pressure sodium lamps? Not good 18. Which HID lamp produces the most lumens-per-watt? 140 lumens-per-watt. 19. Is it a good idea to work on a live high-pressure sodium fixture? Why? No under no circumstances. 20. What shape bulbs are indicated by the letters BT? Bulged tubular. 21. What is the diameter of a BT28 HID lamp? 3 ½ 22. What do the letters BU indicate on the glass of a HID lamp? Base Up 23. What are the two functions of a ballast in a HID fixture? Produce high voltage to start the arc and then limit the current to a reasonable value. 24. Can a lamp of a different type or wattage be used in a HID fixture? No 25. What is the least expensive and most simple ballast for mercury vapor fixtures? Reactor Ballast 26. What is the sole purpose of a reactor ballast and where are they used? To act as a choke and they are used where the supply voltage is high enough to strike the arc. 27. What is the minimum supply voltage for a reactor ballast? 240V 28. What is the advantage of the autotransformer ballast over a reactor ballast? It can be used on voltages above or below the required starting voltage. 29. What is the advantage of the auto-regulator ballast over the autotransformer ballast? Maintains lamp current at a fixed value regardless of variations in voltage. 30. Which type of ballast is typically used with metal-halide lamps? Auto-regulator 31. What is the advantage and disadvantage of the regulator ballast? Can withstand voltage drops of 50-60%. Larger and more expensive.

12 32. What are the advantages and disadvantages of the series and lead-lag two lamp ballasts? Reduces size and cost of ballast for 2 light fixture. Series connection will not allow one light to operate if the other is out but is cheaper. 33. Which ballast for HID lamps has an electronic starting aid? HPS 34. What is one sign that a high-pressure sodium lamp is near the end of its life? Cycling on and off. 35. Why should a ballast for a high-pressure sodium fixture be mounted near the lamp? Starting spike attenuates with distance. Distorts. 36. What is polarization of lamp-holders? Connecting the grounded conductor to the pin and not the shell. 37. When is the screw-shell of the lamp-holder not required to be grounded in a HID fixture? When a ballast supplies two lamps in series only one shell needs to be grounded. 38. What are the reasons for mounting ballasts in a location away from the fixture? Lower noise or ambient temperature.