Selection for Street Light Luminar-(PART-3)
Type of Street Light Lamp:
- Street lighting Lamps normally used three types High intensity discharge (HID) lamps, High pressure sodium vapor (HPSV), Metal halide (MH), or Mercury vapor (MV).
- However Mainly Lamps for Street lighting can be divided into three main categories (1) incandescent lamps and (2) luminescent gaseous discharge lamps. (3) LED
- The lamps used in street lighting today are mostly High Intensity Discharge (HID) lamps that include high pressure sodium, low pressure sodium, high pressure mercury and metal halide lamps.
- In order to reduce the emission of greenhouse gases, the use of energy efficient lamps such as Light Emitting Diodes (LED) for Street lighting has increased.
(1) Incandescent (INC):
- The incandescent or filament lamp was for many years the most commonly used. However, its low efficacy and short rated life have made it undesirable for new installations.
- Advantage:
- Inexpensive
- Available in Different Configurations & Colors
- No warm up is required
- Easily controlled
- Dis Advantage:
- Inefficient ( 10-25 lumens/watt )
- Short lamp life
- Vibration sensitive
- Over-voltage sensitive
(a) Fluorescent (FL):
- At many places tube lights are used for Street Light lighting.
- Tube lights in general are available in lower wattages and they cannot produce the same kind of brightness as a Halogen or Sodium Vapour lamp. So they should not be used to replace Halogen lamps, as they cannot produce the same amount of brightness
- Lamps are available in the following configurations: T5,T8,T10,T12,T17
- Standard Fluorescent Lamps T8 Lamps: 32W and 55W
- Typically used with electronic ballast
- Standard Fluorescent Lamps T5 Lamps: 14W, 21W, 24W, and 35W
- Typically is used with electronic ballast
- Standard Fluorescent Lamps T12 Lamps: Standard lamp wattages
- Advantages
- Efficient(75+ lumens/watt)
- Available in many configurations
- Desirable colors available (2,700K to 4,100K)
- Long life (6,000 –20,000 hours)
- Disadvantages
- Require a ballast
- Temperature sensitive
- May require special controls
(b) Tungsten-Halogen Lamps:
- Halogen lamp is incandescent Type lamp. It has a tungsten filament filled with halogen gas.
- Advantages
- More compact
- Longer life
- More light
- Whiter light (higher color temp.)
- Disadvantages
- Cost more
- Increased IR
- Increased UV
- Light Color: Whit Yellow ,light Blue Color
- Efficiency: Poor Efficiency (10 to 18 lumen/Watt)
- Lamp Life: Long Life ( 2400 Hours)
- Initial Cost: High initial Cost
- Warm up Time:
Application: For outdoor areas/ parking lot lighting
(2) High Intensity Discharge (HID) Lamps:
- HID lamps in general require an external ballast to operate. HID lamps usually take between 1 and 5 minutes to reach full brightness, and if there is a dip in electricity, these lamps will shut off.
- HID lamps must cool sufficiently to re strike, which usually takes from 1 minute to 10 minutes.
- There are Mainly Two type of High discharge lamp
- (1) High Pressure Lamp (HP)
- (A) Mercury Vapor Lamp(MV)
- (B) Metal Halide Lamp
- (C) Sodium Lamp
- (2) Low Pressure Lamp (LP)
- (a) Mercury Fluorescent Tube
- (b) Sodium Lamp
- Ballasts, which are required by both fluorescent and HID lamps, provide the necessary circuit conditions (voltage, current, and wave form) to start and operate the lamps.
- HID Lamps Characteristics
- All HID lamps utilize an internal arc tube and outer envelope construction
- All HID lamps require ballast for operation.
- All HID lamps require warm up period
- All HID lamps require cool-down period before they can re-strike
(A) High Pressure Mercury Vapor Lamps (HPMV):
- It is oldest Type of Lamp in HID Type.
- Prior to the introduction of HPS lamps, MV was the most commonly used light source in highway applications. The MV lamp produces a bluish white light and is not as efficient as the HPS lamp.
- Lamp sizes: 50,70,100,150,175,200,250,350, 400, and 450W
- Advantage:
- Mercury vapor lamps can provide certain low cost options for replacing less efficient lamps such as incandescent lamps without changing the fixtures.
- Pulse start MH lamps utilize an improved ballast design to improve operation.
- Higher efficacy
- Faster warm-up and re-strike longer life
- Better color uniformity
- Energy & maintenance savings (15%)
- Disadvantages:
- Due to their lower efficacy and poor color rendition they are seldom used in new construction. Color shift toward the end of lamp life
- Some lamps are designed for enclosed fixtures only
- Orientation sensitive ( horizontal vs. vertical )
- Light Color: Bluish white ,Pale Blue-Green Color
- Efficiency: Lowest Efficiency in HID Type (30 to 65 lumen/Watt)
- Lamp Life: Long Life ( 2400 Hours)
- Initial Cost: Low initial Cost
- Warm up Time: Faster warm-up and re-strike longer life
- Application: For outdoor areas/ parking lot lighting ,farm light, fish pond
(B) High Pressure Metal Halide lamps (MPMH):
- MH lamps produce better color at higher efficiency than MV lamps. However, life expectancy for MH lamps is shorter than for HPS or MV lamps.
- They also are more sensitive to lamp orientation than other light sources.
- Metal Halide bulbs are as energy efficient as Sodium Vapour lamps.
- Metal halide lamps are similar in construction to MV lamps. Some MH lamps can be operated off Mercury Vapor ballasts.
- MH lamps offer a number of advantaged over MV lamps.
- Light Color: A crisp clear white lights
- Efficiency: Quit Efficient (80 lumen/Watt)
- Lamp Life: Less (6000-20000 hrs)
- Warm up Time:2-3 minutes, hot re-strike 10-20 minutes.
- Application: It is used where color rendering is critical, such as car lots, service stations, athletic fields, industrial manufacturing.
(C) High Pressure Sodium Vapor Lamp (HPSV):
- High pressure sodium lamps are used for both interior and exterior applications and mainly used for street lighting.
- HPS is higher efficient and better choice than metal halide for street light applications.
- HPS is the energy efficient options for halogen lamps as they provide double the amount of brightness for the same amount of wattage.
- HPS lamps differ from mercury and metal-halide lamps because HPS do not contain starting electrodes, the ballast circuit includes a high-voltage electronic starter.
- The arc tube is made of a ceramic material
- Advantages:
- If a Halogen is replaced with Sodium Vapour lamp, 20-25% savings can be achieved.
- Disadvantages:
- Their brightness is highest in the canter (just below the pole) and is lesser on the outside
- Light Color: golden-yellowish-White, Orange color light.
- Advances in electronics now make it possible to dim HPS fixtures in a cost effective manor such as production areas and warehouses.
- Efficiency: Quit Efficient (80 to 100lumen/Watt)
- Lamp Life: Long Life (2400 Hours)
- Warm up Time: 10 minutes, hot re-strike within 60 seconds
- Operating sodium at higher pressures and temperatures makes it highly reactive
- Application:Mostly use on Street lighting.
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