Technology

WORKING PRINCIPLE

Induction lamps are basically fluorescent lamps with electromagnets wrapped around a part of the tube. In these lamps, high frequency energy, from the electronic ballast, is sent through wires, which are wrapped in a coil around a ferrite inductor on the outside of the glass tube, creating a powerful electromagnet called an inductor. The induction coil (inductor) produces a very strong magnetic field which travels through the glass and excites the mercury atoms in the interior. The mercury atoms are provided by the amalgam (a solid form of mercury). The excited mercury atoms emit UV light and, just as in a fluorescent tube, the UV light is down-converted to visible light by the phosphor coating on the inside of the tube. The glass walls of the lamp prevent the emission of the UV light as ordinary glass blocks UV radiation at the 253.7 nm and 185 nm range

VISIBLE PERCEPTION OF LIGHT

Many people, who see induction lights, comment on how bright they appear and on what they feel is a higher quality of light being emitted from the fixtures. However, when individuals compare a induction light to a conventional lamp with a light meter, the Induction lamp is generally measured as producing less light than the conventional lamp. This has led some people to question the installation of these fixtures - even though they use 50% less energy - as they expect that the areas lit by them will not be bright enough when compared to conventional lighting. All this, even though their eyes are telling them they are the same if not brighter.

The issue is not with the induction lights and their ability to produce acceptable light. Today's standards for light meters are calibrated using the 1951 CIE Color Space Standards. They have not evolved with advancing technology in the lighting arena. This standard used to set the sensitivity curve for light meters does not take into account the contribution of Scotopic vision (night vision) to the sensitivity of the eye. Scientific studies have shown the eye is more sensitive to blue wavelengths than the measurement curve of the light meter. Blue light, acting on human night vision (scotopic vision) is largely responsible for "visual acuity" or sharpness of vision. Simply put, light meters and the 1951 standards by which they measure light are wrong. Consumers are therefore paying for products with yesterday's lighting quality while not taking advantage of today's products, such as induction lighting that offer reduced costs and a better quality of light.

VISION PARTICULARS

The human retina contains about 125million rod cells and 6 million cone cells. These respond to different frequencies (colors/ wavelengths) of light in different ways. Cone cells are adapted to detect colors and function well in bright light, while rods cell are more sensitive but do not detect color well as they are adapted to low light.

  • .Photopic Vision is the scientific term for human color vision under normal conditions during the day (i.e. human perception of red, green and blue that the brain integrates to form full color images of the world around us.)
  • Scotopic Vision is the scientific term for human visual perception in low light (night vision).
  • Mesopic Vision is the scientific term for the combination between Photopic and Scotopic vision taking into account the total sensitivity of the rod cells in the eye for the blue range, with the color perception of the cone cells.

The ratio of Photopic light vs. Scotopic light in a lamp is called the S/P ratio. This ratio determines the apparent visual brightness of a light source. This is why the 200w lamp will appear as bright or brighter to the human eye than a sodium vapor or metal halide of twice the wattage.

The difference between the light sources becomes clear on superimposing the previous sensitivity curve on the emission spectrum of different lamps. The shaded portion shows the effective useful scotopic component of the emitted light. In other words, more the shaded area, more the visibility for that particular source.

How does it work?: Light is measured in Lumens (Lux or foot Candles). The S/P ratio of a lamp is important as it provides a number that can be used to multiply the output reading of a lamp using a 1951 standard conventional meter to determine how much light, which is useful to the human eye, a lamp produces. These are known as Pupil Lumens (PpLm)

Using a conventional light meter or spectrometer, the light is measured to determine the photopic vision sensitivity curve. Using the same light source with a light meter calibrated to the scotopic, the scotopic sensitivity curve is determined. The resulting readings form an S/P ratio that can be expressed as a Single number. The chart below gives a comparison of Karee Induction Lamps S/P ratio compared to other common industrial lamps. These figures are based on Data received from Francis Rubenstein of Berkley National Library, with the Induction sources marked by arrows.

For Example:

An induction lamp has an S/P ratio of 2.25 for 6500k colour temperature. Accordingly for a 120W induction lamp which has a rated lumen output of 9600 Lumens, the Pupil Lumens would become 9600 x 2.25 = 22950... This gives equivalent visible light compared to a 250 W Metal Halide.

Comparison of Electrical Consumption and Light Output
Lighting Fixture Type: Metal Halide 200W Induction 120W Induction
Lamp Type: M250 200R 120R
Nominal wattage (Watts): 250W 200W 120W
Total actual wattage (Ballast included): 275W 204W 122.4W
Ballast overhead (Watts): 25W 4W 2.4W
Conversion efficiency (Lumens/Watt): 61.8 L/W 81 L/W 80 L/W
Light output (Lumens): 15450 L** 16800 L 9600 L
S/P Ratio (as per data from Lawrence Berkley National Library): 1.49 2.25 2.25
Output corrected for Pupil-Lumens (Lumens): 23,020 L 38,250 L 21,600 L
Approximate light output increase/decrease (%) 0% (base) + 66.1% * -6.1% *
Energy savings (Watts - %): 0W – 0% 71W – 25.5% 152.6W – 55.5%
* Note: A difference of +/- 10 to 15% in light levels is barely perceptible to the human eye - % figures rounded up/down to one decimal place. ** Lumen depreciation in Metal Halide lamps not taken into account.

From, the above it is clear that a 250 W Metal Halide fixture can easily be replaced with a 120W Magnetic Induction Lamp Fixture thereby, reaping a considerable saving in energy costs, while maintaining a similar light level.

For an installation having 100 lights the saving would be 15.26 KW. For a 10 Hours burning cycle and power tariff of Rs. 6 /- approx., the savings per day would be Rs. 916 /- (approx.) giving an annual savings of Rs. 3.35Lacs (approx.)

In addition savings would accrue due to nil replacement cost in the case of Induction Lamps whereas Metal Halide fixtures would need lamp / choke replacements regularly.

Comparative Matrix

Lamp/Ballast Type

Wattage

P.F

System Wattage

Lamp Life

CRI

Mean Lumens

S/P Ratio

Mean Pupil Lumens

High Pressure Sodium

70

0.85

82

10,000

21

5,670

0.62

3,515

High Pressure Sodium

150

0.85

176

10,000

21

14,000

0.62

8,680

High Pressure Sodium

250

0.85

294

10,000

21

25,600

0.62

15,872

High Pressure Sodium

400

0.85

471

10,000

21

45,000

0.62

27,900

Induction

40

0.98

41

1,00,000

85

3,400

2.25

7,650

Induction

60

0.98

61

1,00,000

85

5,100

2.25

11,475

Induction

80

0.98

82

1,00,000

85

6,800

2.25

15,300

Induction

100

0.98

102

1,00,000

85

8,500

2.25

19,125

Induction

120

0.98

122

1,00,000

85

9,600

2.25

21,600

Induction

150

0.98

153

1,00,000

85

12,750

2.25

28,688

Induction

200

0.98

204

1,00,000

85

16,800

2.25

37,800

Metal Halide

150

0.85

176

3,000

65

11,300

1.49

16,837

Metal Halide

250

0.85

294

3,000

65

17,000

1.49

25,330

Metal Halide

400

0.85

471

3,000

65

28,800

1.49

42,912

LED

40

0.98

41

60,000

65

3,400

1.85

6,290

LED

60

0.98

61

60,000

65

5,100

1.85

9,435

LED

80

0.98

82

60,000

65

6,800

1.85

12,580

LED

100

0.98

102

60,000

65

8,500

1.85

15,725

LED

120

0.98

122

60,000

65

10,200

1.85

18,870

LED

150

0.98

153

60,000

65

12,750

1.85

23,588

LED

200

0.98

204

60,000

65

17,000

1.85

31,450

Light source at a glance

Highlights of Induction Lamps:

  • Long lifespan due to the absence of electrodes (filaments).
  • Very high energy conversion efficiency of between 62 and 90 Lumens/Watt [higher power lamps are more energy efficient].
  • High power factor (>0.98).
  • Very low "ballast overhead" of the high frequency electronic ballasts which are typically between 95% to 98% efficient.
  • Minimal Lumen depreciation (declining light output with age) compared to other lamp types as filament evaporation and depletion is absent.
  • "Instant-on" and "hot re-strike", unlike most HID lamps used in commercial-industrial lighting applications (such as mercury-vapour lamp, sodium-vapour lamp and metal halide lamp).
  • Environmentally friendly as induction lamps use less energy, and use less mercury per hour of operation than conventional lighting due to their long lifespan. The mercury is in a solid form and can be easily recovered if the lamp is broken, or for recycling at end-of-life.

KIL ELECTRONIC BALLAST

Common Ballast Specifications:-

Input Voltage140VAC-280VAC
Case Temp.<65°C
Input Frequency45 to 60Hz
Operating Temp.(Open Fixture) & (Closed Fixture) 0°C to 60°C & -20°C to 60°C
Output Frequency220KHz ± 5%
Power Factor > 0.96
THD < 10%
Input current Crest factor < 1.6
Constant Wattage Output± 10%

Input Current ratings:

Wattage (watts)

40

60

80

100

120

200

Input Current (amperes)

0.32-0.16

0.58-0.21

0.68-0.28

0.86-0.36

1.02-0.43

1.72-0.73