Some Good Practices in Lighting

• High pressure sodium vapour (HPSV) lamps offer more efficacy. But the colour rendering property of HPSV is very low. 
• Hence, it is recommended to install HPSV lamps for applications such as street lighting, yard lighting etc. 

Installation of LED panel indicator lamps in place of filament lamps :

Panel indicator lamps are used widely in industries for monitoring fault indication, signaling etc. Conventionally, filament lamps are used for the purpose, which has got the following disadvantages :  

• High energy consumption (15 W/lamp). 
• Failure of lamps is high (Operating life less than 1,000 hours). 
• Very sensitive to the voltage fluctuations. Recently, the conventional filament lamps are being replaced with Light Emitting Diodes (LEDs). 

The LEDs have the following merits over the filament lamps.

• Lesser power consumption (Less than 1 W/lamp). 
• Withstand high voltage fluctuation in the power supply.
• Longer operating life (more than 1,00,000 hours). 

It is recommended to install LEDs for panel indicator lamps at the design stage.

Light Distribution :

• Energy efficiency cannot be obtained by mere selection of more efficient lamps alone. Efficient luminaires along with the lamp of high efficacy achieve the optimum efficiency.
• Mirror-optic luminaires with a high output ratio and bat-wing light distribution can save energy. 
• For achieving better efficiency, luminaires that are having light distribution characteristics appropriate for the task interior should be selected. The luminaires fitted with a lamp should ensure that discomfort glare and veiling reflections are minimised.
• Installation of suitable luminaires, depends upon the height-Low, Medium and High bay. Luminaires for high intensity discharge lamp are classified as follows :

1. Low bay, for heights less than 5 metres. 
2. Medium bay, for heights between 5-7 metres.
3. High bay, for heights greater than 7 metres. 

• System layout and fixing of the luminaires play a major role in achieving energy efficiency. 
• This also varies from application to application.
• Hence, fixing the luminaires at optimum height and usage of mirror optic luminaires leads to energy efficiency.

 Light Control :

• The simplest and the most widely used form of controlling a lighting installation is on-off switch. The Initial investment for this set up is extremely low, but the resulting operational costs may be high. This does not provide the flexibility to control the lighting , where it is not required.
• Hence a flexible lighting system has to be provided which will offer switch-off or reduction in lighting level when not needed. The following light control systems can be adopted at design stage 

Grouping of lighting system to provide greater flexibility in lighting control :

• Grouping of lighting system, which can be controlled manually or by timer control.

Installation of microprocessor based controllers :

• Another modern method is usage of microprocessor / infrared controlled dimming or switching circuits. 
• The lighting control can be obtained by using logic units located in the ceiling, which can take pre-programme commands and activate specified lighting circuits.
• Advanced lighting control system uses movement detectors or lighting sensors to feed signals to the controllers 

Optimum usage of daylighting :

• Whenever the orientation of a building permits day lighting can be used in combination with electric lighting.
• This should not introduce glare or a severe imbalance of brightness in visual environment,
• Usage of day lighting (in offices/air conditioned halls) will have to be very limited, because the air conditioning load will increase on account of the increased solar heat dissipation into the area.
• In many cases, a switching method to enable reduction of electric light in the window zones during certain hours, has to be designed. 

Installation of “exclusive” transformer for lighting :

• In most of the industries, lighting load varies between 2 to 10%. Most of the problems faced by the lighting equipment and the “gears” is due to the voltage fluctuations. 
• Hence, the lighting equipment has to be isolated from the power feeders. This provides a better voltage regulation for the lighting.
• This will reduce the voltage related problems, which in turn increases the efficiency of the lighting system.

 Installation of servo stabilizer for lighting feeder :

• Wherever, installation of exclusive transformer for lighting is not economically attractive, servo stabilizer can be installed for the lighting feeders.
• This will provide stabilized voltage for the lighting equipment. The performance of “gears” such as chokes ballasts, will also improved due to the stabilized voltage.
• This set up also provides, the option to optimise the voltage level fed to the lighting feeder. In many plants during the non-peaking hours, the voltage levels are on the higher side.
• During this period, voltage can be optimised, without any significant drop in the illumination level.

Installation of high frequency (HF) electronic ballasts in place of conventional ballasts :

New high frequency ( 28-32 kHz ) electronic ballasts have the following advantages over the traditional magnetic ballasts.

• Energy savings up to 35%
• Less heat dissipation, which reduces the air conditioning load
• Lights instantly
• Improved power factor
• Operates in low voltage load
• Less in weight
• Increases the life of lamp
• The advantage of HF electronic ballasts, out weigh the initial investment (higher costs when compared with conventional ballast).
• In the past the failure rate of electronic ballast in Indian industries was high.
• Recently , many manufacturers have improved the design of the ballast leading to drastic improvement in their reliability.
• The life of the electronic ballast is high especially when used in a lighting circuit fitted with a automatic voltage stabilizer.
• Table 1 gives the type of luminaire, gear and controls used in different areas of industry.

Location	Source	Luminaire	Gear	Controls
Plant	HID/FTL	Industrial rail Reflector High bay medium bay Low bay	Conventional / low loss Electronic ballast	Manual/electronic
Office	FTL/CFL	FTL/CFL	Electronic/low loss	Manual/auto
Yard	HID	Flood light	Suitable	Manual
Road peripheral	HID/PL	Street light luminaire	Suitable	Manual