Star Rating of CFL in Sri Lanka

The Compact Florescent Lamps (CFL) are widely used in the world as well as in Sri Lanka for domestic, commercial and industrial lighting. They are considered as energy savers over the conventional incandescent lamps yet it is questionable whether CFLs produced by different manufacturers which has diverse market prices meet the same quality, output of light and energy saving. Therefore, choosing a cheap, energy efficient CFL which will emit required amount of light had been a tough task for the consumers.

The Star Rating of CFL is introduced and regulated by the government to avoid this complexity faced by the consumers in buying CFLs. The Star Rating basically eases the consumers compare CFLs from different manufacturers having different prices. Principally, more the number of stars better the product that you are buying. This article seizes on the important factors measured in obtaining the Star Rating, methodology of calculating the Star Rating and elaborates about the importance, regulations and the standards that are considered in awarding the Star Rating for CFLs.

The testing of CFL to award the Star Rating is carried out in the laboratory of Regional Centre for Lighting (RCL) which was managed by the Sri Lanka Sustainable Energy Authority. This is now under the process of been acquired to the Ceylon Electricity Board (CEB) which is also an affiliated institute of the Ministry of Power and Energy. Before concentrating on the sequence of the test, it is important to be familiar with simple jargon used. The phrase lumen output refers to the light emitted by the lamp in all directions. Efficacy is the proportion of total lumen output of the lamp to the total power input in watt. Integrating Sphere is an equipment used in the laboratory to test the lamp.

There are few aspects that are concerned before awarding the star rating. If these specifications are not met, the lamp will not be awarded with the certificate. The performance test carried out in the RCL is according to SLS 1231:2002.

They are,

• The wattage of the lamp when tested should be less than 115% of its rated wattage.
• The lumen output of the lamp when tested should be 90% of the rated lumen output.
• The 3rd and 5th harmonic currents should not be greater than 86% and 61%
• respectively of the fundamental current.
• The power factor should be greater than 0.5
• Standard Deviation of Colour Matching (STDCM) should be within the range 0 - 5.

Before testing the lamp in the integrating sphere, each CFL lamp is kept turned on for 100 hours continuously. This is called “ageing”. Aged lamp is fixed to the sphere in the same burning position as it was during ageing and kept turned on for 15 minutes before the test. Then the test begins. The lumen output, colour temperature and STDCM are directly calculated using the lab equipments (Integrating Sphere and the LabSphere software). The wattage, current harmonics and power factor are calculated by the power analyser.

    Using the above test results RCL awards the star rating according to the SLS 1225:2002 standard as follows.

Equation 1: Calculation of efficiency

Equation 2: Performance grading calculation

Table 1: Color correction coefficient

Table 2: Star rating

The lumen output, colour temperature, power factor and wattage are measured using the laboratory equipments as mentioned above. Efficacy is calculated according to the Equation 1 and colour correlation coefficient is obtained according to the Table 1 then by substituting the values to Equation 2 the Performance Grading is obtained. As per Table 2 the Star Rating is awarded.

    By analyzing the above criteria mentioned, it is noticeable that efficacy, colour temperature and power factor are vital facts of the Star Rating. This clearly indicates that higher the number of stars better the amount of light emitted for consumed wattages, better the power factor correction and better the colour of the light emitted (the quality of being near to the colour of daylight).  At least one star should be obtained for a CFL in order to be marketed in the local market.

Article By: Supun De Silva

Posted in: Sustainable Energy and Policy