Calculation of the Maintenance Factor for Cariboni Lite ... · for street lighting and residential lighting . ... THE CALCULATION OF THE MAINTENANCE FACTOR ... in the norm IESNA RP-8-00

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Calculation of the

Maintenance Factor for Cariboni Lite & Fivep Lite

LED products for street lighting

and residential lighting


INDEX

1. PREAMBLE 3 2. FORMULA FOR THE CALCULATION OF THE MAINTENANCE FACTOR 4 3. DEFINITION OF THE LLMF VALUE (Lamp Lumen Maintenance Factor) 5 4. DEFINITION OF THE LSF VALUE (Lamp Survival Factor) 7 5. DEFINITION OF THE LMF VALUE (Luminaire maintenance Factor) 9 6. CALCULATION OF THE MAINTENANCE FACTOR FOR FIVEP PRODUCT 10 7. CONCLUSIONS 15


1. PREAMBLE

A correct definition of the maintenance factor which must be used in the lighting calculations with LED products is becoming more and more important in a lighting world where the continuous research in the field of new sources and new optical systems in order to achieve bigger energy savings, granting in any case the compliance with the norms (i.e. EN 13201), is leading to continuous innovation. The maintenance factor depends mainly on: Protection degree of the fitting: a watertight product (IP65 or higher), for instance, will have a higher maintenance factor than a

fitting with a low protection against penetration of water and dust (IP23 or similar), since its tightness prevents it from penetration of dirt/soil in the optical compartment.

Type of light source: a fitting whose light source are LEDs or fluorescent lamps will have a higher maintenance factor than one with high intensity discharge lamps, thanks to the lower temperatures on the closure screens of the fittings and therefore thanks to lower possibilities of adhesion of dust and dirt to the closure screen due to temperature.

Type of installation: a fitting for street or residential lighting, which is normally installed downwards, with a glass surface parallel to

the road, should have a higher maintenance factor than a fitting for other installation/use, especially in those cases where the glass of the fitting is directed upwards and therefore exposed to possible contaminations (i.e. recessed fittings, floodlights).

Frequency of the maintenance operations: another factor which influences the calculation of the maintenance factor for lighting

fittings is the cleaning interval of the fitting. As far as conventional lighting fittings are concerned, the need to replace the lamp approximately each two years led to frequent cleaning intervals, since the cleaning of the closure screen of a fitting was mainly carried out during the same intervention when the lamp was replaced. The use of LED sources cancels the need of periodically replacement of the light source, but this does not mean that the cleaning procedure must be cancelled as well; a periodical maintenance for the cleaning of the closure screens must be foreseen also for LED products, in order to maintain them in the best possible conditions, as far as their efficiency is concerned. The cleaning interval must be determined according to the environmental conditions and determined case by case.


2. FORMULA FOR THE CALCULATION OF THE MAINTENANCE FACTOR

The method which Fivep is adopting in order to define the general maintenance factor for the lighting calculations with LED products for street lighting and residential/urban lighting is the one included in the norm IESNA RP-8-00 dtd. 2005 and in the norm CIE 154:2003, which connects all the factors listed in the preamble in a single formula:

MF = LLMF x LSF x LMF Where:

MF = Maintenance factor LLMF = Lamp Lumen Maintenance Factor

It represents the reduction of the flux of the LEDs during the lifetime of the fitting and it is expressed as a coefficient which represents the ratio between the initial lumen output and the remaining lumen output at the end of a certain period which is meant as lifetime of the LEDs; these data are given by the LEDs manufacturers.

LSF = Lamp Survival Factor It represents the percentage of the surviving LEDs after a certain period starting from the installation date; this data is given by the LEDs manufacturers.

LMF = Luminaire Maintenance Factor It represents in particular the influence of the external factors on the fitting and it is strongly connected with the environment the fitting is installed in. It is expressed as a coefficient representing the ratio between the initial lumen output and the remaining lumen output after a certain period, to be defined according to the clearing intervals. This coefficient is based on IESNA standard tables and we normally refer to “very clean” environments.


3. DEFINITION OF THE LLMF VALUE (Lamp Lumen Maintenance Factor)

This value depends exclusively on the type of LED source in use and on the conditions the LEDs are operating at. In fact, the ability to maintain the highest possible remaining percentage of the initial lumen output of the LEDs during the lifetime of the fitting depends on the conditions the LEDs are operating at and on the features of each fitting in terms of thermal management. Fivep asked the main LED suppliers, Cree and Lumileds, to prepare some tests concerning the lifetime of the LEDs according to the TM-21 method, in order to define univocal values for the definition of the lifetime and lumen maintenance of the LEDs, useful also for the comparison with other suppliers using the same method. As an example, we are showing in the following pages the tests carried out by our supplier CREE on the LED series XP-G and XP-G2, that we are using or that we are going to use in our fixtures. Remarks:

- The TM-21 method connects the timing (in hours) of the laboratory tests to a multiplier by 6, in order to define the lifetime of the LEDs at a predefined lighting performance (L70 = 70% of the initial lumen output). The increasing of the test time will increase the limit hours to reach the L70 value; nowadays projections on lumen maintenance are limited to 51.400h for CREE XP-G2 LEDs and to 60.500h for Lumileds LUXEON-M LEDs. In the next months, thanks to the increasing of the duration of the tests, these values may be increased.

- We refer to CREE tests at 700mA/105°C temperature on the LEDs and to LUMILEDS tests at 700mA/105°C temperature on the LEDs


TM-21 – CREE XP-G2 LEDs

As far as the CREE XP-G LEDs are concerned, the remaining lumen output at 51.400h is 94%. The LLMF for Fivep products equipped with XP-G2 LEDs can be set to 0,94.

TM-21 – LUMILEDs LUXEON-M LEDs

As far as the LUMILEDs LUXEON-M LEDs are concerned, the remaining lumen output at 60.000h is 100%. The LLMF for Fivep products equipped with LUMILEDs LUXEON-M LEDs can be set to 1,00.


4. DEFINITION OF THE LSF VALUE (Lamp Survival Factor)

Also in this case, the value depends on the type of LED source in use and on the thermal management of the entire lighting fitting. In fact, the calculation provided by the LEDs manufacturers in order to define the Lamp Survival Factor are determined according to the power supply current, the Junction Temperature (Tj) on the LEDs and the Surface Temperature on the LEDs (Tsp). In order to define the LSF, Fivep refers to the tests which have been carried out on the whole range of LED products for street and residential/urban lighting and chooses the worst and most critical case in order to define the death rate of the LEDs. The tables shown in the following page show the failure rates of the CREE XP-G2 LEDs and of the LUMILEDS LUXEON-M LEDs.


FAILURE RATE – CREE XP-G2 LEDs

As far as the CREE XP-G2 LEDs are concerned, the surviving LEDs at 51.400h is 100 – 0,159 = 99,841%. The LSF for Fivep products equipped with CREE XP-G2 LEDs can be set to 0,99841.

FAILURE RATE – LUMILEDs LUXEON-M LEDs As far as the LUMILEDs LUXEON-M LEDs are concerned, the surviving LEDs at 60.500h is 100 – 0,001 = 99,999%. The LSF for Fivep products equipped with LUMILEDs LUXEON-M LEDs can be set to 0,9999.


5. DEFINITION OF THE LMF VALUE (Luminaire Maintenance Factor) As explained, this value is not depending on the LEDs; on the contrary, it is directly connected with the type of lighting fitting, its installation environment and the cleaning intervals foreseen in the installation. Considering that our fittings are all IP65 or IP66, according to the Luminaire Dirt Depreciation table contained in the IESNA RP-8-00 dtd. 2005 norm, we can make the following hypothesis about the possible scenarios:

- Very clean environment (low ambient contamination level, light traffic – residential areas) and clearing interval of 2 years. In this case, the LMF can be set to 0,96;

- Clean environment (moderate contamination level, moderate to heavy traffic) and cleaning interval of 4 years. In this case, the LMF can be set to 0,89.


6. CALCULATION OF THE MAINTENANCE FACTOR FOR FIVEP PRODUCTS By applying the above mentioned considerations to our product range, we obtain the maintenance factors listed in the following table:

PRODUCT LLMF LSF LMF

Very clean environment + 2 years cleaning

interval

LMF Clean environment +

4 years cleaning interval

MAINTENANCE FACTOR

Very clean environment + 2 years cleaning interval

MAINTENANCE FACTOR

Clean environment + 4 years cleaning interval

KAI SMALL

0,94 0,9984 0,96 0,89 0,90 0,84

KAI MEDIUM

0,94 0,9984 0,96 0,89 0,90 0,84




interval



MAINTENANCE FACTOR


MAINTENANCE FACTOR


KALOS

0,94 0,9984 0,96 0,89 0,90 0,84

LEVANTE SMALL

0,94 0,9984 0,96 0,89 0,90 0,84

LEVANTE MEDIUM

0,94 0,9984 0,96 0,89 0,90 0,84




interval



MAINTENANCE FACTOR


MAINTENANCE FACTOR


PHOS

0,94 0,9984 0,96 0,89 0,90 0,84

LINK (FLAT LINK, SOFT LINK, BIG LINK)

0,94 0,9984 0,96 0,89 0,90 0,84

YPSILON

0,94 0,9984 0,96 0,89 0,90 0,84




interval



MAINTENANCE FACTOR


MAINTENANCE FACTOR


FLYER

0,94 0,9984 0,96 0,89 0,90 0,84

CLASSIC

0,94 0,9984 0,96 0,89 0,90 0,84

SEVEN & CIRCLE

0,94 0,9984 0,96 0,89 0,90 0,84




interval



MAINTENANCE FACTOR


MAINTENANCE FACTOR


BRICK & QUADRA

0,94 0,9984 0,96 0,89 0,90 0,84

NEWTON

1,00 0,999 0,96 0,89 0,96 0,89


7. CONCLUSIONS Based on the above explained criteria, the definition of the right maintenance factor for each lighting calculation is up to the planner, who will be able to choose the right maintenance factor according to the environmental information and to the cleaning intervals, which must be provided by the customer when requesting a project. The maintenance factor can therefore be customised, according to the information provided by the customer. In its lighting calculations, Cariboni Group uses as a standard the maintenance factor resulting by the formula based on 2 years maintenance cycles. An important remark: Cariboni Group's products for street lighting and residential/urban lighting are available, on demand, with several possibilities of management of the flux/power. The equipment with Philips Xitanium programmable drivers (System 2 on our literature) enables the CLO function (Constant Lumen Output). By means of this possibility, we can adjust the power of the fitting during its lifetime and, in this way, compensate the output degradation of the LEDs. Thanks to this possibility, the LLMF can be set to 1,00 and therefore the maintenance factors will be higher. In case the customer wishes the equipment of the fittings with Philips programmable driver and the use of the CLO function, this can be taken in consideration during the lighting calculation and the Maintenance Factor will be adjusted accordingly.

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Calculation of the Maintenance Factor for Cariboni Lite ... · for street lighting and residential lighting . ... THE CALCULATION OF THE MAINTENANCE FACTOR ... in the norm IESNA RP-8-00