OliNo executes endurance tests on (led)lamps. This article explaines what the data that is obtained when doing endurance tests on (led)lamps. An ASSIST publication was used as the basis for the derivation of the results of the measurements.

First the test setup is explained and then the measurements done and extracted.

The endurance test setup

The lamps are mounted on a big support plate, together with a set of other lamps.

The support plate with the lamps all in endurance test

Visible in red is a data logger, of brand and type Hobo U12-011; this logs evert 10 minutes the ambient temperature (T) and relative humidity (RH).

The plate is mounted in horizontal position and this way the lamps have their endurance test.

The normal position in which the lamps undergo their endurance test

The lamps burn 23 hours per day and are switched off 1 hour per day. This happens with help of an automatic timer switch. Also available is an hour counter counting the amount of on-hours.

Left the over voltage protection and the timing switch, and right the hour counter

Also available is an over voltage protection.

The lamp data derived from the endurance test

The remainder of the explanation is about the lamp in endurance test. We will take a non-existent example lamp, called Example.

Start date

This Example went into test on 5 Jan 2009 and every day 23 hours of on-time are added.

The ambient temperature T and relative humidity RH

An impression of the T and RH that this lamp has seen is given herewith. This overview is(approximately) adapted to the time period during which the lamp was under test.

T and RH seen by the lamp

T varied between 10 and 20 deg C and RH varied between 20 and 45 %.

Data of the repetitive measurements done on the Example

#hours	Iv [Cd]	CCT [K]	P [W]	PF [-]	CRI [-]	Tamb [ºC]
0	500	4022	15.0	0.85	82	22.9
1000	515	4025	15.0	0.84	82	23.4
1650	510	4022	15.1	0.85	81	23.8
2080	500	4001	15.0	0.85	80	23.3
2613	480	3980	14.9	0.85	80	23.0
3340	460	3975	15.0	0.85	79	23.5
4012	450	3970	15	0.85	78	22.8
4852	440	3969	15.1	0.85	78	23.6
5520	432	3969	15.0	0.84	77	24.0
6015	426	3969	15.1	0.83	75	23.2

T_amb is the ambient temperature for every measurement that was done on this Example. The Example was always stable in temperature before the measurements were carried out. The values are relatively close to each other and should not have a (big) effect on the other measurement results.

Variation in parameter values compared to 100 % value at 1000 hours.

The intensity increases until 1000 hours and then decreases. In the burning period from 4000-6000 the decrease is less fast than between 1000-4000.

The time that it takes the intensity to go down to 70 % of the initial value can be found by doing an exponential extrapolation of the measurement data form 1000 hours onwards (see also the ASSIST publication).

Change in intensity extrapolating the decrease after 1000 burn hours

The extrapolation shows the L70 level (70 % of the level at 1000 hours) of the intensity os reached after about 10,000 hours.

Chromaticity values

The variation in chromaticity indicates the change in color.

#hours	x	y
0	0.3800	0.3765
1000	0.3805	0.3771
1650	0.3815	0.3772
2080	0.3825	0.3777
2613	0.3826	0.3773
3340	0.3827	0.3779
4012	0.3840	0.3780
4852	0.3835	0.3788
5520	0.3827	0.3782
6015	0.3825	0.3785

Change in color during the endurance test

This graph shows the color points for the colors measured during specific moments in the endurance test. The color coordinates at 1000 burn hours are taken as the reference values. Around these coordinates a 4 step MacAdams ellips is drawn. When color coordinates go outside this ellips then there is a high probability that observers will notice this a a color difference.

For the Example the colors remain within the 4-step MacAdams ellips.

More information

When you are interested in having endurance tests done on your lamps, please see the services page.