Analysis and discussion on ultra-low temperature test of LED street lamps and floodlights

Whether LED outdoor lamps, especially LED street lamps and outdoor LED floodlights can work properly in cold environments is one of the quality issues that buyers need to consider. The author conducted this test using a 120W LED street lamp and an 80W LED floodlight as samples to verify the working condition of LED lamps in low temperature environments.

Test purpose: 1. To evaluate whether the lamp can work in a low temperature environment; 2. To evaluate the degree of damage to the lamp components caused by the low temperature environment and whether it can work after the stress is eliminated.

Test samples: 1. External power supply, 4*30W COB light source street lamp 1; 2. External power supply, 4*20W COB light source floodlight 1;

Standard: Refer to IEC60086-2-1 2007 Part 2-1EssaiA standard

Condition selection: Four temperatures (-20 ℃ , -25 ℃ , -35 ℃ , -40 ℃ ) were selected for evaluation, and the test time was 4 hours in total (2h+0.5h*4).

Test equipment: High and low temperature exchange temperature test chamber (Guangzhou Gongwen Testing Equipment Co., Ltd.)

Sample processing method: Place the power supply of the two lamps in the test box, connect the lamp plug to the outside power supply through the hole in the test box, and seal the hole with a rubber plug.

Testing process:

1. The lamp can be lit at room temperature and work normally.

2. Place the lamp in a test chamber and run it at -20℃ for 2 hours to see if it can light up normally .

3. Adjust the temperature to -25 ℃ and run for 0.5 hours to see if the lamp can light up normally .

4. Adjust the temperature to -35 ℃ and run for 0.5 hours to see if the lamp can light up normally .

5. Adjust the temperature to -40 ℃ and run for 0.5 hours to see if the lamp can light up normally .

6. Adjust the temperature to -35 ℃ and run for 0.5 hours to see if the lamp can light up normally.

Test results:

Both lamps can light up normally at room temperature, -20 ℃, -25 ℃ and -35 ℃ ; when the temperature drops to -40 ℃ , both lamps cannot light up; when adjusted back to -35 ℃ , both lamps light up again.

Test conclusion: The lowest temperature that these two LED lamps can withstand is -33 ℃ , but not -40 ℃ . (Note: The preferred temperatures listed in the IEC60086-2-1 standard are -40 ℃ , -33 ℃ , -25 ℃ , and -20 ℃ . Although the actual test temperature is -35 ℃ , the judgment result is -33 ℃ .)
 

Analysis and discussion:

At present, domestic lighting testing laboratories mainly focus on safety and EMC testing of LED lamps, and rarely involve environmental testing and reliability testing of LED lamps. The testing basis is only based on industry experience, and there is no corresponding testing specification or standard.

The main difficulties faced in this experiment are:

1. There are only 2 test samples (5 or more samples are preferred), and the test results are accidental;

2. The test time is short, only 4 hours (actually you can choose 16 hours, 72 hours, 96 hours or longer), and it is impossible to verify the changes that occur over a longer period of time;

3. Few references. Special thanks to the authors of the article "Analysis of the Impact of Low Temperature Environment on LED Lighting Devices", Wang Lei and Wei Dao from the Xinjiang Uygur Autonomous Region Product Quality Supervision and Inspection Institute.

Attached test photos: