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10 Problems that Can Cause Led Driver Failure (Part 2)

Mar. 17, 2020


3. Do not understand the working characteristics of LED

Once a customer required the lamp input power to be a fixed value, fixed 5% error, only for each lamp to adjust the output current to reach the specified power. As a result of different working environment temperature, and lighting time is different, the power of each lamp still can have big difference.

The customer makes such a request, despite its marketing and business considerations. However, the volt-ampoule characteristic of LED determines that the LED driver is a constant current source, and its output voltage varies with the LED load series voltage Vo. Under the condition that the overall efficiency of the driver is basically unchanged, its input power varies with Vo.

At the same time, the overall efficiency of ETL LED driver will increase after the heat balance. Under the same output power, the input power will decrease compared with the starting time.

Therefore, the indoor LED driver application in the formulation of requirements, should first understand the working characteristics of the LED, to avoid putting forward some indicators that do not conform to the principle of working characteristics, and to avoid the occurrence of indicators far beyond the actual demand, to avoid quality surplus and cost waste.

4. Failure in test

There have been many brands of LED drives purchased by customers, but all the samples failed during testing. Later, after on-site analysis, it was found that the customer used the self-coupling voltage regulator to directly supply power to the LED driver for testing, and gradually increased the voltage regulator from 0Vac to the rated operating voltage of the LED driver after power on.

Such a test operation makes it easy for the LED driver to start and work with load when the input voltage is very small, which will cause the input current to be much higher than the rated value, and the internal input terminal related devices, such as fuse, rectifier bridge, thermistor, etc., will fail due to excessive current or overheating, resulting in the driver failure.

Junction Box Led Driver

Junction Box Led Driver

Therefore, the correct test method is to adjust the voltage regulator to the rated operating voltage range of Junction box LED driver, and then connect the driver to power test.

Of course, technically improved design can also avoid the failure problem caused by such test misoperation: setting up the starting voltage limit circuit at the driver input and the input undervoltage protection circuit.When the input does not reach the starting voltage set by the driver, the driver does not work;When the input voltage is reduced to the input undervoltage protection point, the driver enters protection.

Therefore, even if the customer test process is still using the operating steps of the self-coupling voltage regulator, the driver has a self-protection function without failure.However, customers should carefully check whether the purchased LED drive products have this protection before testing (considering the actual application environment of LED drives, most LED drives do not have this protection).