Overload test - the problem you have neglected in power supply testing (3)

As a power supply device for electronic products or batteries, the power supply must not only meet the requirements of the power supply product, but also have its own protection measures, such as overvoltage, overcurrent, and overtemperature protection. This article takes the overcurrent protection of the constant voltage source as an example to introduce.

First of all, for overcurrent protection, not only the overcurrent protection point should be tested , but also the overcurrent protection time and protection stability should be tested.

Overcurrent protection point test, also known as OCP (over current protection) test. There are three types according to the protection mode: current convergence or even cut-off, constant current, and current increase. If the more complicated high-power power supply system is divided into multiple stages, it will not be discussed here. For protection mode 1, the OCP point is generally 110% to 130% of the rated value.

In the past, the current was adjusted manually and the phenomenon was observed manually. However, factors such as the reaction speed of the hands and eyes required multiple measurements to determine the result. The Faith load machine itself has an OCP function.

There are two types of OCP functions for Feisi loads: step-by-step (FT6300/FT6800) and split-step (FT66100).

The stepping type (FT6300/FT6800) can set the starting current, step current, step time, and trigger voltage (voltage drop). The load will automatically scan and stop according to the settings, and record the maximum current point of the test results and the maximum power point of the entire test.

Step-by-step (FT6800), you can set the starting current, ending current, number of steps, trigger voltage. You can also set the upper and lower limits for easy production debugging. The load will automatically scan the test. Of course, you can also test with the load software. The load software not only supports OCP, but also supports OVP/OPP testing, and can perform U/I curve scanning.

Overcurrent protection time test: Use the pulse mode of the Feisi load dynamic mode to test the protection time of the power supply or battery. The time resolution is 1uS. If you do not want to use the pulse mode, you can also use the continuous mode for testing, but it is not as easy to use as the pulse mode.

The protection stability test is of course carried out in conjunction with the software using the dynamic mode or sequence mode of the software. The dynamic mode is shown above, and the sequence mode is shown below.

Production line test overcurrent protection: Production line test overcurrent protection is not so troublesome. Use the automatic test function of Feisi load to divide the overcurrent protection into two steps: the lower limit value, the power supply does not protect, and the upper limit value, the power supply must protect. This logical judgment is sufficient.