What will affect the life of switching power supply

The life of the switching power supply mainly depends on the electrolyte. As the temperature rises, the electrolyte vaporizes and leaks through the sealing part of the capacitor, and the internal electrolyte continues to decrease. As the number of the electrolyte decreases, tanδ will gradually increase. As a result, the heat generated when the pulse current passes through increases, which further reduces the life of the switching power supply. However, many factors affect the life of the switching power supply. Let us introduce in detail the factors that affect the life of the switching power supply. You can understand the factors that affect the life of the DR-Din rail power supply by understanding the factors that affect the life of the switching power supply.

Here is the content list:

• Switching power supply fan

• Optocoupler

• Switch times

• Thermistor power resistors

Switching power supply fan

The life of the switching power supply fan is affected by the degree of wear of the bearings and spherical bearings. The bearing part generates heat due to rotation. Although the fan itself can cool down to a certain degree, it cannot fundamentally solve the heat generation problem. Measure the heating value of the bearing part, the smaller the heating value, the better the quality, so to choose the appropriate switching power supply. The lubricating oil in the bearing part and the wear of the bearing cause the number of revolutions to decrease, increase the noise, and accelerate the end of life. Regarding the reduction of the number of revolutions, the standards of each manufacturer are different, but generally, the upper limit is 3 to 5% of the initial value. The life span is shortened as the temperature rises.

Optocoupler

The current transmission rate will gradually decrease over time. As a result, the current of the light-emitting diode will continue to increase, sometimes reaching the maximum limit current, causing the switching power supply system to run out of control.

Switch times

Most switching power supplies are equipped with a capacitor input rectifier circuit. When the power is connected, a surge current will be generated, which will cause the contact fatigue of the switching power supply, and cause problems such as increased contact resistance and adsorption. Theoretically, during the expected life of the power supply, the number of on-off times of the switch is about 5,000 times.

Thermistor power resistors

To resist the inrush current generated when the power is turned on, the designer uses resistors in parallel with SCR and other components. When the switching power supply is turned on, the power peak value is as high as tens to hundreds of times the rated value, which results in thermal fatigue of the resistor and causes an open circuit. Under the same conditions, thermistor power resistors will also experience thermal fatigue.

The most important thing for switching power supplies to pay attention to is the contact arc phenomenon caused by the surge voltage of the power load and the contact problem caused by the inrush current. Generally speaking, the greater the switching voltage and current, the shorter the contact life. The lower the power factor, the shorter the life. You can also judge the life of the DR-Din rail power supply through these factors.

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