About the resistor application 5 points
Resistor hot design problem
The resistor is installed in the installation of heat dissipation problems: large power resistors should be mounted on the metal base to dissipate; not in the case where there is no radiator, put the power resistor directly on the terminal or printed board. The power resistor is installed at a horizontal position as possible; the length of the lead is short, so that the contacts of the printed circuit board can be dissipated, but it can’t be too short, and it is better to be bent to allow thermal expansion, such as With the mounting frame, it is necessary to consider the stress of the thermal expansion and shrinkage; when the resistor is in a row or a row, consider the influence of ventilation and the effects of mutual heat dissipation, and appropriately combined; need to be considered when needed The heat dissipation caused by it.
Resistor drop application
For fixed resistors or potentiometers, important factors affecting reliability are voltage, power and ambient temperature; for thermistors, mainly power and ambient temperature. Therefore, the above parameters should be applied separately.
Resistor anti-static
Metal membrane resistors having a small tolerance (such as 0.1%) are susceptible to electrostatic damage. A thin film resistance having a small size, high resistivity, removing significant changes in the resistance (generally smaller), and the temperature coefficient is also correspondingly varied.
Resistor pulse peak voltage
Even if the average power does not exceed the rated value, the pulse peak voltage and peak power is not allowed to be too high.
The peak voltage of the synthetic resistor does not exceed 2 times that of the rated voltage, the peak power is not above 30 times; the peak voltage of the thin film resistor does not exceed 1.4 times the rated voltage, the peak power does not exceed the rated power; the wire wind resistor can be subject to ratio Usually the operating voltage is much more pulse, but the corresponding defect is also applied in use.
Resistor aid insulation
When the potential difference between the resistance or potentiometer and the ground is more than 250V, auxiliary insulation measures are needed to prevent the instructions.