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The parameters of the varistor and the detection method-Huagu Electronics.

Release time:

2024-03-07

Many people have already known about varistors: varistors are voltage-limiting protection devices. Using the nonlinear characteristics of the varistor, when the over-voltage appears between the two poles of the varistor, the varistor can clamp the voltage to a relatively fixed voltage value, so as to realize the protection of the post-stage circuit. So, what are the parameters and detection methods of the varistor?

Varistor parameters are these:

1. Maximum limit voltage (V): refers to the maximum voltage value that can be borne by both ends of the varistor.

Static capacitance (PF): refers to the inherent capacitance of the varistor itself.

3. Nominal voltage (V): refers to the voltage value across the varistor when 1mA DC current is passed.

4. Residual voltage ratio: When the current through the varistor is a certain value, the voltage generated at both ends of it is called the residual voltage of this current value. The residual voltage ratio is the ratio of the residual voltage to the nominal voltage.

5. Leakage current (mA): Leakage current, also known as waiting current, refers to the current flowing through the varistor at the specified temperature and maximum DC voltage.

6. Flow capacity (kA): Flow capacity, also known as flow capacity, refers to the maximum pulse (peak) current value allowed through the varistor under specified conditions (specified time interval and number of times, applying standard impulse current).

7. Insulation resistance: refers to the resistance value between the lead wire (pin) of the varistor and the insulating surface of the resistor body.

8. Current temperature coefficient: refers to the relative change of the current flowing through the varistor when the voltage at both ends of the varistor remains constant and the temperature changes by 1 ℃.

9. Voltage nonlinear coefficient: refers to the ratio of the static resistance value to the dynamic resistance value of the varistor under the action of a given applied voltage.

10. Voltage temperature coefficient: refers to the rate of change of the nominal voltage of the varistor within the specified temperature range (temperature is 20 ℃ ~ 70 ℃), that is, when the current through the varistor remains constant, the temperature changes by 1 ℃, The relative change of the voltage across the varistor.

11. Voltage ratio: refers to the ratio of the voltage value generated when the current of the varistor is 1mA to the voltage value generated when the current of the varistor is 0.1mA.

detection method of varistor:

Varistors are generally used in parallel in the circuit. When the voltage across the resistor changes and exceeds the rated value, the internal resistance of the resistor decreases sharply, presenting a short-circuit state, and the current fuse connected in series on the circuit is blown to protect it. Varistor in the circuit, often used for power supply overvoltage protection and voltage regulator.

With varistor three parameter tester, can measure the varistor voltage, leakage current, linear coefficient.

In the case of amateur work, the multimeter is set to 10k gear during measurement, and the stylus is connected to both ends of the resistor. The multimeter should display the resistance value marked on the varistor. If the deviation from this value is large, the varistor is damaged.

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