How are varistors tested in air?

1) Measuring tools and materials: Four-and-a-half-digit multimeter: two pieces. A thermostatic oil pan: the size can be customized, but it should not be too small. Precision thermometer. A pair of stainless steel crocodile clips.

2) Measurement method and steps: Fill the thermostatic oil pan with salad oil Put the thermometer horizontally into the oil pan with the scale upward. Swap a pair of alligator clips on a pair of multimeter pen test ends.

Clamp the two lead ends of a standard varistor on the crocodile clip, insert the other end of the multimeter pen into the multimeter, turn on the multimeter and dial it to the appropriate gear for resistance measurement, and the multimeter will show the resistance value of the varistor at room temperature. When the multimeter display value of monitoring oil temperature is relatively stable, it indicates that the oil temperature is relatively stable, and the resistance of the constant temperature in the oil can be tested, such as the resistance value and accuracy of the varistor used for monitoring on the crocodile clip are the same as the resistance accuracy of the varistor to be measured, and the comparison measurement can be carried out.

3) Precautions: The temperature change of the oil in the oil pan should be controlled within the range of 25 3. The two multimeters should be calibrated accurately before measurement, and at least the consistency of the two meters should be checked.

The constant temperature of the varistor to be measured in oil should not be less than 2 minutes, and it should be fully immersed in oil. The temperature probe, the varistor for monitoring, and the resistor to be measured should be placed in the same position in the oil pan to ensure the accuracy of the measurement. Zhixu JEC specializes in manufacturing safety capacitors, varistors, monolithic capacitors, ceramic capacitors, film capacitors, and more quality capacitors in JEC.

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1. Performance characteristicsThe lightning protection element tester is also known as a varistor tester and is suitable for zinc oxide arresters (varistors), cermets.

2. Test of DC parameters of overvoltage protection components such as three-electrode discharge tubes and vacuum lightning arresters.

It has the functions of memory, calculation, maintenance, control and self-test.

It has the functions of high-voltage short-circuit protection, over-current protection, high-voltage setting and so on. The high-pressure self-discharge time is less than 1 second.

The test results are digitally displayed by 3 LCD, with high accuracy and reliability.

Varistor Tester.

2. Technical indicatorsVaristor measurementsDischarge tube measurements3. Other indicatorsInsulation resistance: 6m (500V).

Withstand voltage: AC 50Hz for 1min

Operating Temperature & Humidity: 0 +40 85%RH Storage Temperature & Humidity: -10 +50 90%RH Power Supply: AC220V 10% or DC12V 1000mA Power Consumption: 12W

Dimensions: 208mm(L) 190mm(W) 78mm(D) Weight: 2kg

Lightning Protection Element Tester.

The measuring system of the tester is digital, with good stability and high precision, and the test results are displayed in three and a half digits, and have a memory function, which is intuitive and clear.

> the tester adopts high-frequency and high-voltage technology, and the high-voltage generation, control and measurement are organically combined to form a large closed-loop system to produce high-precision constant current and constant voltage sources. And there are multiple protections, safe and reliable. The entire test process is completed automatically in a matter of seconds by pressing the measurement button.

Manual adjustment measures the leakage current of the specimen at any voltage.

When the varistor is tested for impact, with the increase of the number of impacts to be carried out, the impulse current applied each time should be reduced accordingly, the varistor is measured when the multimeter is placed in 10k gear, the meter pen is connected to both ends of the resistor, the multimeter should show the resistance value marked on the varistor, if it exceeds this value, the varistor **, it means that the varistor has been damaged, the selection of varistor, generally select the nominal varistor voltage V1mA and the current capacity of the two parameters.

A varistor is a component with transient voltage suppression, which can be used to replace the combination of transient suppression diode, Zener diode and capacitor, and the thermistor is different from the thermistor: the thermistor is a current limiting varistor, and the varistor is a voltage limiting effect.

When the voltage is instantly higher than a certain value, the varistor resistance value drops rapidly, and the large current is turned on, so as to protect the IC or electrical equipment, when the voltage is lower than the working voltage value of the varistor, this is the working principle process of the varistor.

Talk about how to test her with a multimeter, someone said, with a multimeter resistance test, as long as the resistance is infinite, it is good, this method is only a rough judgment of him, and it is too inaccurate, you must know that the open circuit is also infinite. So is there a concise and accurate way to judge? The answer is yes, there is!

Here's how: We all know that any electronic component itself has a capacitance, and according to this principle, we can measure it with a digital multimeter capacitance file. Capacity is good, otherwise it is broken! It's bad!

1. Put the multimeter in 10k gear, the meter pen is connected to both ends of the resistor, the multimeter should show the resistance value marked on the varistor, if it exceeds this value very much, it means that the varistor has been damaged.

2. As the voltage applied to the varistor continues to increase, its resistance value can change from m (megaohms) to m (milliohms). When the voltage is low, the varistor works in the leakage current area, showing a large resistance, and the leakage current is very small; When the voltage rises into the nonlinear region, the voltage changes little when the current changes in a considerable range, showing good voltage limiting characteristics. When the voltage rises again, the varistor enters the saturation zone, presenting a very small linear resistance, due to the large current, the varistor will overheat and burn or even explode after a long time.

Varistors"It is a resistive device with nonlinear volt-ampere characteristics, which is mainly used for voltage embedding when the circuit is subjected to overvoltage, and absorbs excess current to protect sensitive devices. The English name is "voltage dependent resistor", abbreviated as "VDR", or "varistor"."。The resistive body material of varistors is semiconductors, so it is a variety of semiconductor resistors.

Massively used"Zinc oxide"(ZNO) varistor, its main material is composed of the divalent element zinc (Zn) and the hexavalent element oxygen (O). So from a material point of view, zinc oxide varistors are a kind of "-oxide semiconductors". In Taiwan, varistors are called"Surge absorber"or "electrical shock (surge) suppressor (absorber)".

Depending on the purpose of use, varistors can be divided into varistors for protection and varistors for circuit functions.

How varistors are measured, and what they actually do in a circuit.

You can use a multimeter to judge the quality of the varistor.

Specific operation: Put the multimeter in 10k gear, the meter pen is connected to both ends of the resistor, the multimeter should show the resistance value marked on the varistor, if it exceeds this value is very large, it means that the varistor has been damaged.

A varistor is a semiconductor device with zinc oxide as the main raw material.

It is also a non-linear sensitive element.

Sensitive protection is only performed under the action of voltage.

When measuring the varistor, first of all, we need to understand the voltage value of the varistor, we can use a suitable voltage source to connect a protection resistor in series to apply voltage to the varistor, measure the voltage value of the varistor, and see if it is on the nominal value, if it can be judged to be good.

If there is a large deviation from the nominal value, there is a problem with the varistor.

The varistor has a resistance value, but we use an ordinary multimeter, which cannot read the number and is displayed as infinity.

So, how to measure the quality of varistor: it can be divided into the following points: 1. Choose professional varistor test instruments for testing.

2. You can use an oscilloscope to test the voltage first: when using the oscilloscope for testing, set the input current to 1madcTest the voltage to see if it is consistent with the nominal voltage of the varistor, if the voltage is low, the varistor is damaged.

The varistor has been short-circuited, if the varistor voltage is too high, or there is no nonlinearity, there is no curve bar, it means that the varistor has been open-circuited.

Leakage current: When testing leakage current, the nominal voltage value of this varistor can be checked in advance, and the test voltage of the oscilloscope can be adjusted to the corresponding voltage range.

If the current tested exceeds 100 microamps, the varistor has a problem, because the leakage current of the varistor will be controlled very small when the varistor is tested at the factory, and generally will not exceed 30 microamperes.

We can only do these two ordinary things, if we have to test other parameters, the oscilloscope has no way to test, then more professional equipment is needed.

3. You can also use a multimeter to test, if the resistance value can be measured, you can basically determine that this varistor is problematic, do not use it.

If you use a varistor that is not up to specification and of poor quality, varistor components** may occur.

or thus affect the use of other components.

Therefore, when the varistor measurement is bad, when the corresponding varistor is not found for the time being, it can be removed and not used for the time being, as long as the voltage is stable, it will not affect the use of your electrical appliances for a short period of time.

This is because they are usually connected in parallel in circuits.

If the varistor is damaged, do not replace it with a normal resistor, as it has no effect.

Ordinary resistors and varistors are two very different components that cannot be replaced.

What is a varistor? What is a thermistor? How do you measure how good or bad it is? Knowledge.

In my experience, the varistor is broken, and it doesn't hurt to disassemble the varistor, just imagine, thunder can damage your ** machine, the ** machine switch is not worse, and the current ** line is basically indoors, and the outdoor ** cable made by the operator must have lightning protection.

The senior brother upstairs regarded its role as too insignificant, and its high-pressure effect could not be ignored.

With a shake meter and a multimeter, you can measure the breakdown voltage of varistors, diodes and other components.

Regarding the above questions, I won't type if you see it more clearly, so I'll take a look at [how to measure the original text of a varistor** to you].

The use of varistors is generally connected in parallel in the circuit, and when the voltage at both ends changes sharply, the varistor may be short-circuited and the current fuse inside will be blown off, which will play a protective role to a certain extent. The function of the varistor is to protect and stabilize the power supply when there is a high voltage.

One: You can use a suitable voltage source to connect a protection resistor in series to apply voltage to the varistor, measure the voltage value of the varistor, and see if it is on the nominal value, if so, you can consider the component to be good. If there is a large deviation from the nominal value, then there is a problem with this varistor.

2: Use a multimeter, position the file at 10k, connect the meter pen to both ends of the resistor, the multimeter will display the resistance value of the varistor, and the varistor can be inferred from the displayed value to see if the varistor is damaged. However, the accuracy of the multimeter test is not great.

Three: Another method is to use an instrument, "varistor DC parameter instrument" to test, this instrument test is more accurate, this instrument is specifically for varistor testing.

14 represents a diameter of 14mm and a maximum current capacity of 4500A (8 20US), K is the varistor voltage of +-10%, 471 is the varistor voltage, that is, the on-voltage is 470V, and some varistors are printed as 14D471K (such as JSR, CNR brand), where D is round in shape (LS: square) and other parameters are the same as above.

It is a varistor with a varistor voltage of 470V.

Varistors generally do not look at the resistance value;

The general performance is mainly three parameters:

Varistor voltage v1mA: resistance on-voltage (when the resistor current is 1mA, the resistance voltage), generally selected according to the protected circuit;

Leakage current IL: generally refers to the current through the resistance when the applied voltage is 83%V1mA, which is generally required to be 45;

Its resistance value should be close to that of the insulator in the working state, reaching the megaohm level or more, and it is necessary to protect the circuit during the instantaneous overvoltage impulse and when it is turned on, its resistance value is below the ohm level.

If it is necessary to test the resistance, it must be at the specified voltage, which decreases sharply with a logarithmic relationship as the voltage increases.