How to measure high voltage ceramic capacitors? How to measure the quality of porcelain capacitors

High-voltage ceramic capacitors are high-voltage ceramic capacitors used in power systems, such as metering, energy storage, voltage division and other products of power systems.

High-voltage ceramic capacitors are made of capacitors with high dielectric constant ceramic barium titanate titanium monoxide extruded into a round tube, disc or disc as a medium, and silver plated on the ceramic as an electrode by the burn-out method.

High-voltage ceramic capacitors are tested before leaving the factory, and today we will take a look at the test items of high-voltage capacitors and how these items are measured.

The test of high-voltage ceramic capacitor before leaving the factory is to better check whether it is qualified, whether it meets the customer's requirements, and whether it can guarantee the service life.

The main test items of high-voltage ceramic capacitors are as follows: 1. Series resistance test and insulation resistance test.

2. Withstand voltage test, including 24-hour working test of rated working voltage; It also includes breakdown withstand voltage, that is, destructive test, the critical voltage before the capacitance is broken down is the breakdown voltage (twice the rated voltage at high voltage without breakdown).

3. Tensile test, that is, the firmness of the soldering of the lead wire and the chip.

4. Aging test, the high-voltage ceramic capacitor operates in the simulated working environment for 30 to 60 days, and its attenuation is tested to reduce the changes of its parameters.

5. Positive and negative temperature change rate test, that is, the change rate of capacitance from -40 degrees to +60 degrees.

6. Life test, that is, on the basis of aging test, and then carry out rapid charge and discharge test under high-frequency impulse current on the capacitor, and the number of charge and discharge obtained is the charge and discharge life, note that the life is obtained after a long period of aging.

7. Partial discharge test, that is, partial discharge test.

The above is how to measure high-voltage ceramic capacitors, if you still have questions about this, you can go to some qualified manufacturers to observe how they measure high-voltage ceramic capacitors.

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Capacitance Measurement Method:

1. Direct detection with capacitor file. Some DMMs have the function of measuring capacitance, and their ranges are divided into 2000p, 20n, 200n, 2

and 20 fifth gears. When measuring, the two pins of the discharged capacitor can be directly inserted into the CX jack on the meter board, and the display can be read after selecting the appropriate range.

Data. 2. Detect with resistance gear. If the measurement rate of the digital multimeter is n seconds, then the charging process of the capacitor can be observed every second.

N readings are seen that are independent of each other and increase sequentially. Based on this display feature of the DMM, it is possible to detect the quality of the capacitor and estimate the electricity.

The size of the capacity.

3. Detect with voltage level. Detecting a capacitor with a digital multimeter's DC voltage level is actually an indirect measurement method that can be measured.

220pf 1 F small capacitance capacitor, and can accurately measure the size of the capacitor leakage current.

Capacitance Summary:

Capacitance refers to the ability to hold an electric field. Any electrostatic field is made up of many capacitors, and where there is an electrostatic field, there is a capacitance, and the capacitance is described in terms of an electrostatic field. It is generally believed that

An isolated conductor forms a capacitance with infinity, and the conductor is grounded to the infinity and connected to the earth as a whole. Practical application.

A wide variety of capacitors are used in the manufacture of electronics, and they each play a different role in the circuit. Similar to resistors, they are often referred to simply as capacitors, denoted by the letter C. As the name suggests, a capacitor is a "container that stores electrical charge".

Although there are many varieties of capacitors, their basic structure and principle are the same. A capacitor is formed when two pieces of metal are separated by a substance (solid, gas, or liquid) that are very close to each other. The two pieces of metal are called plates, and the material in between is called the medium.

Capacitors are also divided into fixed capacitance and variable capacitance. However, the most common capacitors are fixed capacitors, and the most common ones are electrolytic capacitors and ceramic capacitors.

Different capacitors have different abilities to store charge. It is specified that the amount of charge stored in a capacitor when a voltage of 1 volt DC is applied to a capacitor is called the capacitance of the capacitor. The basic unit of capacitance is farad (f).

But in fact, farad is a very uncommonly used unit, because the capacitance of capacitors is often much smaller than 1 farad, commonly used microfarad (f), nanofarad (nf), picofaria (pf) (picofaria is also known as picofara), etc., their relationship is: 1 farad (f) = 1000000 microfarad (f) 1 microfarad (f) = 1000 nanofarth (nf) = 1000000 picofara (pf).

The method of measuring the quality of the capacitance of the porcelain tile is as follows:

1. Use the RX10K file of the pointer multimeter to measure whether there is leakage. During normal capacitance measurement, the gauge hand swings slightly to the right, and immediately returns to zero, which means normal. If the pointer stops at a certain resistance value, it indicates that the capacitance is leaking.

2. Use the capacitance file of the digital multimeter to measure the capacity of the capacitor and judge the quality of the ceramic capacitor. Or use a capacitor withstand voltage and leakage current tester to measure, the results are more accurate.

Reading method of porcelain capacitance:

The reading method of porcelain capacitance and the reading method of resistance are basically the same, and there are three kinds of color separation scale method, number standard method and direct standard method. The basic unit of ceramic capacitance is represented by farad (f), and other units are: millimethod (mf), micromethod (f), nano method (nf), and piping method (pf).

Wherein: 1 farad = 1000 millifarnes (mf), 1 millifarth = 1000 microfarads (f), 1 microfarth = 1000 nanofarthic (nf), 1 nanofard = 1000 picofaric socks (pf).

The capacitance value of a ceramic capacitor with a large capacitance is directly indicated on the capacitor, e.g. 10 F 16V. The capacitance value of a ceramic capacitor with a small capacitance is represented by letters or numbers on the capacitance.

Letter notation: 2m = 2000 f, 1p2 = , 2n = 2000 pf.

Digital notation: The three-digit representation is also called the digital representation of capacitance. The first two digits of the three digits are the valid digits of the nominal capacity, and the third digit indicates the number of significant digits followed by zeros, both of which are in pf. <>

1. The differential pressure measurement of the fiber-resistant fiber does not break down at high voltage twice the calibration voltage.

2. Capacity measurement, the capacity is within the specified deviation range.

3. Thermal stability measurement, the measured capacity is within the range of change under the specified high temperature.

4. Moisture resistance measurement of skin destruction, and the measurement capacity in a humid environment is within the range of variation.

5. Anti-aging measurement.

Detection method. 1. Detect small capacitance below 10pf - because the capacity of fixed capacitors below 10pf is too small, it can only be qualitatively checked for leakage, internal short circuit or breakdown by measuring with a multimeter.

When measuring, you can choose to use a multimeter 10k block, and use two meter pens to connect the two pins of the capacitor at will, and the resistance value should be infinity. If the measured resistance (the needle swings to the right) is zero, it means that the capacitor is damaged by leakage or internal breakdown.

2. Detect whether the 10PF 001 F fixed capacitor is charged, and judge its quality by entering the orange wheel. The multimeter uses 1k gear. Both transistors have a value of 100 or more, and the penetration current should be small.

3DG6 and other types of silicon transistors can be selected to form composite tubes. The red and black pencils of the multimeter are connected to the emitter E and collector C of the composite tube, respectively. Due to the amplification effect of the composite transistor, the charging and discharging process of the measured capacitor is amplified, so that the swing amplitude of the multimeter pointer is increased, so as to facilitate observation.

3. For fixed capacitors above 001 F, the 10k block of the multimeter can be used to directly test whether the capacitor has a charging process and whether there is an internal short circuit or leakage, and the capacity of the capacitor can be estimated according to the amplitude of the pointer swinging to the right.

4. It should be noted that during the test operation, especially when measuring the capacitance of the smaller capacity, it is necessary to repeatedly change the contact points of the capacitor to contact A and B, so that the swing of the multimeter pointer can be clearly seen.

Expand the information of the financial circle

There are two types of ceramic capacitors: high-frequency porcelain and low-frequency porcelain. Capacitors with a small positive capacitance temperature coefficient are used as circuit capacitors and pad capacitors in highly stable oscillation circuits.

Low-frequency ceramic dielectric capacitors are limited to bypass or DC blocking in the lower operating frequency of the return path, or where the stability and loss requirements are not high, including high frequency. Such capacitors should not be used in pulsed circuits because they are susceptible to breakdown by impulse voltages.

Class)—miniaturization, high frequency, ultra-low loss, low ESR, high stability, high withstand voltage, high insulation, high reliability, non-polarity, low capacitance, low cost, high temperature resistance, mainly used in high-frequency circuits.

Class)—miniaturization, high specific capacity, medium and high voltage, non-polarity, high reliability, high temperature resistance, low ESR, low cost, mainly used in medium and low frequency circuits as DC-blocking, coupling, bypass and filter capacitors.

The purpose of measuring the capacitance value of a capacitor is to check the change in its capacitance value. Measuring the capacitance can determine whether the internal wiring is correct, whether the insulation is deteriorated due to moisture, whether the component breaks down, and whether the capacitance is reduced due to oil leakage. The following is an introduction to how to measure capacitance.

Multimeter. Capacitance.

01 First of all, before measuring the capacitance, be sure to discharge the capacitor (short circuit both ends of the capacitor after removing the capacitor), otherwise the multimeter may be burned.

02 Then check the capacitance capacity marked on the capacitor label, so that we can choose the format according to the capacitance capacity. Here we take 25 microfartell capacitors as an example.

03 Next, adjust the multimeter to the appropriate capacitance level, we adjust the gear to be greater than the capacitance value on the capacitor label. Here choose 200 micro-methods.

04 Then press the multimeter measurement button, the measurement capacitance button will generally be marked with "CX LX", and a prompt will appear on the screen after pressing.

05 Note: Be sure to remember that the watch pen should be installed to the COM and CX jacks.

06 Finally, if you touch the two ends of the capacitor with two meter pens, the measured value will generally be larger, but as long as the value is close to the label value, then the capacitor is normal and usable.

Capacitance measurement:

Capacitance can be measured with a multimeter. First, select the correct gear of the multimeter, and then connect it with the black watch pen on one side and the red watch pen on the other side. If the hands of the multimeter swing and finally return to their original position, the capacitance is normal.

You can also use the diode gear of the digital multimeter to detect, connect the capacitor with the meter pen, if there is a drop sound, it means that the capacitor is damaged.

Precautions should be taken when testing capacitance

1. When testing the capacitor, if you don't know how to operate, you should contact professional personnel to operate. The capacitance values measured in this way are particularly accurate. And when testing, we must first put the protective measures in place, so that we are not put in danger.

2. And when testing the capacitance, it should be considered according to the specific situation. Let's take a look at the size of the capacitor, if the capacitance is large, you can use the 20 steps of the multimeter. And before use, you should understand the manual of the multimeter clearly.

Because there is a detailed introduction inside the manual, as long as you follow the steps above in the manual, there will be no mistakes.

3. However, before the operation, all the preparations must be in place. In this way, when the capacitance is detected, there will be no emergencies, so that the overall data will be subject to a certain deviation. At the time of testing, the relevant data should be recorded.

In this way, after the test is completed, the overall situation can be understood.