High frequency dielectric constant tester

ZJD-CHigh frequency dielectric constant tester|Dielectric loss angle factor tester

1、 Product Overview:

High frequency dielectric constant testerThe use of digital LCD display is achieved throughGB1409inQTable method for testing solids/Instrument for analyzing the dielectric constant and dielectric loss factor of liquid insulation materials. It uses a single-chip computer to control the instrument, and the measurement core adopts frequency digital locking, automatic setting of standard frequency test points, and automatic search for resonance pointsQNew technologies such as automatic range conversion and numerical display have improved the tuning circuit, reducing the residual inductance of the tuning test circuit to a low levelvalueAnd retained the originalQThe automatic amplitude stabilization technology in the table makes the new instrument more convenient to use and more accurate in measurement. It can directly read the dielectric constant and dielectric loss results, eliminating the tedious manual calculation. After the new upgrade, the test curve can be viewed through the upper computer software,Beijing Aerospace Vertical and Horizontal Inspection InstrumentIt is a substitute for imported equipmentBeijing Aerospace Zongheng InstrumentProduct. The instrument can measure high-frequency inductance or resonant circuits under high testing frequency conditionsQValue, inductance and distributed capacitance of inductors, capacitance and loss tangent of capacitors, high-frequency dielectric loss of electrical materials, effective parallel and series resistance of high-frequency circuits, characteristic impedance of transmission lines, etc. Origin: Fangshan, Beijing.

2、 Technical features:

DDSDigital composite signal:50KHz-160MHz；

Signal source frequency coverage ratio:1600:1；

Signal source frequency accuracy:6Significant number of digits3×10-5 ±1One word;

Qmeasurement range/QResolution:1-1000automatic/Manual range;4Significant number of digits,resolution0.1；

QMeasurement work error:<5%；

Inductance measurement range/Resolution:1nH-140mH 4Significant number of digits,resolution0.1nH；

Inductance measurement error:<5%；

Tuning capacitor: main capacitor17-240pF；

Direct measurement range of capacitance:1pF～25nF；

Tuning capacitance error/Resolution:±1pFor<1% / 0.1pF；

Resonance point search: automatic scanning;

QQualified preset range:5-1000Sound and light prompts;

QRange switching: automatic/Manual operation;

LCDDisplay parameters:F，L，C，Q，Lt，CtBands, etc;

New feature: automatic deduction of residual inductance and test lead inductance;

New feature: Direct measurement and display of large capacitance values, with measurement values up to25nF；

Power consumption: approximately25W；

Net weight: approximately7kg；

Dimensions: (Width)×tall×Deep)mm：380×132×280.

2、 Compliant with standards:

GB/T1409-2006Recommended methods for measuring the capacitance and dielectric loss factor of electrical insulation materials at power frequency, audio frequency, and high frequency;

GB/T1693-2007Method for determining the dielectric constant and dielectric loss tangent of vulcanized rubber;

ASTM D150-11Standard test method for AC loss characteristics and permittivity (dielectric constant) of solid electrical insulation materials;

GBT5594.4-2015Performance testing methods for ceramic materials in electronic component structures;

3、 Product features:

1Dual scanning technology-Double scanning and automatic tuning search function for testing frequency and tuning capacitance.

2Dual testing element input-Beijing Aerospace Vertical and Horizontal Inspection InstrumentThe test frequency and tuning capacitance value can be entered through digital buttons.

3Dual digital tuning-Digital frequency tuning, digital capacitor tuning.

4Automated measurement technology-Implement the test pieceQAutomatic measurement of values, resonant point frequency, and capacitance.

5Full parameter LCD display–Digital display main tuning capacitor, inductorQValue, signal source frequency, resonant pointer.

6TheDDSDigital direct synthesis signal source-Ensure high fidelity of the source, high precision of frequency, and high stability of amplitude.

7Computer automatic correction technology and testing circuit optimization—Reduce the residual inductance of the test circuit to a low levelvalue，QThe confusion of correcting reading values at different frequencies.

8New feature: Automatic deduction of residual inductance and test lead inductance of the instrument during inductance testing. Greatly improved the accuracy in measuring inductance values, especially small inductance values. This technology is only availableBeijing Aerospace Zongheng InstrumentproductionQThe table has.

9New feature: Direct measurement and display function for large capacitance values, with direct measurement of capacitance values up to25nF(Matching)100uHWhen it comes to inductance. Measure the large capacitance value with just one button. This technology is only availableBeijing Aerospace Vertical and Horizontal Inspection InstrumentproductionQThe table has.

4、 Work environment:

1Environmental temperature:0℃～+40℃；

2Relative humidity:<80％；

3Power supply:220V±22V，50Hz±2.5Hz.

5、 Configuration List:

One host

Nine inductors

A set of fixtures

One liquid cup

One power cord

One data cable

One instruction manual

One certificate of conformity

Warranty card

sixApplicable units:

It can be used in scientific research institutions, schools, such as some research institutes, colleges, or laboratories in metrology and testing departments to use dielectric constant meters to measure the dielectric loss tangent of insulation materialstanδTest the dielectric constant;Beijing Aerospace Vertical and Horizontal Inspection InstrumentIt also applies to factories or units, such as some factories conducting research on the properties of inorganic non-metallic new materials. In addition, in the fields of power, electrical engineering, chemical engineering, etc., such as power plants, power bureau laboratories, transformer factories, capacitor factories, insulation material factories, oil refineries, etc., the dielectric loss and relative dielectric constant of solid and liquid insulation materials are studiedεQuality inspection and so on.

sevenExperimental steps:

1According toQAdjust the instrument according to the operating procedures of the table, select the measurement frequency, and determineC1andQ1The value.

2Place the sample into the test electrode and adjust the capacitorCMake the circuit resonate to achieve maximumQRecord the tuning capacitance valueC2andQ2The value.

3Remove the sample from the test electrode and adjust itCOr test the distance between the electrodes to make the circuit resonate again, and record itCOr test the calibration capacitance value of the electrode andQValue,Beijing Aerospace Vertical and Horizontal Inspection InstrumentAnd calculate the loss angle based on the test valuestanδRelative to dielectric constantε.

4Other high-frequency testing instruments should be operated according to their instructions,Beijing Aerospace Vertical and Horizontal Inspection InstrumentCalculate the loss angle based on the test valuestanδAnd dielectric constantε.

eighty percentTest conditions:

1The surface of the sample should be clean, smooth, and free of cracks, bubbles, and impurities. The surface of the sample should be wiped with a cloth dipped in anhydrous ethanol.

2The sample should be adjusted at least under standard laboratory temperature and humidity24h.

3When there are special requirements for sample processing, it can be carried out according to the product standards specified.

nineTest significance:

1Dielectric constant——Beijing Aerospace Vertical and Horizontal Inspection InstrumentInsulation materials are usually used in two different ways, namely（1）Used to fix electrical network components while insulating them from each other and the ground; （2）Used to act as a dielectric for a certain capacitor. In the first application, it is usually required to have a fixed capacitance as small as possible, while also having acceptable and consistent mechanical, chemical, and heat resistance properties. Therefore, it is required that the capacitance rate has a low value. In the second application, it is required that the capacitance rate has a high value so that the capacitor can be as small as possible in appearance. Sometimes the intermediate value of permittivity is used to evaluate the stress at the edge or end of a conductor in order to minimize AC corona.

2Communication loss——For these two scenarios (as electrical insulation materials and as capacitor dielectrics), AC losses must usually be relatively small to reduce material heating and minimize their impact on the remaining parts of the network. In high-frequency applications, it is particularly required that the loss index has a low value, because for a given loss index, the dielectric loss increases directly with frequency. In certain dielectric structures, such as termination bushings used in testing and dielectrics used in cables, an increase in conductivity typically leads to an increase in losses, which is sometimes introduced to control voltage gradients. When comparing materials with approximately the same capacitance or when using any material under conditions where the capacitance remains essentially constant, this may help consider dissipation factors, power factors, phase angles, or loss angles.

3Relevance——Beijing Aerospace Vertical and Horizontal Inspection InstrumentWhen appropriate correlation data is obtained, dissipation factor or power factor can help display other characteristics of a material, such as dielectric breakdown, moisture content, degree of solidification, and damage caused by any reason. However, the damage caused by thermal aging will not affect the dissipation factor unless the material is subsequently exposed to moisture. When the initial value of the dissipation factor is very important, the changes in dissipation factor with aging are usually very significant.

tenTypical users:

Cangzhou Dahua Group

China University of Metrology

Henan Pingmei Shenma Ju Carbon Materials Co., Ltd

Science and Technology Bureau of Lucheng District, Wenzhou City

Dongguan Chuangchuang Applied Materials Co., Ltd

Beihang University

University of Science and Technology of China

Huizhou Duke New Materials Co., Ltd

Ningbo EastscintillateNew Materials Technology Co., Ltd

Yunnan Nengtou Silicon Material Technology Development Co., Ltd

Tianjin University of Science and Technology

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1、 The concept of dielectric polarization

electricalequipmentinsulationIt plays a crucial role in ensuring the safe operation of equipment and the entire power system.insulationThe function is to separate conductors with different potentials, so that there is no gap between conductorselectricalConnect to maintain different potentials. haveinsulationThe material used is called a dielectric.

The elastic displacement of bound charges and the turning of polar molecules in a dielectric under the action of an electric field are called polarization of the dielectric. The common understanding is that under the action of an electric field, a dielectric transforms from neutral to exhibiting electrical properties externally. The result of polarization is the appearance of equal amounts of opposite numbered charges at both ends of the dielectric along the direction of the electric field, forming a moment. Negative charge appears at the end opposite the positive electrode plate, and positive charge appears at the end opposite the negative electrode plate.

2、 Types of dielectric polarization

According to the material structure of dielectrics, polarization has the following four basic forms.

1. Electronic polarization

Under the action of an external electric field, the electron orbitals in material atoms shift relative to the atomic nucleus, resulting in the generation of induced electric torque, which is called electronic polarization.

Electronic polarization exists in all dielectrics, characterized by a very short time required for the polarization process, approximately10^-15～10^-14s， The degree of polarization depends on the electricityField intensityThe temperature has little effect on electronic polarization, regardless of the power frequency. In addition, electronic polarization belongs to elastic polarization. Without the external electric field, the attractive force between positive and negative charges causes the centers of action of positive and negative charges to coincide, so this polarization has no energy loss.

2. Ionic polarization

In the absence of an external electric field, the centers of action of the positive and negative ions of each molecule coincide in an ionic structured dielectric. Under the action of an external electric field, the electric field force causes relative displacement between positive and negative ions, resulting in the polarity of the entire molecule. This form of polarization is called ionic polarization.

Ionic polarization exists in dielectrics with ionic structures, characterized by a very short time required for the polarization process. about10^-13～10^-12s， The degree of polarization is independent of the power frequency. Ionic polarization also belongs to elastic polarization, with no energy loss. As the temperature increases, the degree of ionic polarization slightly increases due to a decrease in the binding force between ions.

3. Dipole polarization

Polarized dielectrics are composed of dipole molecules. Dipole is a special molecule whose positive and negative charge centers do not coincide, forming a dipole moment, where a single dipole exhibits polarity. When there is no external electric field, due to the chaotic thermal motion of the dipole, the entire dielectric does not exhibit polarity to the outside. Under the action of an external electric field, the originally chaotic distribution of dipoles is oriented in the direction of the electric field, exhibiting polarity. This polarization method is called dipole polarization.

Dipole polarization exists in polar dielectrics, and its characteristic is that the polarization process takes a long time, about10^-10～10^-2s， So the degree of polarization is related to the frequency of the power supply, and when the frequency is high, the dipole cannot rotate in time, resulting in a decrease in polarization rate. Due to the fact that dipoles need to overcome intermolecular forces when turning, i.e. consume electric field energy, which cannot be recovered during recovery, dipole polarization belongs to inelastic polarization.

The temperature has a significant impact on dipole polarization. When the temperature increases, the intermolecular bonding weakens, causing polarization1. Degree of enhancement: However, when the temperature reaches a certain value, due to the intensified thermal motion of molecules, it hinders the dipole from turning towards the working direction along the electric field, resulting in a decrease in polarization degree. So, as the temperature increases, the degree of polarization first increases and then decreases.

The above three polarizations are formed by the elastic displacement or turning of charged particles, all of which occur in a single dielectric and are the most basic forms of polarization.

4. Sandwich polarization

actualelectricalequipmentinsulationUsually using multi-layer dielectricsinsulationDue to the structure, interlayer polarization formed by the movement of charged particles occurs at the interface between different media.

Taking a simple double-layer dielectric as an example, the physical process of interlayer polarization is analyzed below.

As shown in the figureAs shown in TYBZ01401001-1, C₁TheC₂forThe capacitance of each layer of dielectric,G₁TheG₂For the conductivity of each layer of medium,U₁TheU₂For each layer of mediumvoltageOn the switchS just closedAt the moment of the gate, on the mediumvoltageAllocate according to capacitance, i.et＝0

When,U₁/U₂=C₂/C₁When reaching steady state, on the mediumvoltageAllocate according to conductivity, i.eWhen t →∞, U₁/U₂=G₂/G₁.

Due to the different characteristics of the two dielectric layers, in generalC₂/C₁≠G₂/G₁So initiallyvoltageDistribution and Steady StatevoltageThe distribution is usually not the same, that is, the charges on the two layers of media need to be redistributed after closing.

hypothesisC₁＞C₂TheG₁＜G₂, thent→0When,U₁＜U₂；t→∞When,U₁＞U₂BecauseU₁+U₂=U, During the transition processC₁to pass throughG₂Add an extra charge from the power source(referred to as absorbing charge), while C₂to pass throughG₂By releasing a portion of the charge, some charge will accumulate at the interface. The process of accumulating charges at the interface of the interlayer dielectric is called interlayer polarization. The current formed during the process of charge accumulation is called absorption current. Due to the absorption of charges in interlayer polarization, interlayer polarization is equivalent to increasing the equivalent capacitance of the entire dielectric.

Interlayer polarization exists in non-uniform interlayer media. This polarization is inevitably accompanied by energy loss due to the movement and accumulation of charges involved. Due to the fact that the accumulation of charges is carried out through the conductivity of the medium, which is generally small, the polarization process is slow and usually takes seconds to minutes. Therefore, this polarization can only occur in direct current and low-frequency alternating currentvoltageOnly then can it be demonstrated.

3、 Relative dielectric constant of dielectric

Definition

Relative of dielectricsdielectric constantε_rUsed to characterize the strength of the polarization phenomenon of a dielectric under the action of an electric field, its physical meaning represents the multiple of the increase in capacitance or charge between the plates after placing the dielectric between them compared to when the plates are in vacuum.ε_rThe value is determined by the material of the dielectric and varies with temperature and frequency. The calculation formula is

ε_r=ε/ε₀=C/C₀(TYBZ01401001-1)

in the formula ε₀——The vacuumdielectric constant，1/36Π×10^-9F/m；

ε——The medium'sdielectric constant；

C₀——The capacitance of parallel flat capacitors in vacuum, F；

C——The capacitance of a parallel flat capacitor with a solid dielectric inserted between its plates, F。

2. Gas dielectricsdielectric constant

Due to the low density of gas dielectricsdielectric constantThey are all very small, and in engineering applications, all gas dielectricsε_rAll can be regarded as1.

3. Liquid dielectricsdielectric constant

(1) Neutral liquid dielectric. The relative properties of neutral liquid dielectrics (such as transformer oil, benzene, silicone oil, etc.)dielectric constantε_rinWithin the range of 1.8 to 2.8. relativedielectric constantε_rHas a small negative temperature coefficient.

(2) Polarized liquid dielectric. The relative properties of this type of dielectricdielectric constantLarger, its value is3-80, used forinsulationThe medium'sε_r The value is generally within3-6. If used as an impregnating agent for capacitors, it can increase the specific capacitance of the capacitor. However, such liquid dielectrics suffer significant losses in alternating electric fields, hence high voltageinsulationIt is rarely applied.

Polarized dielectricε_rRelated to temperature,ε_rinWhen the temperature is low, it first increases with the increase of temperature, and then when the thermal motion is strong,ε_rIt decreases again as the temperature rises.

Polarized dielectricε_rIt is closely related to the frequency of the power supply. When the frequency is low, dipole molecules can fully follow the alternating electric field and turn,ε_rLarger and its value is independent of frequency size. When the frequency is high, dipole molecules cannot turn and followThe change in the direction of the electric field results in a decrease in polarization, thusε_rreduce.

4. Solid dielectric materialsdielectric constant

(1) Neutral and weakly polarized solid dielectrics. This type of dielectric only has electronic polarization and ionic polarization, relativelydielectric constantSmall, usually2.0 to 2.7. relativedielectric constantThere is a slight decrease with the increase of temperature.

Paraffin, asbestos, polyethylene, polypropylene, inorganic glass, etc. belong to this type of dielectric.

(2) Polarized solid dielectric. The relative properties of this type of dielectricdielectric constantLarger, usually3-6.ε_rThe relationship between temperature, frequency, and polar liquid media is similar.

Resin, fiber, rubber, organic glass, polyvinyl chloride, etc. belong to polar solid dielectrics.

(3) Ionic dielectric. Most solid inorganic compounds belong to ionic structured dielectrics, such as mica, ceramics, etc,ε_rGenerally, it has a positive temperature coefficient, which is around5-8.

4、 The significance of dielectric polarization in engineering practice

(1) Chooseinsulating materialIf capacitors should be selectedε_rLarger dielectrics asinsulating materialThis can reduce the volume and weight per unit capacity of capacitors. for otherselectricalEquipment such as cables should be selectedε_rSmaller dielectric, which can reduce the capacitance of the cable during operationelectricityFlow.

(2) Reasonable coordination of multi-layer media. When several dielectric materials are used in combination, due to the use of ACvoltageAnd impactvoltageUnder the action, the electricity in each layer of the mediumField intensityDistribution andε_rIt is inversely proportional, so it is important to choose the appropriate mediumε_rValue, making the electric field distribution in each layer of the medium more uniform.

(3)dielectric lossRelated to the polarization type of the medium, anddielectric losstoinsulationAging and heatpunctureIt has a significant impact.

(4) IninsulationIn preventive testing, sandwich polarization can be used to determineinsulationMoisture condition.

【 Thinking and Practice 】

What is polarization of dielectric materials?

What are the basic forms of dielectric polarization?

3. Which types of polarization belong to lossless polarization? Which types of polarization belong to lossy polarization?

4. What is relativedielectric constantRelativedielectric constantWhat is the significance in engineering?