薄膜電容器高壓電橋工頻介電常數(shù)測(cè)試儀概  述

西林電橋,主要用于測(cè)量高壓工業(yè)絕緣材料的介質(zhì)損失角的正切值及電容量。其采用了西林電橋的經(jīng)典線路。主要可以測(cè)量電容器，互感器，變壓器，各種電工油及各種固體絕緣材料在工頻高壓下的介質(zhì)損耗( tgd)和電容量( Cx)以，其測(cè)量線路采用“正接法”即測(cè)量對(duì)地絕緣的試品。電橋由橋體、指另儀、電位跟蹤器組成，本電橋特別適應(yīng)測(cè)量各類(lèi)絕緣油和絕緣材料的介損（tgd）及介電常數(shù)（ε）。

薄膜電容器高壓電橋工頻介電常數(shù)測(cè)試儀技術(shù)指標(biāo)

2.1  測(cè)量范圍及誤差
本電橋的環(huán)境溫度為20±5℃，相對(duì)濕度為30％－80％條件下，應(yīng)滿(mǎn)足下列表中的技術(shù)指示要求。

操作規(guī)程

本儀器必須有專(zhuān)人負(fù)責(zé)保管，使用，非專(zhuān)職操作者應(yīng)在使用前了解和熟悉本說(shuō)明書(shū)，以免造成不必要的損失和事故。

每次使用前應(yīng)仔細(xì)檢查接地線是否完好，確保以后方可通電使用。

接通電源前應(yīng)將靈敏度開(kāi)關(guān)調(diào)到zui低位置。

測(cè)量試品前應(yīng)先對(duì)試品進(jìn)行高壓試驗(yàn)，證明在電橋工作電壓下無(wú)噪聲，電離等現(xiàn)象出現(xiàn)，然后才能進(jìn)行測(cè)試（若試品己做過(guò)高壓試驗(yàn)，該項(xiàng)可不必每次測(cè)量都做）。

對(duì)試品施加高壓時(shí)緩慢升高，不可以加突變電壓。

測(cè)試時(shí)操作人員必須集中思想，工作前做好一切準(zhǔn)備工作，測(cè)試地點(diǎn)周?chē)鷳?yīng)有明顯的標(biāo)記或金屬屏蔽圍成高壓危險(xiǎn)區(qū)，以防止非操作人員闖入。

在測(cè)量過(guò)程中，如有放電管發(fā)光時(shí)，則必須及時(shí)切斷電源，仔細(xì)檢查接線及試品都無(wú)擊穿，待檢查排除故障后，再進(jìn)行高壓測(cè)量工作

橋體的組成

電橋各臂的組成

*臂：由被測(cè)對(duì)象Cx組成Z₁。

第二臂：由高壓標(biāo)準(zhǔn)電容器Cn組成Z₂。

第三臂：由十進(jìn)電阻器10×（1000＋100＋10＋1＋0.1）歐姆和滑線電阻（0-0.13）歐姆組成Z₃。

第四臂：由十進(jìn)電容臂10×（0.1＋0.01＋0.001＋0.0001）uf和可變電容器100pF組成C4再與電組R4并聯(lián)組成Z4。

工作電壓說(shuō)明

在使用中，本電橋頂A，B對(duì)V點(diǎn)的電壓zui高不超過(guò)11V，R3橋臂各盤(pán)的電流不超過(guò)下列規(guī)定：

10×1kΩ                             1max≤15mA

10×100Ω                            1max≤120mA

10×10Ω                             l max≤150mA

用戶(hù)在使用前應(yīng)注意以上的問(wèn)題。如不清楚，可根據(jù)實(shí)驗(yàn)電壓及標(biāo)準(zhǔn)電容量，按以下公式來(lái)計(jì)算出大概的工作電流。

                    I=ω V C  

2-4輔橋的技術(shù)特性：

不失真跟蹤電壓0～11V（有效值）

2-5指零裝置的技術(shù)特性：

在50Hz時(shí)電壓靈敏度不低于1×10^-6V/格

                電流靈敏度不低于2×10^-9 A/格

二次諧波 減不小于25dB

三次諧波 減不小于50dB

電橋的特點(diǎn)；

 l橋體內(nèi)附電位跟蹤器及指零儀，外圍接線及少。

l電橋采用接觸電阻小，機(jī)械壽命長(zhǎng)的十進(jìn)開(kāi)關(guān)，保證測(cè)量的穩(wěn)定性

l儀器具有雙屏蔽，能有效防止外部電磁場(chǎng)的干擾。

l儀器內(nèi)部電阻及電容元件經(jīng)特殊老化處理，使儀器技術(shù)性能穩(wěn)定可靠。

l內(nèi)附高壓電源精度3%

l內(nèi)附標(biāo)準(zhǔn)電容損耗﹤0.00005，名義值100pF

高壓電橋采用典型的西林電橋線路。C4橋臂在基本量程時(shí)，與R4橋臂并聯(lián)，測(cè)量數(shù)值為正損耗因數(shù)。

結(jié)構(gòu)采用了雙層屏蔽。并通過(guò)輔橋的輔助平衡，消除寄生參數(shù)對(duì)電橋平衡的影響。輔橋由電位自動(dòng)電位跟蹤器與內(nèi)層屏蔽（S）組成。

自動(dòng)跟蹤器由電子元器件組成。它在橋頂B處取一輸入電壓，通過(guò)放大后，在內(nèi)屏蔽（S）產(chǎn)生一個(gè)與B電位相等的電壓。

當(dāng)電橋在平衡時(shí)，A,B,S三點(diǎn)電位必然相等，從而達(dá)到自動(dòng)跟蹤的目的。

本電橋在平衡過(guò)程中，輔橋采用自動(dòng)電位跟蹤，在主橋平衡過(guò)程的同時(shí)，輔橋也自動(dòng)跟蹤始終處于平衡的狀態(tài)，用戶(hù)只要對(duì)主橋平衡進(jìn)行操作就能得到可靠的所需數(shù)據(jù)。

同時(shí)也有效的抑制了電壓波動(dòng)對(duì)平衡所帶來(lái)的影響。在指零部分，采用了指針式電表指示，視覺(jué)直觀，分辨清楚，克服了以往振動(dòng)式檢流計(jì)的缺點(diǎn)。

Overview of power frequency dielectric constant tester for thin film capacitor high voltage bridge
Schering bridge, mainly for the tangent of dielectric loss angle measurement of high voltage insulation material industrial value and capacitance. It uses the classic line of Xilin bridge. The main measuring capacitor, transformer, transformer oil, various electrical and various solid dielectric materials at power loss under high pressure (TGD) and capacitance (Cx), its measuring circuit using "positive connection method" to measure the insulation test. Bridge is a bridge, which, another potential tracker, especially suitable for the bridge measurement of dielectric loss of insulating oil and all kinds of insulation materials (TGD) and dielectric constant (E).
Technical index of power frequency dielectric constant tester for thin film capacitor high voltage bridge
2.1 measuring range and error
This bridge is 20 + 5 C ambient temperature, relative humidity 30%80% conditions, should meet the requirements in the following list technical instructions.
Standard Practice for measuring the dielectric constant of the high voltage bridge for thin film capacitors
The instrument must be responsible for the custody of a person, the use of non professional operators should be aware of and use the manual before use, so as to avoid unnecessary losses and accidents.
You should carefully check the grounding wire is intact before each use, ensure that before using electricity.
Switch the power supply to the lowest position before switching on the power supply.
Measured before the high voltage test of the sample, prove that there is no noise in the bridge voltage, appear ionization phenomena, then can be tested (if the sample has done high voltage test, this can not be measured every time do).
When the sample is applied to high pressure, it can be increased slowly, and the voltage can not be changed.
The operator must focus on the test, do all the preparatory work before the test site should be marked around the metal shield or high pressure zone to prevent the formation of non operating personnel.
In the process of measurement, such as discharge light, must be promptly cut off the power supply, carefully check the wiring and the samples are no breakdown, to check after troubleshooting, then pressure measurement
The composition of the dielectric constant of dielectric constant of high voltage bridge for thin film capacitors
Composition of bridge arm
The first arm: the object Cx is composed of Z1.
Second arm: high voltage standard capacitor Cn composed of Z2.
Third arm: by decade resistor 10 * (1000 + 100 + 10 + 1 + 0.1 ohms) and line resistance (0-0.13) ohm Z3.
Fourth arm by arm 10 * decimal capacitor (0.1 + 0.01 + 0.001 + 0.0001) UF and 100pF C4 variable capacitor and electric group R4 composed of Z4.
Thin film capacitor high voltage bridge power frequency dielectric constant tester working voltage explanation
In use, the top of the bridge A, B on the V point of the maximum voltage of not more than 11V, R3 bridge arm of the disk current does not exceed the following requirements:
10 x 1K 1max = 15mA
10 * 100 1max = 120mA
10 * 10 Omega l max = 150mA
Users should pay attention to the above problems before use. If not clear, according to the experimental voltage and standard capacitance, according to the following formula to calculate the approximate working current.
C Omega V I=
Technical characteristics of 2-4 auxiliary bridge:
Undistorted tracking voltage 0 to 11V (RMS)
2-5 refers to the technical characteristics of zero device:
The voltage sensitivity of 50Hz is not less than 1 * 10-6V/
Current sensitivity of not less than 2 x 10-9 A/ lattice
The two harmonic reduction is not less than 25dB
The three harmonic reduction is not less than 50dB
Thin film capacitor high voltage bridge power frequency dielectric constant test instrument;
L bridge body attached to the potential tracker and zero, peripheral wiring and less.
L bridge with small contact resistance, long service life of the mechanical decimal switch, ensure the stability of the measurement
L instrument with double shielding, can effectively prevent the interference of external electromagnetic fields.
L instrument internal resistance and capacitance components through special aging treatment, so that the technical performance of the instrument is stable and reliable.
L with high voltage power supply precision 3%
L with standard capacitance loss is less than 0.00005, the nominal value of 100pF
Thin film capacitor high voltage bridge power frequency dielectric constant tester high voltage bridge adopts typical bridge circuit. The C4 bridge arm is connected with the R4 bridge arm in the basic range, and the measured value is positive loss factor.
The structure adopts double shield. The influence of parasitic parameters on the balance of the bridge is eliminated by the auxiliary bridge. The auxiliary bridge consists of an electric potential automatic tracker and an inner shield (S).
Automatic tracker consists of electronic components. It takes an input voltage at the top of the bridge B, after amplification, the inner shield (S) produces a voltage equal to the B potential.
When the bridge is balanced, A, B, S three point potential must be equal, so as to achieve the purpose of automatic tracking.
The bridge is in balance in the process of the auxiliary bridge by automatic potentiometric tracking, in the balancing process at the same time, the auxiliary bridge also automatic tracking is always in balance, as long as the user of the balance operation can get the necessary data and reliable.
At the same time, it can effectively restrain the influence of voltage fluctuation on balance. In zero part, using a pointer meter indication, visual, distinguish, overcomes the shortcomings of vibration galvanometer.