薄膜电容器高压电桥工频介电常数测试仪概  述

西林电桥,主要用于测量高压工业绝缘材料的介质损失角的正切值及电容量。其采用了西林电桥的经典线路。主要可以测量电容器，互感器，变压器，各种电工油及各种固体绝缘材料在工频高压下的介质损耗( tgd)和电容量( Cx)以，其测量线路采用“正接法”即测量对地绝缘的试品。电桥由桥体、指另仪、电位跟踪器组成，本电桥特别适应测量各类绝缘油和绝缘材料的介损（tgd）及介电常数（ε）。

薄膜电容器高压电桥工频介电常数测试仪技术指标

2.1  测量范围及误差
本电桥的环境温度为20±5℃，相对湿度为30％－80％条件下，应满足下列表中的技术指示要求。

操作规程

本仪器必须有专人负责保管，使用，非专职操作者应在使用前了解和熟悉本说明书，以免造成不必要的损失和事故。

每次使用前应仔细检查接地线是否完好，确保以后方可通电使用。

接通电源前应将灵敏度开关调到zui低位置。

测量试品前应先对试品进行高压试验，证明在电桥工作电压下无噪声，电离等现象出现，然后才能进行测试（若试品己做过高压试验，该项可不必每次测量都做）。

对试品施加高压时缓慢升高，不可以加突变电压。

测试时操作人员必须集中思想，工作前做好一切准备工作，测试地点周围应有明显的标记或金属屏蔽围成高压危险区，以防止非操作人员闯入。

在测量过程中，如有放电管发光时，则必须及时切断电源，仔细检查接线及试品都无击穿，待检查排除故障后，再进行高压测量工作

桥体的组成

电桥各臂的组成

*臂：由被测对象Cx组成Z₁。

第二臂：由高压标准电容器Cn组成Z₂。

第三臂：由十进电阻器10×（1000＋100＋10＋1＋0.1）欧姆和滑线电阻（0-0.13）欧姆组成Z₃。

第四臂：由十进电容臂10×（0.1＋0.01＋0.001＋0.0001）uf和可变电容器100pF组成C4再与电组R4并联组成Z4。

工作电压说明

在使用中，本电桥顶A，B对V点的电压zui高不超过11V，R3桥臂各盘的电流不超过下列规定：

10×1kΩ                             1max≤15mA

10×100Ω                            1max≤120mA

10×10Ω                             l max≤150mA

用户在使用前应注意以上的问题。如不清楚，可根据实验电压及标准电容量，按以下公式来计算出大概的工作电流。

                    I=ω V C  

2-4辅桥的技术特性：

不失真跟踪电压0～11V（有效值）

2-5指零装置的技术特性：

在50Hz时电压灵敏度不低于1×10^-6V/格

                电流灵敏度不低于2×10^-9 A/格

二次谐波 减不小于25dB

三次谐波 减不小于50dB

电桥的特点；

 l桥体内附电位跟踪器及指零仪，外围接线及少。

l电桥采用接触电阻小，机械寿命长的十进开关，保证测量的稳定性

l仪器具有双屏蔽，能有效防止外部电磁场的干扰。

l仪器内部电阻及电容元件经特殊老化处理，使仪器技术性能稳定可靠。

l内附高压电源精度3%

l内附标准电容损耗﹤0.00005，名义值100pF

高压电桥采用典型的西林电桥线路。C4桥臂在基本量程时，与R4桥臂并联，测量数值为正损耗因数。

结构采用了双层屏蔽。并通过辅桥的辅助平衡，消除寄生参数对电桥平衡的影响。辅桥由电位自动电位跟踪器与内层屏蔽（S）组成。

自动跟踪器由电子元器件组成。它在桥顶B处取一输入电压，通过放大后，在内屏蔽（S）产生一个与B电位相等的电压。

当电桥在平衡时，A,B,S三点电位必然相等，从而达到自动跟踪的目的。

本电桥在平衡过程中，辅桥采用自动电位跟踪，在主桥平衡过程的同时，辅桥也自动跟踪始终处于平衡的状态，用户只要对主桥平衡进行操作就能得到可靠的所需数据。

同时也有效的抑制了电压波动对平衡所带来的影响。在指零部分，采用了指针式电表指示，视觉直观，分辨清楚，克服了以往振动式检流计的缺点。

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.