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体积电阻率表面电阻率测试仪  型号：BEST-121

一、根据欧姆定律，被测电阻Rx等于施加电压V除以通过的电流I。传统的高阻计的工作原理是测量电压V固定，通过测量流过取样电阻的电流I来得到电阻值。从欧姆定律可以看出，由于电流I是与电阻成反比，而不是成正比，所以电阻的显示值是非线性的，即电阻无穷大时，电流为零，即表头的零位处是∞，其附近的刻度非常密，分辨率很低。整个刻度是非线性的。又由于测量不同的电阻时，其电压V也会有些变化，所以普通的高阻计是精度差、分辨率低。

四、测试 

将被测试样用测量电缆线和导线分别与讯号输入端和测试电压输出端连接。 将测试电压选择开关置于所需要的测试电压档。 将“放电-测试”开关置于“测试”档，输入短路开关仍置于“短路”。对试样经一定时间的充电以后（视试样的容量大小而定，一般为15秒。电容量大时，可适当延长充电时间），即可将输入短路开关揿至“测量”进行读数，若发现指针很快打出满刻度，应立即揿输入短路开关，使其置于“短路”， 将“放电-测试”开关置于“放电”档，等查明原因并排除故障后再进行测试。 当输入短路开关置于测量后，如发现表头无读数，或指示很少，可将倍率开关逐步升高，数字显示依次为7、8、9、…直至读数清晰为止（尽量取仪表上1～10的那段刻度）。通过旋转倍率旋钮，使示数处于半偏以内的位置，便于读数。测量时先将RV/RS转换开关置于RV测量体积电阻，然后置于RS测量表面电阻。读数方法如下：表头指示为读数，数字显示为10的指数，单位W。用不同电压进行测量时，其电阻系数不一样，电阻系数标在电压值下方。将仪表上的读数（单位为兆欧）乘以倍率开关所指示的倍率及测试电压开关所指的系数（10V为0.01；100V为0.1；250V为0.25；500V为0.5；1000V为1）即为被测试样的绝缘电阻值。例如：读数为3.5′106W倍率开关所指系数为108，测量电压为100V，则被测电阻值为：3.5′106′108′0.1 =3.5′1013W。 在测试绝缘电阻时，如发现指针有不断上升的现象，这是由于电介质的吸收现象所致，若在很长时间内未能稳定，则一般情况下取接通测试开关后一分钟时的读数作为试样的绝缘电阻值。

一个试样测试完毕，即将输入短路揿键置于“短路”，测试电压控制开关置于“关”后，将方式选择开关拨向放电位置，几分钟后方可取出试样。对电容量较大的试样者需经1分钟左右的放电，方能取出试样，以免受测试系统电容中残余电荷的电击。。若要重复测试时，应将试样上的残留电荷全部放掉方能进行。

然后进入下一个试样的测试：为了操作简便无误，测量绝缘材料体积电阻（Rv）和表面电阻（Rs）时采用了转换开关。当旋钮指在Rv处时，高压电极加上测试电压。保护电极接地，当旋钮指在Rs处时，保护电极加上测试电压，高压电极接地。 仪器使用完毕，应先切断电源，将面板上各开关恢复到测试前的位置，拆除所有接线，将仪器安放保管好。

准备 

使用前，面板上的各开关位置应如下：

ａ） 倍率开关置于灵敏度zui低档位置。

ｂ） 测试电压开关置于“10V”处

c） “放电-测试”开关置于“放电”位置。

d） 电源总开关（POWER）置于“关”。

e） 输入短路揿键置于“短路”。

f） 极性开关置于“0”。

检查测试环境的湿度是否在允许的范围内。尤其当环境湿度高于80%以上时，对测量较高的绝缘电阻（大于10 11Ω及小于10-8 A）时微电流可能会导致较大的误差。

接通电源预热30分钟，将极性开关置于“+”，此时可能发现指示仪表的指针会离开“∞”及“0”处，这时可慢慢调节“∞”及“0”电位器，使指针置于“∞”及“0”处。

五、仪器特征

本仪器测量采用三电极法对试样进行测试，其试验装置主要有平板式电极装置和高阻计两部分组成。基本原理是对试样加入不同挡位的直流电压，流经试样的微弱电流用标准电阻取样放大后，从高阻计上读出。数字直接显示出电阻值,精度高、显示迅速、稳定性好、读数方便。技术指标1、采用高集成度的3 1/2位数字显示。2、量程范围：1×105Ω ～1.999×1014 Ω

3、测试电压为DC100V或DC500V或用户订制

4、工作环境温度：20℃±2℃，湿度：35%±10%RH

5、仪器在稳定的工作电压及无信号输入时1--8小时之间零点漂移小于±5%

6、仪器对标准电阻测量的基本误差：≤±10% 

六、 技术参数 

·         型 号 SB36固体（液体）体积电阻率及表面电阻率测试仪

·         额定电压 10 100 250 500 1000 准确度 ±5 % 

·         电阻测量 1* 106～1* 1017准确度 ±10 % ±20 % 

 ·         微电流测量 1* 105～1* 1014准确度 ±10 % ±20 % 

·         外形尺寸/重量（MM /KG） 380W * 260D * 150H / 10 主要用途及特点: 

·         适用于科研、工厂、学校、企业部门对绝缘材料、电工产品、电子设备以及元件的绝缘测量和高阻值兆欧电阻的测量也可用着微电流测量，是一种直读式和微电流两用仪器。 

测试电压（V） 误 差 

DC—10V ±5% 

DC—50V ±5% 

DC—100V ±5% 

DC—500V ±5% 

DC—1000V ±5% 

Volume resistivity of surface resistivity tester

Digital high resistance, a current measuring instrument type: EST-121: volume resistivity, surface resistivity uses: Instrumentation Test

One, volume resistivity surface resistivity tester overview

This instrument can measure high resistance, and measuring current. The American company In large scale integrated circuit and patented technology, the instrument has the advantages of small volume, light weight, high accuracy. Dual 3.1/2 digital display the resistance high resistance meter and current. Limit from 1× 104 Ω～ 1× 1018 Ω, is currently the most wide measurement range, the most accurate digital ultra high resistance meter. Current measurement range of 2× 10-4 ～ 1× 10-16A. The built-in test voltage is 10/50/100/250/500/1000V adjustable. The instrument has the advantages of high precision, good stability, showing a rapid, easy reading, applied to anti-static products such as anti-static shoes, anti-static plastic rubber products, computer room anti-static floor activities such as the resistance value of the test as well as insulating materials electrical and electronic products insulation resistance measurement. The instrument can measure the resistance, and can directly measure the weak current. 

Instrument is fully consistent with and better than the national standard GB1410 " solid electrical insulating materials, insulation resistance, volume resistivity and surface resistance test method " and " American Standard ASTM D257 DC resistance or conductance of insulating materials test methods " and other standards.

Two, volume resistivity surface resistivity tester main features

Resistance measuring range 0.01× 104 Ω～ 1× 1018 Ω

Current measurement range of 2× 10-4A ～ 1× 10-16A

Small volume, light weight, high accuracy

Resistance, current double display

Good performance is stable, easy reading

All the test voltage （ 10/50/100/250/500/1000V ） test resistance results in reading, is removed from the old high resistance meter in different test voltage or different scale should be multiplied by the coefficient of the inconvenient trouble, allowing the measurement of high resistance as the multimeter is used to measure the general resistance of samples is simple.

Not only can measure high resistance and micro current

Wide application: applied to anti-static products such as anti-static shoes, anti-static plastic rubber products, computer room anti-static floor activities such as resistance testing electrical and electronic products insulation resistance measurement

Three, volume resistivity surface resistivity tester technical indicators

The 1 resistor measurement range: 0.01× 104 Ω～ 1× 1018 Ω.

The 2 current measurement range : 2 × 10-4A～ 1 × 10-16A

3 double header display: 3.1/2 LED display

4 built-in test voltage: 10V, 50V, 100V, 250, 500, 1000V

5 basic accuracy: 1% （ note ）

6: use environment temperature: 0℃ ~ 40 ℃, relative humidity <80%

7 built-in test voltage: 10/50/100/250/500/1000V arbitrary switching

The 8 power supply forms: AC 220V, 50HZ, power consumption is about 5W

Four, volume resistivity surface resistivity meter working principle

According to the Ohm's law, the measured resistance is equal to voltage is applied through Rx V divided by the current I. The traditional high resistance meter is the working principle of measuring voltage V fixed, by measuring the current flows through the sampling resistor I to get the value of resistance. From Ohm's law can be seen, because the current I is inversely proportional to the resistance, but not proportional to the resistance, so the display value is nonlinear, namely the resistance to infinity, the current is zero, i.e., zero is∞, in the vicinity of the scale is very dense, with a low resolution. The scale is nonlinear. Because the measurement of different resistance, the voltage V also vary, so the average high resistance meter is poor accuracy, low resolution.

At the same time measure the voltage across the resistor V and the current through the resistor I, through the interior of the large scale integrated circuit to complete the voltage divided by the current calculation, and then the results obtained after A/D conversion to digital show resistance, even if the voltage across the resistor V and the current through the resistor I is changed at the same time, the display resistance value is not as common due to high resistance meter that measured voltage or current change of V I change, so, even if the measured voltage, resistance, power supply voltage is measured the changes in the results have little effect, the measurement accuracy is very high （ patent ）, theoretically the error can be zero, while the actual error can be done a few thousandths or extremely few.

Typical application

1 measurements of anti-static shoes, conductive shoes resistance value

2, measurement of the antistatic material resistance and resistivity

3, measurement computer room with movable floor system resistance

4, measurement of insulation resistance （ rate）

5, photodiode dark current measurement

6, physics, optics and materials research

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EST-121 volume surface resistivity measuring instrument

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