JW-100B Large Cross-Section Conductor DC Resistance Tester

The tester is manufactured in accordance with therelevant provisions of the national standard GB/T3048-2007 Test methods for electrical properties of electric cables and wires – Part 4: Conductor DC resistance test, and with reference to Part 2: Test of electrical resistivity of metallic materials. It is mainly used for testing of DC resistance of large cross-section conductors, and can also be used independently as 100A (up to 120A) DC standard source, consisting of a 0.05-level DC standard source, a resistance drop measuring plate and a control single chip.
The measuring plate uses C8051F350 single chip, including a 24-bit ADC. Integral non-linearity of ADC is± 15ppm FS (full-scale value), and after calibration, the gain error is ± 0.002%.
The display uses a 5.7”color LCD, and charts and characters are displayed clearly.

Main Technique Specification

Resistance measurement：
Range Recommended Current(A) ResolutionμΩ Error%

10～20μΩ 120～100 0.001   ±(0.1RD+0.02RG)
20～200μΩ 100～50 0.001 ±(0.04RD+0.01RG)
200μΩ～2mΩ 50～50   0.01 ±(0.04RD+0.01RG)
2mΩ～20mΩ 5～0.5   0.1     ±(0.04RD+0.01RG)

RG is the upper limit of the measurement range, and RD is the actual reading of the resistance value.
Description:
1. The recommended value of the test current is applied to a 1 m long copper conductor. For aluminum conductors, the current value should be reduced by half.
2. For known cross-sectional area (mm²) of Rx, input current can also be selected manually as per about 0.6A/mm²,but the maximum current can only be 120A.
3. For selected current ≤ 60A, 1.41 times current may be taken for re-measurement if necessary.
Main Specifications of current source
current range（In）：100A，20A，2A
Capacity:
    Maximum output voltage of each range is 1.5V
Adjustment range: 0～120%（In）
Fineness： 1×10^-4Accuracy：   ±（0.04RD+0.01RG）%
            （RD is the reading RG is the range）
            （100A， 20A，2A）
Load regulation：   ≤±0.01%RG
Power supply：
            single phase 220V±10%，50Hz±5%
Operating environment：
            temperature   20℃±10℃，
            related humidity   ≤85%RH
Dimension： 460×460×175mm³
weight： about 13kg

Main Functions & Features

A four-point method is used for measurement. Known current I is provided by a standard source, which flows through the current terminal of Rx conductor to be tested, and the potential terminal of the conductor (the specified length is typically two end points of 1m) is connected to the measuring plate. In the case that the amplification factorK of the measuring voltage remains unchanged, UI and U are measured under the measured selected current I and current respectively, and Rx=(UI- U)/KI is obtained through computation.
Where, when I= 0, U means the sum of contact potential, thermoelectric potential andbias voltage preloaded to the amplifier to maintain the measured value to be "+".
After the cross-sectional area (mm ²) of conductor Rx to be tested is input, the instrument can automatically select an appropriate current in order to ensure accuracy of measurement and to give a result of the measurement; if re-measurement is needed after measurement, the tester will be started for further measurement.
For a conductor with extra large cross-section <10 μΩ, rough measurement may be made in the range 10μΩ- 20μΩ, and the result helps determinate the length required for compliance with 10μΩ.
If the cross-sectional area is not known, the instrument can automatically select the appropriate current from 0.5A, provided that the measurement time is longer. Note: When the cross-section is small, a conductor, through which 0.5A current is not allowed to flow, cannot be measured with this instrument.
The instrument is equipped with a temperature - digital transducer, and in the range of 5℃- 35℃, the measurement error can be ≤ 0 .25℃ (data from the manufacturer). Able to communicate with the host of the instrument, the transducer can be used to measure the ambient temperature and Rx conductor surface temperature.