Currently, the power system commonly uses conventional QJ44 dual-arm DC bridges to measure contact resistance. However, the test current of such bridges is only in the mA range, making it difficult to detect defects due to reduced cross-sectional area of the conductor loop. When measuring the contact resistance of high-voltage switch conductive loops, the measurement values are several times larger due to the influence of oil film and oxide layers between contacts, failing to accurately reflect the true contact resistance value. To address this issue, the latest DL/T845.4—2004 "General Technical Conditions for Resistance Measuring Devices: Loop Resistance Tester" standard by the Ministry of Electric Power and the new JJG1052-2009 "Loop Resistance Tester, Direct Resistance Meter Verification Regulation" stipulate that the measurement current for (isolating) switches, circuit breakers, and other contact resistances should be no less than 100A DC, with a minimum current holding time of no less than 60 seconds to ensure accurate test results.

This instrument features an operation panel designed based on ergonomics, conforming to user habits. It employs high-frequency switching power supply and digital circuit technology suitable for measuring loop resistance in switch control devices. The test current follows the national standard recommendation of 100A and 200A DC. It can directly measure loop resistance under 100A and 200A DC conditions. Test results are displayed on a large-screen LCD, with functions including data storage, output printing, and time setting. Additionally, there are 50A and 150A settings available for users; customizable test time, with a maximum setting of 599 seconds, exceeding the standard's requirement of 60 seconds. This is the only domestically produced contact resistance tester capable of achieving a resolution of 0.01μΩ with exceptional stability, outperforming imported high-current micro-ohmmeters. It meets the requirements of electric power departments and high-voltage switch manufacturers for field maintenance and loop resistance testing.

Suitable for high-precision measurement of high-voltage switch contact (loop) resistance, it is also applicable in other scenarios requiring high current and micro-resistance measurements.

1. High Current: Utilizes the latest switching power supply technology to continuously output high currents for extended periods, overcoming the drawbacks of pulse power supplies that only provide instantaneous current. This feature effectively breaks through the oxide film on switch contacts, yielding excellent test results.

2. High Stability: Under severe interference conditions, the last digit on the LCD remains stable within ±1 digit, ensuring stable readings with good repeatability.

3. High Precision: Employs dual-channel high-speed 16-bit Σ-Δ AD sampling and the latest digital signal processing technology, achieving a resolution as high as 0.01μΩ. It is currently the only domestically produced contact resistance tester capable of reaching a 0.01μΩ resolution with exceptional stability, outperforming imported high-current micro-ohmmeters.

4. Intelligent Operation: Features an imported high-performance CPU that automatically switches ranges based on signal magnitude during measurements, ensuring accurate test results. Over-temperature protection circuits halt current output if the instrument exceeds set temperatures, ensuring safe usage.

5. High Quality: Critical components are all imported, coupled with cleverly designed temperature compensation circuits to effectively eliminate the impact of environmental temperature on measurement results. The use of military-grade connectors enhances vibration resistance.

6. Powerful Functionality: Users can freely select currents from 50A, 100A, 150A, to 200A, and set test times anywhere between 5 seconds to 599 seconds. This overcomes limitations found in similar instruments where measurement times cannot be set or continuous operation times are too short, significantly surpassing the performance of other similar devices.

7. User-friendly Interface: Data input is facilitated via a rotary mouse, offering convenience and speed. Users can independently set the instrument's date and time, save measurement data in real-time, and instantly print measurement results.

8. USB Data Transfer: Measurement data can be transferred to a USB flash drive via a USB interface, allowing further analysis and processing using accompanying PC software.

9. Ease of Use: Compact size and lightweight design make it portable and convenient for use.

1. Measurement Range: 0～2999.9μΩ

2. Resolution:

   • 0~99.99: 0.01μΩ

   • 100.0~2999.9: 0.1μΩ

3. Test Current: DC 50A, 100A, 150A, 200A (four fixed output levels)

4. Measurement Accuracy: ±(0.5% rd+2d)

5. Continuous Operation Time: 5s~599s

6. Display Method: Large screen Chinese LCD display

7. Communication Method: USB flash drive transfer

8. Power Supply: AC 220V±10%, 50Hz

9. Total Power Consumption: 1200W

10. Maximum Storage Records: 200 records

11. Operating Environment: Temperature -10℃～40℃, Humidity ≤80% RH

12. Dimensions: 380×310×260 mm³

13. Weight: 11kg (excluding accessories)