IEC62271 100A Digital Contact Resistance Tester Built-in Thermal Printer
Product Description
High-voltage switch circuit resistance testing easily falls into a practical pitfall: equating the screening reading obtained from a short-term current flow with the actual operating condition of the contacts under thermal conditions.
Batch inspections prioritize efficiency, aiming to quickly complete the initial screening of a large number of switches; however, for equipment that has undergone major repairs and has suspected out-of-tolerance issues, it is necessary to observe the trend of contact resistance changes with heat generation under continuous high current to assess thermal stability. Many instruments only have a single test duration, unable to adapt to two drastically different evaluation purposes, easily leading to misjudgments such as "initial screening passed, but excessive heat generation after load operation."
GDHL-100A sets up two sets of current-flow logic for the two types of evaluation targets, outputting a 100A DC test current, strictly adhering to the IEC62271-1 main circuit resistance measurement method.
It employs an independent four-lead Kelvin sampling architecture, physically isolating the current injection circuit from the voltage acquisition circuit, avoiding interference from test cable and fixture contact impedance on micro-ohm measurement results.
It can handle large-scale inspections and screenings of substations, as well as in-depth assessments of the thermal stability of key equipment contacts, and is suitable for various business operations such as switch manufacturing, handover, overhaul, and preventive testing.
What are the advantages of our product?
◆ Two independent current-carrying conditions to match different equipment evaluation purposes:
Rapid screening condition: 100A current carried out for 1 second, suitable for mass screening of switchgear and circuit breakers, quickly completing initial inspections of multiple devices, screening out obviously out-of-tolerance equipment, and improving the efficiency of the entire batch testing operation.
Steady-state thermal assessment condition: 100A continuous current carried out for up to 60 seconds, with real-time updates to resistance readings throughout the process, observing contact resistance drift under continuous high-current heating conditions. Specifically designed for overhauled or suspected defective equipment, reproducing contact conditions under high-current operation, and identifying potential thermal degradation hazards that cannot be detected by short-term testing.
▍The 100A long-term current carrying capacity leads to heat accumulation. The instrument is set with a maximum operating time limit of 60 seconds to protect the power unit and prevent continuous output beyond the limit.
◆ Physically isolated four-lead sampling reduces measurement distortion caused by wiring.
C1/C2 is responsible for outputting large excitation current; P1/P2 only collects voltage under small current conditions. The voltage sampling clamp must be placed inside the current clamp to eliminate lead and clamp contact resistance from the physical path. Even with long test cables used on-site, reliable micro-ohm measurement results can still be obtained, reducing misjudgments caused by improper wiring.
◆ Time-stamped archives fully recreate the test conditions.
The instrument can save up to 100 sets of test records, each with test time and resistance value, distinguishing whether the record used fast mode or steady-state long-time mode. This avoids confusion in later review reports regarding whether the data set is an initial screening reading or a thermal assessment reading. It supports on-board thermal printing, RS232 interface for uploading to a computer, and the accompanying software can export test documents in Word format for easy archiving.
◆ Hardware boundary constraints mitigate the risk of high-current misoperation.
Considering that on-site personnel may easily overlook the thermal effect of a 100A high current, the instrument hardware limits the maximum continuous operating time of 100A to 60 seconds, automatically terminating the output after the timeout to protect internal power devices; the LCD screen simultaneously displays real-time current and resistance readings, facilitating personnel's assessment of whether the excitation has stabilized.
◆ Industrial portable chassis, field-ready.
The integrated portable protective chassis comes standard with an 8-meter-long set of test cables, adaptable to different installation locations of switchgear, and easy to transport and deploy in substations and switchgear production workshops.
Technical Specifications
| Item | Specification |
|---|---|
| Model | GDHL‑100A |
| Rated Test Current | DC 100A |
| Measuring Range | 0‑1999.9 μΩ |
| Resolution | 0.1 μΩ |
| Accuracy | ＜0.5% of reading +0.05% FS |
| Test Modes | Quick Screening (1s) / Steady‑state Thermal Evaluation (up to 60s) |
| Internal Memory | Up to 100 records with timestamp |
| Output Device | Built‑in thermal printer |
| Communication Interface | RS232, data upload to PC for Word report export |
| Power Supply | AC 220V |
| Operating Temperature | -10℃ ~ +40℃ |
| Relative Humidity | ＜80% RH, non‑condensing |
Complete Set Package List
1 × GDHL-100A Loop Resistance Tester Main Unit
1 Set of 8-meter Four-Lead Test Cable Clamps
AC220V Power Cord
Included Host Computer Software CD
Instruction Manual
Factory Inspection Report
Q: How should I choose between the fast mode and the 60-second steady-state mode?
A: For initial screening of large batches of equipment, prioritize the 1-second fast mode to improve work efficiency. When overhauling equipment, replacing contacts, dealing with historical overheating faults, or when reports require thermal stability assessment, select the 60-second steady-state mode to observe resistance changes throughout the energizing process and identify defects that only surface under heating conditions. The values obtained from the two modes cannot be directly compared; the mode used must be noted in the file.
Q: What happens if the voltage clamp and current clamp are reversed in a four-lead connection?
A: If the voltage sampling is placed outside the current clamp, the test results will include the contact resistance between the clamp and the conductor. Measurements at the micro-ohm level will show a significantly inflated value, leading to a false judgment of a faulty switching circuit. On-site wiring must adhere to the rule of "voltage clamp inside, current clamp outside."
Q: Will the stored records differentiate between the two test modes?
A：Saving the archive includes the test time and corresponding test mode information. Later, when retrieving the report, it's possible to determine whether the data came from rapid screening or steady-state thermal assessment, facilitating result review by technicians.