EN
GDHL-300A Intelligent Loop Resistance Tester
GDHL-300A Digital Intelligent High-Precision Loop (Contact) Resistance Tester, Four-Terminal Sensing, Long-Duration High-Current Output, for 220kV+ HV Switchgear & GIS Micro-Ohm Measurement.
- Description
- Specifications
- Applications
- Advantages
- FAQ
- Recommended Products
Description
GDHL-300A is a professional high-current micro-ohmmeter designed for measuring contact/loop resistance of 220kV and above high-voltage circuit breakers, GIS combined electrical appliances, busbars and cable joints in power systems. It strictly complies with DL/T 845.4-2004, IEC 62271-100 and GB 50150-2016 standards, and supports 100A/200A/300A three-gear switchable DC constant current output to meet the test requirements of different voltage levels and equipment capacities.
Adopting high-frequency switching power supply + 16-bit Σ-Δ ADC technology, the instrument features 0.01μΩ ultra-high resolution and ±(0.5% reading + 2μΩ) accuracy. The four-terminal Kelvin measurement completely eliminates lead resistance interference. Long-duration 300A current thoroughly burns off switch contact oxide films and carbon deposits, ensuring true and stable readings even for heavily oxidized contacts.
Specifications
| Parameter | Specification |
|---|---|
| Compliance Standards | DL/T 845.4-2004, IEC 62271-100, GB/T 10230, GB 50150-2016 |
| Test Current | constant current, ripple ≤0.1% |
| Resistance Range | 0–1999.9μΩ (max 50mΩ with extended cables) |
| Resolution | 0.01μΩ (0–99.99μΩ); 0.1μΩ (100–1999.9μΩ) |
| Accuracy | ±(0.5% reading + 2μΩ) |
| Open-Circuit Voltage | ≥15V DC |
| Test Duration | 5s–999s adjustable, continuous output |
| Display | 4.7” color LCD, high brightness, sunlight readable |
| Operation | Touch key, Chinese/English bilingual |
| Data Storage | 1000 groups (with time stamp, ID and test current) |
| Printer | Built-in thermal printer (57mm width) |
| Interface | USB 2.0 (data export) |
| Power Supply | AC 220V±10%, 50Hz±2Hz, ≤500W |
| Operating Temperature | -10℃ ~ +50℃ |
| Humidity | ≤85% RH (non-condensing) |
| Dimensions (L×W×H) | 320×290×260mm |
| Weight | ~8kg |
| Enclosure | Aluminum alloy, IP54 |
Applications
Core Test Objects
- HV circuit breakers: 220kV, 500kV, 1000kV SF6 circuit breakers and GIS combined electrical appliances
- Switchgears: Contact resistance of main contacts, busbar joints and disconnect switches
- Cable systems: High-current cable conductor resistance and welded joint resistance
- Earthing switches: Loop resistance verification of high-voltage earthing switches
Typical Usage Scenarios
- Power companies: Substation preventive maintenance & fault diagnosis of large-capacity equipment
- Switch manufacturers: Factory quality control & type tests of 220kV+ circuit breakers and GIS
- Power plants: Generator circuit breaker and main busbar contact resistance test
- Industrial enterprises: High-current equipment maintenance & safety inspection
Advantages
Compliance with Latest Standards
Fully meets DL/T 845.4-2004, IEC 62271-100, GB 50150-2016 → test results are globally recognized
300A True DC Current
300A high-current output ensures complete oxide film burning for heavily oxidized contacts, providing more accurate and reliable readings than 100A models
Three-Gear Current Switchable
100A/200A/300A three-gear output adapts to different equipment capacities and test requirements, one instrument replaces multiple testers
Four-Terminal Eliminates Lead Error
Kelvin method removes cable resistance interference → readings are stable and repeatable even with 50m long test cables
All-in-One Data & Report
Storage, print, USB export & one-click reports → simplifies on-site documentation
FAQ
Q: Why do 220kV+ breakers need 300A test current?
A: 220kV and above high-voltage circuit breakers have larger contact area and thicker oxide films. 100A current cannot completely break through the oxide layer, leading to false high resistance readings. 300A current simulates the actual operating current of the equipment, ensuring accurate measurement of true contact resistance.
Q: Can it measure very low resistance (≤1μΩ)?
A: Yes. With 0.01μΩ resolution and 300A current, it accurately measures 0.1–1μΩ contact resistance in high-current switchgear and busbar joints.
