Dual Canopy Mechanic Electrical Engineering Co., Ltd. is one of the leading manufacturers and suppliers of 100A/200A Contact Resistance Tester in China. Please feel free to wholesale discount products for sale here and get quotation from our factory. Customized orders are welcome.
What is the introduction to the equipment?
The 100A/200A Contact Resistance Tester is designed to measure the low-value resistance (typically in the micro-ohm or milli-ohm range) within the conductive circuits of power equipment. By performing loop resistance tests on components such as circuit breaker contacts, disconnector blades, busbar joints, and cable connections, the device assists users in identifying potential hazards-such as insufficient contact pressure, contact erosion, loose connection bolts, surface oxidation, or poor crimping-that could lead to overheating. Ultimately, it provides quantitative data to serve as a reliable basis for maintenance decision-making and acceptance evaluations.
What are the key technical highlights of the equipment?
1. High-Current Measurement Technology (Key Differentiator)
High Current Output: Offers multiple high-current output ranges, such as 100A, 200A, 400A, and 600A. In accordance with national standards (e.g., DL/T 845.3), the test current used for measuring switch contact resistance must not be less than 100A.
Oxide Film Elimination: The high current effectively breaks down the oxide films and surface contaminants present on the contacts, thereby measuring the true contact resistance rather than an "apparent resistance" that includes the resistance of the oxide layer.
Constant Current Source Design: Employs high-precision constant current source technology to ensure current stability despite variations in load, thereby enhancing measurement accuracy.
2. Four-Wire Measurement Method (Kelvin Method)
Principle Advantages: Utilizes a four-terminal measurement configuration where the current leads are separated from the voltage leads. This method completely eliminates the influence of the test leads' own resistance and contact resistance on the measurement results, ensuring accuracy at the micro-ohm level.
3. Long-Duration Measurement Mode (Signature Feature)
Continuous Energization: Certain advanced models support continuous-energization measurements over extended periods (e.g., 1 minute, 5 minutes, or longer). This capability complies with specific regulatory standards and allows for the observation of contact temperature rise effects or resistance stability under prolonged current flow, thereby providing a more realistic assessment of the contacts' aging status.
4. Data Processing and Correction
Temperature Conversion: Features a built-in temperature sensor interface that supports the automatic conversion of measured resistance values to a standard reference temperature (e.g., 20°C), based on either the ambient temperature or the contact temperature, facilitating easy comparative analysis.
Automatic Pass/Fail Judgment: Automatically evaluates whether the test results meet acceptance criteria based on pre-configured standard thresholds (e.g., the maximum allowable contact resistance for a circuit breaker).
5. Portability and Interference Immunity
Portable Design: Features a lightweight chassis design, making it easy to transport to substations for on-site inspections and maintenance.
Interference Immunity: Specifically engineered for the harsh electromagnetic environments found in substations, the device employs a combination of hardware filtering and software algorithms to ensure data stability and reliability even in the presence of strong electromagnetic interference.
Where are these products applied?
1. High-Voltage Circuit Breaker Maintenance
Contact Resistance Measurement: Measures the contact resistance of the circuit breaker's main contacts. This serves as a critical indicator for assessing the condition of the breaker's conductive circuit. Excessively high resistance suggests contact wear, insufficient contact pressure, or surface oxidation.
Open/Close State Verification: Verifies circuit continuity when the circuit breaker is in both the open (tripped) and closed (engaged) positions.
GIS (Gas-Insulated Switchgear): Applicable for measuring the contact resistance of internal switching contacts within GIS units, typically utilized in conjunction with specialized connection cables.
2. Disconnectors and Earthing Switches
Contact Resistance Testing: The contact resistance of disconnectors and earthing switches directly impacts the reliability of current conduction. Regular measurement helps prevent equipment overheating incidents caused by poor contact.
Mechanism Operation Coordination: Certain models can be integrated with switch operation analysis to monitor resistance fluctuations during the switching process.
3. Busbar and Connection Component Inspection
Busbar Joints: Measures the contact resistance between busbar sections and at busbar-to-equipment connection points to identify potential overheating hazards.
Cable Terminations: Tests the resistance at the connection points between cable heads and associated equipment.
4. Power Equipment Manufacturing and Factory Testing
Type Testing: Switchgear manufacturers conduct routine testing prior to product shipment to ensure that contact resistance values comply with technical standards (e.g., the limits specified in IEC 62271-1).
Weld Quality Assessment: Evaluates the quality of welded joints within the conductive circuit.
Warranty Commitment: A free 12-month warranty is provided for the complete unit. During the warranty period, any malfunctions not caused by human error will be repaired or have their components replaced free of charge.Remote Technical Support: Assistance in troubleshooting common issues such as unstable readings, abnormally high values, and anomalous inter-phase discrepancies.
Spare Parts Supply: Jigs, test leads, fuses, power adapters, and other components are available for long-term supply.
Repair and Calibration: Support for factory-based inspection, repair, and calibration services to meet project acceptance and audit requirements.
Retraining Services: Remote training is available during personnel turnover to ensure standardized testing methodologies and recording protocols.
Q1: Must the circuit breaker be closed when performing a loop resistance test?
A:Typically, the test must be conducted with the main circuit in the closed state to accurately assess the actual contact condition between the contacts and the conductive loop.
Q2: What are the most common reasons for a measured resistance value being higher than expected?
A: Common causes include poor contact at the test clamps, oxidation or contamination of contact surfaces, loose connections, or contact erosion. It is recommended to first rule out issues related to the clamps and test points before concluding that there is a problem with the equipment itself.
Q3: Does a higher test current necessarily yield more accurate results?
A: Not necessarily; a higher current is not always better. You should select an appropriate current range based on relevant regulations and the specific conditions of the equipment being tested, while also paying close attention to temperature rise and controlling the duration of the test.
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