Product Introduction
At present, the conventional QJ44-type DC bridge is widely used for contact resistance measurement in electric power systems. However, the test current of such bridges is only at the milliampere level, making it difficult to detect defects such as reduced cross-sectional area of circuit conductors. When measuring the contact resistance of high-voltage switch circuits, the presence of oil films and oxide layers often results in significantly higher measured values that fail to reflect the true contact resistance.
To address this issue, both the standard SD301-88 AC 500kV Power Equipment Handover and Preventive Test Regulations and the new version of the Preventive Test Regulations for Power Equipment stipulate that the measurement current for circuit breaker and isolating switch contact resistance shall be no less than 100 A DC to ensure the accuracy of test results.
The Switch Micro-Ohmmeter produced by Wuhan UHV is designed in accordance with the implementation standard DL/T 845.4-2004 of the new Electric Power regulations of the People's Republic of China, combining high-frequency switching power supply technology with digital circuit technology. This micro-ohmmeter is suitable for resistance measurement in switch control equipment circuits. contact resistance tester supplier offers high measurement accuracy and stable performance, fully meeting the requirements of high-voltage switch maintenance and factory circuit resistance testing for high-voltage switches.
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Technical parameters
| easuring range | 1～1999μΩ |
| Resolution | 1μΩ |
| Test current | DC 100A fixed output |
| Accuracy | 0.5%±1d |
| Operating mode | Continuous |
| Display mode | 3.5-digit LED display |
| Power supply | AC220V±10% 50Hz |
| Working environment | Temperature: -10℃~40℃, humidity: ≤80%RH |
| Diemension | 390×300×150mm3 |
| Weight | 6kg(excluding attachments) |
Product Characteristics
1. High-Current Output: The Switch Micro-Ohmmeter adopts advanced power supply technology, enabling continuous output of large current over extended periods. It effectively penetrates the oxide film on switch contacts, ensuring reliable test results.
2. Strong Anti-Interference Capability: Even under severe interference conditions, the last digit of the LCD reading remains stable within ±1 count. The contact resistance tester factory provides stable readings and good repeatability.
3. Long Service Life: High-precision resistors are used throughout, effectively eliminating the influence of ambient temperature on measurement results. Additionally, military-grade connectors enhance vibration resistance.
4. Easy to Carry: Compact size and light weight for convenient portability.
Product Function
1. Fixed Gear Output: It provides fixed DC output currents of 50A and 100A, allowing direct measurement of circuit resistance at these currents as required by national standards.
2. High-Precision Measurement: The measuring range is 1 to 1999μΩ with a resolution of 1μΩ and an accuracy of 0.5%±1d. The 3.5-digit LED display provides clear readouts.
3. Continuous High-Current Output: Using advanced power supply technology, the instrument can continuously output a large current for extended periods, effectively breaking through the oxide film on switch contacts for accurate results.
4. Strong Anti-Interference: Under severe interference conditions, the last digit of the LCD reading remains stable within ±1 count, ensuring stable readings and good repeatability.
5. Durable Construction: The use of high-precision resistors effectively eliminates the influence of ambient temperature on measurement results, and military-grade connectors enhance vibration resistance.
6. Portable Design: The contact resistance tester manufacturer is compact (390×300×150mm) and lightweight (6kg), making it easy to carry and use in the field.
Product Advantages
1. Standard-Compliant Testing: It provides the 100A DC test current mandated by standards such as SD301-88 for accurate contact resistance measurement of high-voltage switches, ensuring valid and comparable test results.
2. Effective Oxide Penetration: The large, stable continuous current effectively penetrates the oxide film and oil films that form on contacts, which cause low-current (mA level) bridge methods to read inaccurately high.
3. Stability and Reliability: Strong anti-interference capability ensures stable readings in harsh field environments. The use of high-precision resistors and military connectors enhances measurement accuracy, temperature stability, and vibration resistance, contributing to a long service life.
4. Portability: The contact resistance tester factory is compact and lightweight, making it convenient to carry and use in various field locations.
5. Clear Display: The 3.5-digit LED display provides clear and direct readings of contact resistance.
Application Scenarios of the Contact Resistance Tester
1. Power Utilities and Substations: Used for measuring the contact resistance of high-voltage circuit breakers, isolating switches (disconnectors), busbar joints, and other connection points during routine preventive maintenance and handover tests.
2. Switchgear Manufacturing: Employed by manufacturers for quality control and factory resistance testing of new switchgear, ensuring contact resistance meets design specifications before delivery.
3. Industrial Facilities: Used in industries with large electrical systems (e.g., metal smelting, petrochemicals) for maintenance of high-current switchgear and busbar connections.
4. Testing Laboratories: Used by independent testing labs to perform contact resistance measurements for clients as part of equipment condition assessments.
5. Maintenance and Repair Facilities: Used during maintenance and repair of high-voltage switches to verify the integrity of contacts and connections after service work.
matters needing attention
1. Please read the instruction manual carefully before using the loop resistance tester.
2. Please follow the correct wiring method in the instruction manual to connect the wires.
3. This mirco-ohm meter is not allowed to test the circuit resistance in live circuits.
4. The contact resistance tester manufactures must be reliably grounded during use.
5. Current line users are not allowed to replace them at will.
6. When not in use, the contact resistance tester manufactures should be stored in a ventilated, dry, cool, and clean place, paying attention to moisture and corrosive gases.
FAQs
1. Why is a 100A test current required for contact resistance measurement?
National standards (such as SD301-88 and newer preventive test regulations) mandate a test current of at least 100A DC for circuit breaker and isolating switch contact resistance. Low-current (mA level) tests cannot break through the oxide films and oil layers on contacts, leading to falsely high resistance readings. The high current provides a true measurement of the metallic contact resistance.
2. How does the instrument handle interference on-site?
The contact resistance tester is designed with strong anti-interference capability, ensuring that even under severe interference conditions, the last digit of the LCD reading remains stable at ±1 word. This makes it reliable for use in electrically noisy substation environments.
3. What are the advantages of continuous current output?
Continuous current output, rather than a pulsed current, ensures that the oxide film on the contact surface is effectively broken down, leading to a stable and accurate resistance reading. This overcomes the defect of impulse instantaneous current found in some older designs.
4. Why is a high test current important for contact resistance measurement?
Low-current measurement may be affected by oxide films and surface contamination on electrical contacts. The 100A DC test current helps overcome these effects and provides a more representative measurement of the actual contact resistance.
5. What is the difference between a contact resistance tester and a conventional resistance meter?
Contact resistance tester is specifically designed to measure very low resistance values at the micro-ohm level. Its high test current makes it particularly suitable for evaluating high-current electrical contacts where conventional low-current resistance measurement may not provide representative results.
UHV specializes in the R&D and manufacturing of high-quality electrical testing equipment, capable of accurately measuring the contact resistance of circuit breakers, switchgear, disconnecting switches, and other high-voltage electrical equipment. As an experienced manufacturer and supplier, we offer:
Reliable product quality
Competitive prices
Professional technical support
Flexible customized solutions
Welcome to contact CNUHV for the latest product specifications, availability, and factory-direct prices.
