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HF-RT-207 Micro Ohm Tester
This 0.2 accuracy class micro ohm tester adopts four-wire Kelvin method to test ultra-low resistance from 0.00001Ω to 11Ω. Powered by dry batteries, portable for on-site inspection of breaker contacts, transformer windings and busbar connections in power systems.
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Download datasheet (PDF · 258 KB)
A micro ohm tester is a precision portable measuring instrument designed to accurately detect ultra-low resistance values ranging from microohms to milliohms. Adopting the four-wire Kelvin testing principle, it effectively eliminates lead wire resistance and contact resistance interference, delivering stable, repeatable measurement results for conductive components.
Widely applied in power system inspection, it tests transformer winding contacts, circuit breaker contacts, busbar joints, cable terminals and relay connectors to check connection tightness, oxidation and loosening risks that cause overheating faults. Equipped with constant DC output, digital display and overload protection, the device features compact structure, high anti-interference capability and convenient field operation. It serves as essential test equipment for power maintenance, electrical manufacturing and EPC projects to guarantee safe and reliable power grid operation.
Applications of Micro Ohm Tester
Power Grid & Substation Maintenance
Measure contact resistance of high-voltage circuit breakers, disconnecting switches, earthing switches to judge contact abrasion, oxidation and loose assembly, prevent heating burnout under load current.
Transformer & Reactor Inspection
Test DC resistance of transformer windings, bushing terminals and winding connection joints; detect broken strands, poor welding and internal winding defects efficiently.
Busbar & Power Connection Testing
Check resistance of copper/aluminum busbar splicing points, cable lugs, bolted connectors; verify crimping and installation quality for low-voltage and medium-voltage power distribution systems.
Electrical Component Manufacturing Test
Quality inspection for relays, contactors, switches, conductive bars and motor stator terminals during production and factory acceptance.
Rail Transit & New Energy Industry
Test conductive joints of locomotive power loops, battery pack busbars and photovoltaic combiner box conductive parts to ensure stable current transmission.
Micro Ohm Tester Main Technical Specifications
| No. | Parameter Item | Specification Value |
|---|---|---|
| 1 | Core Performance Description | Core performance parameters of the resistance bridge |
| 2 | Accuracy Class | 0.2 grade |
| 3 | Operating Temperature Range | 5°C ~ 45°C |
| 4 | Measuring Range | 0.00001 ~ 11 Ω; Basic measuring range: 0.01 ~ 11 Ω |
| 5 | Measurement Accuracy | 0.2% |
| 6 | Main Power Supply | 1.5V~2V (built-in power consists of four 1.5V No.1 dry cells connected in parallel) |
| 7 | Galvanometer Operating Power | Operating power supply for transistor galvanometer: two 9V 6F22 batteries connected in parallel |
| 8 | Overall Dimensions | 300×255×150 mm |
| 9 | Instrument Weight | approx. 4.5 kg |
Packing List – Micro Ohm Tester
| No. | Item Description | Qty | Unit | Remarks |
|---|---|---|---|---|
| 1 | Micro Ohm Tester Main Unit | 1 | Set | Complete resistance bridge host |
| 2 | Test Leads & Kelvin Four-wire Test Cables | 1 | Set | For low resistance accurate measurement |
| 3 | Alligator Clips / Measuring Probes | 1 | Pair | Copper high-conductivity clips |
| 4 | Built-in No.1 Dry Batteries | 4 | Pcs | 1.5V, parallel installed inside device |
| 5 | 6F22 9V Batteries for Transistor Galvanometer | 2 | Pcs | For galvanometer power supply |
| 6 | User Operation Manual (English + Chinese) | 1 | Copy | Detailed operation & calibration guide |
| 7 | Factory Calibration Certificate | 1 | Copy | Metrology calibration document |
| 8 | Quality Inspection Report | 1 | Copy | Factory FAT test record |
| 9 | Hard Carrying Case | 1 | Pc | Shockproof portable storage case |
| 10 | Spare Fuse & Small Accessories | 1 | Set | Consumable spare parts |
FAQ for Micro Ohm Tester
Q: What is the core working principle of this micro ohm tester?
A: It adopts Kelvin four-wire measurement technology, which eliminates the resistance interference of test wires and contact points, enabling precise testing of ultra-low resistance values.
Q: What resistance range can this device measure?
A: The total measuring range is 0.00001Ω ~ 11Ω, with the basic reliable measuring range covering 0.01Ω to 11Ω, perfectly suited for tiny contact resistance tests.
Q: What accuracy grade does the instrument belong to?
A: Accuracy class 0.2, with measurement accuracy up to 0.2%, meeting strict power industry inspection and factory acceptance standards.
Q: What is the applicable ambient temperature for daily operation?
A: Normal working temperature range: 5°C ~ 45°C. Avoid using it in overly hot, humid or dusty environments to guarantee long-term precision.
Q: What batteries does the tester use for power supply?
A: Main bridge power: four 1.5V No.1 batteries connected in parallel (1.5V~2V total); Transistor galvanometer power: two parallel 9V 6F22 batteries.
Q: What common scenarios is this micro ohm tester used for?
A: Widely used to test high-voltage breaker contact resistance, transformer winding DC resistance, busbar joint resistance, cable terminal crimping quality and relay contact resistance in substations and electrical workshops.
Q: What are the overall size and weight of the instrument?
A: Outer dimension: 300×255×150 mm; Net weight approx. 4.5kg, lightweight and easy to carry for field on-site maintenance.
Q: Will you provide calibration certificate together with shipment?
A: Yes. Each unit is delivered with an official factory calibration certificate, quality inspection report and bilingual user manual.
Q: Can this tester check loose connections and overheating risks of power fittings?
A: Definitely. Abnormally high resistance readings indicate loose joints, oxidation or poor welding, which will cause heating under load current; early detection effectively prevents power equipment faults.
Q: Is spare parts and after-sales technical support available for overseas customers?
A: We offer lifelong technical consultation, spare parts supply and remote troubleshooting guidance for global buyers.
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