Resistance tester UHV-50A

integrityDCstator winding

Overview
The UHV-50A transformer DC winding resistance tester adopts an updated power design to deliver stable performance, fast measurement and high repeatability. It is intended for accurate DC resistance measurement of transformer windings and high‑power inductive equipment, suitable for workshop testing, R&D and field maintenance.

Technical parameters
Test current: 2.5 A, 5 A, 10 A, 20 A, 50 A
Measuring ranges: 2.5 A: 10 mΩ – 8 Ω; 5 A: 1 mΩ – 4 Ω; 10 A: 1 mΩ – 2 Ω; 20 A: 1 mΩ – 1 Ω; 50 A: 1 mΩ – 500 mΩ
Measurement accuracy: ±0.2% of full scale ±2 digits
Data storage: 255 records
Display: LCD, resistance displayed on 4 1/2 digits
Maximum resolution: 0.1 μΩ
Power supply: AC 220 V ±22 V, 50 Hz ±2 Hz (fuse 5 A)
Maximum power consumption: 1500 W (at 10 A test current)
Operating environment: 0 °C to 40 °C; relative humidity ≤ 80%
Dimensions: 440 × 230 × 490 mm
Weight: 16 kg (with accessories)

Features

• Compact size and lightweight design for workshop and field use.
• Menu operation in Chinese with clear interface for repeatable workflows.
• Fast measurement cycle with stable and accurate results.
• Automatic discharge and discharge-indication functions to reduce handling errors and enhance safety.

Importance of Instruments
Accurate DC resistance measurement is critical for assessing winding integrity, diagnosing faults and verifying connection quality in transformers and inductive equipment. The tester measures resistance based on Ohm's law: precise current injection and voltage measurement are converted to a resistance value by the instrument electronics, ensuring reliable diagnostic data for maintenance and quality control.

Application area
The UHV-50A is used in transformer manufacturing and testing, power system maintenance, electrical equipment production, laboratory R&D and other fields where precise low-resistance measurement is required (including semiconductor processes, materials research and certain biomedical impedance tests).

Characteristics / Technical specifications

• Model: UHV-50A
• Test currents available: 2.5 A, 5 A, 10 A, 20 A, 50 A
• Measuring ranges by test current: 2.5 A (10 mΩ–8 Ω), 5 A (1 mΩ–4 Ω), 10 A (1 mΩ–2 Ω), 20 A (1 mΩ–1 Ω), 50 A (1 mΩ–500 mΩ)
• Accuracy: ±0.2% of full scale ±2 digits
• Data storage: up to 255 records
• Display: LCD, resistance shown as 4 1/2 digits
• Maximum resolution: 0.1 μΩ
• Power supply: AC 220 V ±22 V, 50 Hz ±2 Hz (fuse 5 A)
• Maximum power consumption: 1500 W (at 10 A)
• Operating environment: 0 °C to 40 °C; relative humidity ≤ 80%
• Dimensions: 440 × 230 × 490 mm
• Weight: 16 kg (with accessories)
• Safety: automatic discharge and discharge-indication functions

Instrument precautions

• 1. Safe operation: During the testing process, attention should be paid to safe operation. Ensure that the circuit is in a closed state and follow the correct operating procedures to avoid electric shock or other accidents.
• 2. Ensure circuit stability: Before conducting testing, ensure that the circuit is in a stable state to avoid interference with the test results. You can wait for a period of time to stabilize the circuit before testing.
• 3. Correctly select the test gear: When selecting the test gear, the appropriate gear should be chosen based on the resistance value of the test resistor. Choosing a gear that is too small may cause instrument overload, while choosing a gear that is too large may result in inaccurate test results. If the resistance range of the test resistor is uncertain, a smaller gear can be selected for preliminary testing, and then the appropriate gear can be selected for precise testing based on the test results.
• 4. Avoid interference sources: During testing, efforts should be made to avoid the presence of interference sources, such as changes in other circuit currents, strong magnetic fields, etc. These interference sources may interfere with the test results, resulting in inaccurate test results.