Transformer tester UHV-20A

high-voltagelow-resistanceportable

The UHV-20A is a portable DC winding resistance tester designed to measure winding DC resistance of transformers and high-voltage reactors. It provides rapid, repeatable measurements and integrates multiple protection and discharge features to support field acceptance, maintenance and tap-changer adjustment tasks.

Product features

• Compact and portable: reduced size and weight for on-site use.
• Simple operation: intuitive controls for efficient testing.
• Fast, accurate measurements: high-speed acquisition with stable, reproducible results.
• Enhanced safety: automatic discharge and discharge indication plus protections against counter EMF, open-circuit and power loss.

Transport and storage

• Transport: use wooden packing boxes and cushioning materials to prevent damage; if wooden boxes are not used, do not stack devices randomly — maximum packing layers: two; instrument panel should face up during transit.
• Storage: keep the instrument in a dry, clean, ventilated room free of corrosive gases; place a damp-proof pad under the instrument; avoid random stacking without wooden packing.

Applications

• Acceptance testing, maintenance and tap-changer adjustment of power transformers and high-voltage inductive equipment.

Technical specifications

• Model: UHV-20A
• Measure current: 1 A, 5 A, 10 A, 20 A
• Measure range: 1 A: 10 mΩ ~ 20 Ω; 5 A: 1 mΩ ~ 4 Ω; 10 A: 1 mΩ ~ 2 Ω; 20 A: 1 mΩ ~ 1 Ω
• Accuracy: ±0.2% (full range)
• Data storage: 255 records
• Display: LCD; resistance display: 4 1/2 digits
• Maximum resolution: 0.1 mΩ
• Power supply: AC 220 V ±22 V, 50 Hz ±2 Hz (fuse 5 A)
• Maximum power dissipation: 300 W (test current: 10 A/hour)
• Operating environment: temperature 0°C ~ 40°C; relative humidity ≤ 80% RH
• Dimensions: 200 × 400 × 280 mm
• Weight: 6 kg (including accessories)

Working principle

• The DC resistance tester mainly applies DC current to the tested circuit through a standard current source and calculates the resistance value of the circuit according to Ohm's law. The accuracy, stability, and ease of operation of the instrument ensure efficient use in various testing environments. Modern DC resistance testers are also equipped with digital display and storage functions, which can accurately record test results and facilitate subsequent analysis.

Instrument maintenance

• 1. Regular calibration of instruments: To ensure the accuracy and reliability of test results, it is recommended to regularly send the instruments to professional institutions for calibration;
• 2. Replace aging components: The internal components of the instrument may age over time, and in order to ensure stable operation, it is necessary to regularly replace relevant parts;
• 3. Regular battery replacement: The lifespan of batteries is limited, and timely battery replacement can avoid measurement abnormalities caused by insufficient power;
• 4. Carry out daily maintenance: The instrument needs to be cleaned and inspected regularly, mainly including cleaning the housing, checking the power cord and terminals, battery status, display screen and buttons, etc.