DC tester UHV-S10A

resistanceintegrated circuitfor transformers

Overview
The instrument delivers high output current with automatic current selection for straightforward operation. It integrates a reliable protection circuit and is housed in a lightweight industrial plastic case for easy transport.

Product parameters
This rapid DC resistance tester is a latest‑generation instrument designed to measure transformer DC resistance, optimized for simultaneous measurement of three‑phase windings in large‑capacity transformers. It performs concurrent DC resistance tests on all three phases to reduce measurement time on site.

Technical parameters
Testing current (single phase): 1A, 5A, 10A, 20A
Testing current (three phase): 1A, 5A, 10A
Measurement ranges (single phase): 1A 10mΩ 20Ω; 5A 1mΩ 4Ω; 10A 1mΩ 2Ω; 20A 1mΩ 1Ω
Measurement ranges (three phase, per phase): 1A 10mΩ 6Ω; 5A 1mΩ 1Ω; 10A 1mΩ 0.6Ω
Measurement accuracy: ±(0.2% full span ± 2 digits)
Maximum resolution: 0.1 mΩ
Data storage capacity: 150 groups
Power supply: AC 220V ±22V, 50Hz ±2Hz
Operating environment: Ambient temperature 0°–40°C; Relative humidity ≤80%

Features

• Simultaneous three‑phase DC resistance measurement of transformer windings, enabling full‑set testing in one operation.
• Compatible with on‑load tap changers: no discharge required before tap adjustment, reducing measurement time to about one‑third compared with sequential single‑phase tests.
• Large LCD screen with clear graphical interface for intuitive operation and easy parameter setting.
• Built‑in panel printer and large non‑volatile memory for storing and printing measurement results on site.
• Stable, fast measurements with good repeatability—suited for field testing of transformer DC resistance.

Matters needing attention

• When measuring an unloaded voltage‑regulating transformer, ensure the device has completed discharge indication before switching the tap changer.
• Do not disconnect wiring during measurement.
• If the charging progress bar and current value remain stalled, the winding resistance may exceed the selected measurement range; press 'Exit', choose a different current range and retry.
• When replacing fuses or accessories, use parts of the same model as the instrument.

Characteristics / technical specifications

• Model: UHV‑S10A
• Functions: Rapid DC resistance measurement for transformer windings with simultaneous three‑phase testing
• Testing currents (single phase): 1A, 5A, 10A, 20A
• Testing currents (three phase): 1A, 5A, 10A
• Measurement ranges: see Technical parameters section
• Accuracy: ±(0.2% full span ± 2 digits)
• Resolution: 0.1 mΩ
• Data storage: 150 groups
• Power supply: AC 220V ±22V, 50Hz ±2Hz
• Operating conditions: 0°–40°C, relative humidity ≤80%
• Display: Large graphical LCD
• Options: Front panel printer, large non‑volatile memory

Precautions for unboxing

• Before opening the box, please ensure that the arrow mark on the outer packaging of the device is facing upwards. Please be careful not to forcefully tap when opening the box to avoid damaging the equipment. Unpacking and removing the equipment, while retaining the packaging and shock absorbers, not only facilitates your future use during transportation and storage, but also plays a role in protecting the environment

Instrument maintenance

• 1. Keep the instrument clean: During use, it is necessary to regularly clean the exterior and interior of the instrument to avoid dust and debris from entering and interfering with normal operation;
• 2. Regularly check the power cord and terminals: The power cord and terminals are critical parts of the instrument, and they should be checked regularly for good contact, looseness, or corrosion;
• 3. Pay attention to the condition of the instrument battery: As the instrument usually relies on battery power supply, regularly check the battery level and service life, and replace it in a timely manner when necessary;
• 4. Check the display screen and buttons: As the interface for operating instruments, the display screen and buttons need to be in normal working condition to avoid problems such as blurry display or stuck buttons.