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TRIORES-20 – 20 A three-phase winding resistance tester
The TRIORES-20 is a fully automatic three-phase winding resistance tester for transformers — current up to 20 A DC, measurement range from 0.1 μΩ to 100,000 Ω, accuracy 0.1%. One connection is sufficient for all three phases. Built-in printer, 7-inch colour touchscreen, demagnetisation, OLTC control and IP67 protection. Available exclusively in the Benelux through IONIO.
When do you use a three-phase winding resistance tester?
The winding resistance of a transformer is a direct indicator of winding condition: elevated resistance points to loose connections, damaged winding conductors or corrosion at terminal points. For three-phase transformers, three measurements are needed — with the TRIORES-20, one connection using the included three-phase cable set is sufficient. The instrument measures all three phases automatically, without repositioning cables between phases. This saves measurement time and eliminates connection errors.
Intelligent Decision Criteria (IDC): stopping at the right moment
The DC test current up to 20 A charges the winding inductance. Only once the current has stabilised is the measured resistance reliable. The TRIORES-20 continuously monitors measurement stability via the IDC algorithm: as soon as the value is stable below a set threshold, the instrument stops automatically and presents the results. Manual stop is also available. This prevents both premature stopping (unreliable values) and unnecessarily long waiting times.
Measurement range and accuracy
The measurement range runs from 0.1 μΩ to 100,000 Ω, divided across four current ranges:
- 1 A – 20 A: range 0.00 μΩ – 50 Ω, accuracy 0.1% ±0.5 μΩ, resolution 0.1 μΩ
- 100 mA – 1 A: range 0.00 mΩ – 500 Ω, accuracy 0.1% ±10 μΩ, resolution 1 μΩ
- 10 mA – 100 mA: range 0.00 mΩ – 5 kΩ, accuracy 0.1% ±100 μΩ, resolution 10 μΩ
- 1 mA – 10 mA: range 5 kΩ – 100 kΩ, accuracy 0.1% ±50 Ω, resolution 10 Ω
Current is adjustable from 0.001 A to 20 A. Test voltage is 50 V. Resolution: 5 digits.
Demagnetisation
Repeated DC measurements can build up remanence (residual magnetism) in the transformer core. This disturbs subsequent measurements and can affect operating characteristics. The TRIORES-20 has a built-in demagnetisation function that demagnetises the core after the test, leaving the transformer in the correct condition.
OLTC control and heat run test
The TRIORES-20 can control on-load tap changers (OLTC) during measurement. This makes it possible to measure all tap positions without changing the test setup — up to 25 tap results are stored per test record. The instrument also supports the heat run test (temperature rise test): measurement of winding resistance under rated load up to 20 A DC, including temperature correction via optional temperature sensor.
Temperature correction and safety with HV present
Via an optional temperature sensor, the TRIORES-20 automatically adjusts measurement results to a reference temperature. If high voltage is detected on the transformer under test, the intelligent software controls the current in a controlled manner and discharges through the voltage channels — protecting both the user and the instrument.
Operation, storage and reporting
The 7-inch colour touchscreen shows all results on a single screen. Internal storage for 100 test records; unlimited storage via USB stick. The built-in 2.28-inch printer produces an immediate hard copy after measurement. Via the included DMP software (USB or optional Bluetooth), measurement data is analysed, edited and archived on PC. Multilingual operation including English.
Model variants
- TRIORES-20 — base model, mains power, USB
- TRIORES-20 BLUE — mains power, USB + Bluetooth
- TRIORES-20B — built-in battery (14.4 V / 6.9 Ah) + USB
- TRIORES-20B BLUE — built-in battery + USB + Bluetooth
All models feature IP67 protection (case closed), built-in printer and 7-inch touchscreen.
Applications
- Winding resistance measurement on three-phase and single-phase power transformers
- Current transformers and voltage transformers (CT/VT)
- Heat run tests per IEC 60076 and IEEE C57
- On-load tap changer (OLTC) testing during maintenance and commissioning
- Factory acceptance tests (FAT) and site acceptance tests (SAT)
- Periodic maintenance of transformers in power plants, industry and distribution networks
Why through IONIO?
IONIO is the exclusive Benelux partner of HighTest Technology and supplies the TRIORES-20 including DMP software, cable set, factory calibration certificate and periodic calibration maintenance. You automatically receive a reminder six weeks before your calibration interval expires. Advice on model selection (battery, Bluetooth, temperature sensor) and commissioning support are included as standard.
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