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TTRW.20A Three-Phase Winding Resistance & Ratio Analyzer

The TTRW.20A is a 2-in-1 distribution transformer test system, combining three-phase winding resistance testing and transformation ratio testing in a single instrument.
Powered by a large-capacity lithium battery, it allows both tests to be completed with one wiring connection, eliminating rewiring and saving significant time during field commissioning.
Built on a high-performance Linux operating system with A7 + M4 dual-core architecture, the TTRW.20A delivers fast real-time measurement, smooth operation, and exceptional reliability in substation environments.

Key Features

  • 2-in-1 tester: Three-phase winding resistance + transformation ratio in one device

  • One connection, two tests: DCR + TTR without disconnecting leads

  • Three-phase automatic DCR testing for Y, Yn, and Δ windings

  • Calculates three-phase unbalance rate

  • 20 A maximum output current, ideal for low-resistance LV windings

  • Supports three-phase, single-phase, Z-type, PT/CT ratio and polarity tests

  • Includes blind test function

  • Embedded Linux OS → stable, secure, fast

  • A7 + M4 dual-core processor for real-time measurement and smooth UI

  • 7-inch industrial touchscreen (1024 × 600) with jog dial operation

  • Large-capacity lithium battery with built-in charger

  • Wired & wireless communication options (USB + RS232)

  • In-built thermal printer for on-site reporting

    TTRW.20A Transformer Winding ^0…

Technical Specifications

Winding Resistance Test (DCR)

Output Current Measurement Range
20 A 0.5 mΩ – 100 mΩ
10 A 1.0 mΩ – 300 mΩ
5 A 10 mΩ – 1.0 Ω
1 A 200 mΩ – 6.0 Ω
0.1 A 2.0 Ω – 60 Ω
≤10 mA 30 Ω – 25 kΩ

Accuracy: ±(reading × 0.2% + 2)

Transformation Ratio Test (TTR)

  • Measurement Range: 0.9 – 5000

  • Accuracy:

    • ≤500: ±(reading × 0.1% + 2)

    • 500 to ≤3000: ±(reading × 0.2% + 2)

    • 3000: ±(reading × 0.3% + 2)

  • Resolution:

    • 0.9–9.9999 → 0.0001

    • 10–99.999 → 0.001

    • 100–999.99 → 0.01

    • ≥1000 → 0.1

Use Conditions & Physical

Parameter Specification
Power Supply Built-in lithium battery, 7.8 Ah
Charging Voltage AC 220 V
Operating Temperature –10 °C to +50 °C
Relative Humidity ≤90% (non-condensing)
Weight 6.5 kg
Dimensions 318 × 280 × 204 mm

Standard Accessories

  • HV & LV test leads

  • Grounding lead

  • USB cable

  • RS232 cable

  • Thermal printer paper

  • Battery charger

  • Hard carry case

  • User manual

  • Calibration certificate

Optional Accessories

  • Extended test lead sets

  • Rugged transport case

  • Additional printer supplies

  • PC connectivity software upgrades

Applications

  • Winding resistance testing of distribution transformers

  • Three-phase, single-phase, and Z-type transformer TTR testing

  • PT/CT ratio and polarity verification

  • Commissioning, routine maintenance, and fault diagnostics

  • Substation testing with portable battery operation

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