Megger TAU3 True Three-Phase Transformer Winding Analyser

The Megger TAU3 True Three-Phase Transformer Winding Analyser allows users to power through transformer electromechanical tests, and can perform polarity validation, turns ratio, winding resistance, and demagnetisation tests with the same one-time lead connection. The TAU3 is an advanced, lightweight test solution for power, instrument (CTs/PTs/VTs), and distribution transformers. Using patent-pending step-up excitation, it delivers the necessary AC/DC voltage and current with minimal user input to provide fast and accurate results. A single ladder climb and one-time lead connection save time in the field, while safety features, including a key lock, interlock, and emergency stop, ensure safe and secure operation. Its shock-mounted electronics are housed in a compact, wheeled, watertight case up to 50% lighter and smaller than traditional test systems.

The TAU3 combines multiple functions into one portable unit, and automatically discovers and validates vector groups to prevent costly errors, pinpointing phase issues and detecting core or winding defects through turns ratio and excitation current tests, and identifying deterioration with precise phase angle deviation measurements. It further assesses winding and core health with magnetic balance testing, while three-phase dual winding DC output allows fast, accurate winding resistance measurements without lead changes. Automatic adaptive demagnetisation ensures accurate results and prevents nuisance trips after each test. For tap changers, make-before-break continuity checks verify connectios, and One-touch OLTC automates testing across all taps with a single click, available for both AC and DC. The TAU3 is designed to simplify transformer testing, reduce time in the field, and deliver unmatched accuracy in a rugged, portable package.

Software, Saving, and Printing Results

The TAU3 features an intuitive 10.1-inch touchscreen with large, clear control and on-screen vectors to verify that the test setup matches the transformer nameplate. Results are automatically grouped by file name and can be exported in XLSX or PDF format for easy reporting, emailing, or importing into PowerDB. An optional USB printer enables instant hard copies, and when connected to a PC the TAU3 appears as a USB drive containing the user manual, data sheet, and PC application installer. For advanced workflows, the TAU3 integrates with PowerDB for consistent test reporting across Megger instruments, or it can be controlled via a custom API (available under NDA) for organisation requiring bespoke automation. The unit also supports advanced diagnostics including dynamic resistance measurements for OLTCs, winding resistance cool-down analysis to determine maximum operating temperature, and dry-out monitoring to track winding temperature stability before energisation.

Megger part number: TAU3

Key Features

• Performs polarity validation, turns ratio, winding resistance, and demagnetisation with a single lead connection
• Lightweight, compact, wheeled, watertight case, which is up to 50% smaller and lighter than traditional systems
• Patent-pending step-up excitation delivers precise AC/DC voltage and current with minimal user input
• Built-in safety with key lock, interlock, and emergency stop
• Automatic vector group discovery and validation to prevent errors
• Detects phase issues, core/winding defects, and deterioration with ratio, excitation current, and phase angle deviation tests
• Magnetic balance test for winding and core health assessment
• Three-phase dual winding DC output for fast, accurate resistance measurements without lead changes
• Automatic adaptive demagnetisation after each resistance test
• Tap changer testing with make-before-break continuity check and One-touch OLTC automation (AC and DC)
• Intuitive 10.1-inch touchscreen with on-screen vectors and simple navigation
• Results exportable in XLSX/PDF; optional USB printer for instant printouts
• Appears as a USB drive when connected to a PC with built-in manual, datasheet, and software
• PowerDB integration for advanced reporting, plus optional API for custom automation
• Advanced diagnostics such as dynamic resistance measurements (DRM), winding resistance cool-down temperature, and dry-out monitoring