Digital milliohmmeter MTOU3

portabletransformerlow-resistance

Summary
The MTOU3 is a three-phase winding resistance ohmmeter designed for electro-mechanical testing of power, distribution and instrument transformers. It provides fast, precise winding resistance measurements, automatic adaptive demagnetization and automatic vector confirmation to reduce errors and field interventions.

Key features
The unit integrates multiple functions focused on safety, accuracy and productivity:

• Secure, punctual connections for comprehensive winding resistance assessment.
• Automatic adaptive demagnetization to eliminate the risk of protection trips when the transformer is re-energized.
• Automatic vector confirmation before each test to select the correct transformer connections.
• Dual-winding excitation for rapid, accurate measurements of primary and secondary windings.
• Color-coded extendable cables and clamps to simplify setup and reduce connection errors.
• Vector display aligned with the transformer's nameplate to ensure correct results on the first test.
• Integrated tap-changer control to minimize test time on transformers equipped with tap-changers.

Operational benefits
The MTOU3 improves safety by reducing climbs and personnel exposure, increases reliability of test connections through vector confirmation, and optimizes field productivity via fast measurements, simplified configuration and automatic demagnetization.

Documentation and output formats
Available documentation includes technical datasheets and a user guide. Test results can be exported in Excel and PDF formats and a JSON file is generated for integration with data management systems. The product is compatible with TxU PC Software for data transfer and analysis.

Software support and updates
Software and firmware updates are planned. Documented software versions for TxU PC and embedded software are provided. Installation and update files are supplied to ensure the system remains up to date.

FAQ and practical considerations
Key points from the FAQ include:

• For very large power transformers (> 100 MVA), higher excitation voltages and currents may be required to obtain precise and stable measurements.
• The MTOU3 is available in models adapted to different applications and includes tap-changer control to reduce test times.
• Adaptive demagnetization significantly reduces demagnetization time, especially on large transformers.
• If results are out of range, first check cleanliness and tightness of connections between the instrument and the transformer, then verify instrument reliability using reference devices if necessary.

Troubleshooting and field tips
Selected usage and troubleshooting tips:

• If the unit does not power on, verify the power cord is connected to the instrument and to an appropriate outlet and that the power switch is ON.
• If the unit reports unconnected or reversed leads, check correct connection of the cords to the MTOU3 and to the correct phases.

Technical specifications

• Model: MTOU3
• Type: Three-phase winding resistance ohmmeter for power, distribution and instrument transformers
• Key functions: automatic vector confirmation, adaptive demagnetization, dual-winding excitation
• Connections: color-coded extendable cables and clamps for rapid hookup
• Control: integrated tap-changer control for tests on transformers with on-load or off-load tap-changers
• Test output formats: Excel, PDF and JSON
• Software compatibility: TxU PC Software (referenced version in documentation)
• Applications: electro-mechanical testing of three-phase transformers in power, distribution and instrument environments