MTOU3 Three-Phase Winding Resistance Ohmmeter

With a large power transformer (>100 MVA) you typically require higher excitation voltage and current for accurate and stable winding resistance results.  Whatever your application, there is an MTOU3 model to meet your needs.  All MTOU3s come with built in tap changer control to minimize test time on transformers with built-in OLTCs. 

The MTOU3 uses a demagnetisation process called adaptive demagnetisation. Adaptive demagnetisation uses volts DC to quickly demagnetise any transformer, reducing the time required by more than half on large power transformers. Each MTOU3 comes with auto demagnetisation enabled and intuitively demagnetises the transformer after the completion of winding resistance tests.

When you have questionable results, the next step is to check that the connections from the test set to the transformer are clean and tight. After this, customers often question the reliability/accuracy of the test set. Megger has a portable reference device, the TOS1, for field verification of instrument performance, providing confidence that the correct transformer maintenance decisions can be made.  

The MTOU3 provides data in three formats. Reports of the tests performed are available as Excel or PDF files. These can be used as evidence of work completed and transformer assessment. Also created is a json file. This contains asset and test information and can be used to move data from one TxU test set to another or for import into a data management system, such as PowerDB Lite.