Megger makes winding resistance straightforward

imageedit 2 3116063114Megger, a global manufacturer of electronic test equipment and measuring instruments for electrical power applications, has launched new MTO106 transformer ohmmeter to provide an affordable yet accurate and reliable option for measuring DC winding resistance in smaller distribution and transmission power transformers

The instrument is compact and readily portable – weighs 7.3kg – and, with the lid closed, it has an IP67 ingress protection rating, which means it can be shipped without further protection.

Operation of the MT106 transformer ohmmeter is straightforward and intuitive – users make the ground connection, connect the power, and make connections to the transformer under test using the Kelvin leads supplied. Then, after selecting the required test current, they simply press the start button. The test results are shown clearly on a large backlit display.

To ensure safe operation, audible and visual ‘test active’ indicators operate during the test and, at the end of the test, the winding is automatically discharged with visual and audible indicators in operation. Discharge continues to completion even if the supply to the instrument is turned off. This simple operating procedure means that users need only a small amount of training to operate the instrument safely and obtain results that are accurate and reliable.

The MTO106 offers two test channels with test current manually selectable in five steps up to a maximum of six amps. This allows the current to be chosen to suit the transformer under test, while minimising the risk of heating the windings. The instrument delivers an open-circuit test voltage of up to 48V, ensuring that even larger transformers are saturated rapidly, which reduces the time needed for testing.

This versatile and convenient instrument can be used to carry out winding resistance measurements in line with most major transformer testing standards, including those published by CIGRE, IEEE, IEC and ANSI. It can detect problems such as faulty tap changer contacts, broken conductors, shorted winding disks or layers and poor bushing connections. As well as its primary function of testing transformers, the MT106 can also be used to measure the winding resistance of other inductive assets, such as chokes and motors.

Alain Charles Publishing, University House, 11-13 Lower Grosvenor Place, London, SW1W 0EX, UK
T: +44 20 7834 7676, F: +44 20 7973 0076, W:

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