The FRAX series of sweep frequency response analysers (SFRA) is one of the smallest and most rugged instruments of its type and a powerful tool for revealing potential electrical and mechanical problems in power transformers, many of which are difficult or impossible to detect using other methods. 

Meeting all international standards for SFRA measurements, these innovative instruments offer a larger dynamic range and better accuracy than any other comparable test sets currently available. In addition, for the test connections to the transformer, they make use of a special cabling technology that ensures repeatability of results.

The FRAX series operates by applying a sweep frequency test signal to the transformer and monitoring its response. The result is a unique fingerprint which, when compared with a reference fingerprint for the same transformer, reveals a wide range of faults. These include winding deformations and displacements, shorted and open windings, loose and broken clamping structures, core connection problems, core movement, and hoop buckling.

Megger’s FRAX series incorporates powerful analysis and support software. In addition to offering the traditional magnitude versus frequency/phase display, this software also allows users to present data in an impedance or admittance versus frequency view, which is a powerful analytical tool for many types of transformer.

The test frequency range covered by the FRAX is 0.1 Hz to 25 MHz, and you can set the range employed for individual tests to match the needs of the application. By default, the number of test points used for each frequency sweep is 1046, but you can choose to extend this up to a maximum of 32 000. Typical measurement time is 64 seconds, but a fast mode is available that is capable of delivering results in just 37 seconds.

Small and easy to carry, with an operating temperature range of -20 ºC to +50 ºC, the FRAX sweep frequency response analysers are ideal for use in the field. They are supplied complete with ground cable, four 3 m braid sets, two C clamps, an 18 m generator cable, an 18 m test cable, user manual, and Windows software.

There are three models in the FRAX series:

• FRAX099: optional battery, able to use a USB drive for exchanging data with an external laptop 
• FRAX101: optional battery, supports Bluetooth for exchanging data with an external laptop, includes built-in ground loop detector
• FRAX150: mains-operated with an integral PC that has a high-resolution colour screen featuring a powerful backlight that makes it easy to read even in direct sunlight and includes built-in ground loop detector