The DELTA4000 is an automatic 12 kV insulation power factor/tan delta test set designed for the immediate condition assessment of electrical insulation. In addition to traditional power frequency (50/60 Hz) testing, the DELTA4000 uses 1 Hz power factor/tan delta to enhance power frequency assessment of high voltage transformers, bushings, circuit breakers, cables, lightning arresters, and rotating machines. Using the same connection and software as power frequency tests, 1 Hz improves maintenance planning by reducing the need for historical trending and proprietary databases.
The high power variable frequency design generates its own test signal independent of line frequency quality, and the hardware design uses the latest technology available for digital filtering of the response signal. As a result, the DELTA4000 series produces reliable results and stable readings in the shortest time with the highest accuracy, even in high interference substations.
The DELTA4000 series operates with PowerDB software for automatic testing and reporting or with Delta Control software for real-time manual testing.
Measurements include voltage, current, power (loss), power factor/tan delta, inductance, power factor, and capacitance. The test results are automatically stored in the computer and can also be downloaded directly to a USB drive or a printer.
The DELTA4110 test set is to be used with an external computer (not included), while the DELTA4310A test set comes with its own on-board computer.
The FRAX150 and FRAX200 sweep frequency response analysers (SFRA) are the smallest and most rugged instruments of their type and powerful tools 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 use a special cabling technology that ensures the 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 that reveals a wide range of faults when compared with a reference fingerprint for the same transformer. 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 allows you to present data in an impedance or admittance versus frequency view, a powerful analytical tool for many transformer types.
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 application’s needs. By default, the number of test points used for each frequency sweep is 1046, but you can extend this up to a maximum of 32 000. The typical measurement time is 64 seconds, but a fast mode is available that can deliver 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 with ground cable, four 3 m braid sets, two C clamps, 9 m or 18 m connection cables, a user guide, and Windows software.
The IDAX is an insulation diagnostic analyser based on DFR (Dielectric Frequency Response), also known as FDS (Frequency Domain Spectroscopy). DFR technology is an established test procedure in laboratories that, in an innovative effort by Megger, has been adapted for field use in the IDAX range of instruments.
DFR is the measurement of capacitance and losses (tan delta or power factor) over multiple frequencies. The measured DFR curve is dependent on insulation geometry, moisture, oil conductivity, and temperature. By advanced curve fitting to the reference material model, the IDAX calculates moisture content in solid insulation, the oil’s conductivity at 25 °C reference temperature, and tan delta/power factor at 20 °C reference temperature.
In these calculations, ITC (Individual Temperature Correction), another important Megger innovation, is used to translate test data from the test object temperature to the reference temperatures. The IDAX software incorporates an ITC-corrected frequency sweep designed explicitly to assess instrument transformers and bushings.
Thanks to a novel approach to the combination of time and frequency domain data, the IDAX provides the shortest measurement time in the marketplace for a full DFR measurement from 1 kHz to 10 μHz. Separate reference models are fitted to each data set (time or frequency) prior to transformation and combination, which eliminates the risk of artefacts introduced by approximations or transformation of incomplete data sets.
The IDAX is exceedingly easy to use, with an automated test flow and presentation of results that uses an easy-to-understand ‘traffic light’ system.
The IDAX DFR method is now part of international guides and standards, e.g., Cigre TB 254, Cigre TB 414, Cigre TB 445, Cigre TB 775, IEEE C57.152-2013, IEEE C57.161-2018.
For extended applications, the IDAX interfaces seamlessly with VAX high voltage amplifiers; VAX020 for 2 kV and VAX220/230 for 20/30 kV (on request).
