One of the final insulation tests on a transformer in a factory test bay is the partial discharge acceptance test according to the IEC standard IEC60076-3 (2000). This specialized test method bases on the major PD test standard IEC60270. According to these standards the following acceptance criteria are recommended:
Oil filled power & distribution transformers:
<300pC at 130% Um
<500pC at 150% Um
Cast resin distribution type transformers & instrument transformers:
<10pC at 130% Um
The ICMsystem (4 or 8 channels) greatly simplifies the PD acceptance test procedure. With its true parallel acquisition of the PD activity on four or eight channels, the overall testing period is substantially shortened. E.g. the cross coupling matrix for the different phases is done automatically while calibrating the test setup. Furthermore, it offers real time parallel PD and RIV measurement on all channels.
An advanced PD analysis system consists of an ICMsystem for PD pattern acquisition, a built-in or external spectrum analyzer for frequency domain analysis, a standard oscilloscope for the evaluation of the time domain signals, and an acoustic measurement system incl. triangulation software. The ICMspectrum software was developed to simplify the use of an external spectrum analyzer in conjunction with the PD measurement. Critical frequencies can easily be detected and filters can be set for in-depth analysis. The ICMacoustic software provides graphical and mathematical evaluation tools to precisely locate internal PD failures.
The ICMcompact with SPEC option comprises a spectrum analyzer and a partial discharge detector in one instrument. This allows PD measurements even in noisy environments like non-shielded test areas. Especially for testing of distribution class transformers the ICMcompact allows measurements with a background noise below the demanded acceptance level.
In addition to the noise suppression functions of the instruments, Power Diagnostix offers a wide range of high voltage filters for induced or applied voltage testing.