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 greatly simplifies the PD acceptance tests on large power transformers. With its true parallel PD acquisition on up to ten channels, the overall testing period is substantially shortened by features such as the automatic calibration cross coupling matrix. Furthermore, it offers real time parallel PD and RIV measurement on all channels.
A typical package for advanced PD analysis system consists of a multi-channel ICMsystem offering both narrow and wide band PD pattern acquisition according to IEC 60270. The instrument comes with an embedded spectrum analyzer for PD analysis in frequency domain. Moreover, it is an excellent tool to use in case of noisy test environments. New in this 5th generation is the embedded digital storage oscilloscope (DSO) for time domain analysis of electrical and acoustic signals. The ICMsystem software further offers direct transmission of acoustic time domain measurements to the ICMacoustic PD location software, providing an accurate graphical and mathematical triangulation functionality to locate PD defects in the main tank with high precision.
The ICMcompact with SPEC option is a good compromise for routine factory PD testing of distribution class transformers and instrument transformers. Its user friendly interface enables non-PD-experts to efficiently handle factory acceptance tests. The embedded 40 kHz to 10 MHz spectrum analyzer and effective noise gating features are excellent tools to cope with noisy factory environments.
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.