The ICMsystem is part of the Power Diagnostix ICMseries of digital partial discharge detectors. It is usable over a range of frequencies of applied voltage, including power system frequency (50/60 Hz) and VLF (0.1 Hz).
Partial discharge (PD) measurements are a proven method for effective, nondestructive evaluation of electrical insulation. The Power Diagnostix ICMsystem provides high-resolution digital PD patterns for classification of defects in high voltage insulation systems.
The key to the versatility of the ICMsystem is its modular design. The ICMsystem can be matched up with a variety of special accessories that adapt it to virtually any high-voltage testing environment. A wide range of external preamplifiers provides control of the frequency range in which PD activity is detected, from 40 kHz up to 2 GHz.
Assorted coupling devices, including quadrupoles, coupling capacitors, and current transformers, are available to sense the PD signal in the object under test. Like the other instruments in the ICMseries, the ICMsystem provides effective noise gating that blocks phase-stable noise as well as noise independent of the applied voltage cycle, allowing the ICMsystem to be used in noisy environments without losing significant PD data. Appropriate selection of a preamplifier can assist further in achieving a high signal-to-noise ratio.
The operating parameters of the ICMsystem are fully computer controlled, making it simple to use with the standard ICMsystem software. The PC application includes convenient options for in-depth analysis and printing of stored PD patterns.
Special Applications and Options
For applications such as DC testing or stepped high-voltage testing, the ICMsystem allows recording PD activity versus time (sequentially) instead of versus phase angle.
The optional spectrum function extends the functionality of the ICMsystem to provide a spectrum analyzer and a radio influence voltage meter for RIV measurements according to CISPR and NEMA standard.
A device with a software integrated option for cable fault location (CFL) can perform PD fault location measurements on medium voltage cables by processing partial discharge signals by means of the time domain reflectometry.
Hardware options such as a LAN interface or a built-in modem further extend the capabilities of the ICMsystem. The LAN and modem options permit remote access to data and control of the device.
Multi-channel PD Acquisition
The multi-channel version of the ICMsystem is specifically designed to meet the requirements of partial discharge acceptance tests on large power transformers. The instrument builds on the acquisition core of the standard ICMsystem. However, by introducing an individual amplifier plug-in board for each channel, true parallel acquisition of the discharge magnitude of up to ten channels is achieved. The instrument can be equipped with optional features like RIV or acoustic PD measurement.
For each of the partial discharge measurement channels an independent quadrupole, preamplifier, and amplifier plug-in board is required. Internally, the system controller processes the discharge readings acquired for each channel in a true bipolar peak amplitude acquisition. Optionally, the PD readings can be weighted according to IEC60270-2000. Besides the partial discharge channels, the instrument offers up to ten independent channels for the measurement and sampling of the AC voltage signal provided by the quadrupole.
In addition to the parallel acquisition of the PD activity for the meter and strip chart displays, the pattern acquisition core known from the standard ICMsystem offers the defect identification capabilities of the phase-resolved partial discharge analysis. The influence of power frequency harmonics on the PD pattern, often found with power transformers, can be clearly identified, as the waveform of the AC voltage is available for each channel.
The control software for transformer acceptance testing offers manual and automatic modes for the acceptance test. Reporting is simplified with MS Word and plain text output formats. The reports are based on user-selectable templates.
In acceptance test mode, the software shows up to ten meter displays, each indicating PD level, voltage, and frequency of the specific channel. With the center display, the automatically or manually triggered values are presented in list mode or as a strip chart. Further, during calibration, the crosscoupling matrix between the channels is built-up, which offers essential information in case of PD location measurements on transformers. Additionally, the multichannel ICMsystem software provides the user with all the features known from the standard ICMsystem, such as multi-channel consecutive pattern acquisition, movie-like replay, or statistical evaluation, for instance.