ICMsystem

The ICMsystem is part of the Power Diagnostix ICM series 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 to classify defects in high voltage insulation systems.

Versatility

The key to the versatility of the ICMsystem is its modular design. The ICMsystem can be matched up with various special accessories that adapt it to virtually any high-voltage testing environment. In addition, 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. 

Various 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 ICM series, the ICMsystem provides effective noise gating that blocks phase-stable noise and 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.

PC Software

The operating parameters of the ICMsystem are fully computer-controlled, making it simple to use with standard ICMsystem software. The effective recording of PD patterns is independent of the computer used, so ICMsystem performance is not affected by PC or communications speed limits.

The PC application includes convenient options for in-depth analysis and printing of stored PD patterns.

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. Options such as a multiplexer module, a fibre optic bus and an integrated modem further extend the ICMsystem's capabilities. The multiplexer module, which works with the "ICMmux" software, allows easy selection from eight channels for PD measurement. The fibre optic bus provides advanced protection in hazardous measurement conditions and can connect far apart components in a test. The modem option allows remote data access and control of the ICMsystem. The complete set of ICMsystem commands is also provided. Users can create custom programs to control the ICMsystem for highly specialised applications or integrate them into a general high voltage control test program.

Options: 

• Multiplexer 
• Built-in spectrum analyser
• RIV measurement
• Localisation of cable faults
• Acoustic localisation of partial discharges

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, accurate 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.

Using the multi-channel ICMsystem greatly simplifies partial discharge acceptance tests on large power transformers. The overall testing period is substantially shortened with the accurate parallel acquisition of the partial discharge activity on up to ten channels.

Independent Channels

An independent quadrupole, pre-amplifier, and amplifier plug-in board are required for each partial discharge measurement channel. Internally, the system controller processes the discharge readings acquired for each channel in an accurate bipolar peak amplitude acquisition. Optionally, the PD readings can be weighted according to IEC 60270-2000. Besides the partial discharge channels, the instrument offers the same number of independent channels for measuring and sampling the AC voltage signal provided by the quadrupole.

Pattern Acquisition

In addition to the parallel acquisition of the PD activity for the meter and strip chart displays, the pattern acquisition core 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 identified, as the AC voltage waveform is available for each channel.

Specialised Software

The ICMsystem 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 eight-meter displays, each indicating PD level, voltage, and frequency of the specific channel. The automatically or manually triggered values are presented in list mode or as a strip chart with the centre display. Further, during calibration, the cross-coupling matrix between the channels is built up, which offers essential information in PD location measurements on transformers. Additionally, the multi-channel 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.