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AIAcompact Portable acoustic insulation analyser

Power Diagnostix’s AIAcompact allows acoustic and UHF PD measurements for insulation assessment

The AIAcompact is a portable instrument for in-service acoustic and electric ultra-high frequency (UHF) partial discharge (PD) measurements on high voltage assets

Insulation assessment without operational interruption

Mobile testing on demand

Versatile application possibilities

Available in three housing versions

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About the product

Power Diagnostix’s AIAcompact portable acoustic insulation analyser has been designed for the acoustic and electric analysis of the insulation condition of high voltage assets, such as:

Gas-insulated switchgears (GIS)
Gas-insulated lines (GIL)
Power transformers
Distribution transformers
Cable accessories

To be suitable for all these applications, the instrument adapts to a variety of piezoelectric acoustic sensors and pre-processing units. It can be used with acoustic sensors and external ultra-high frequency sensors as well as embedded UHF sensors of the tested asset.

The AIAcompact has a built-in liquid crystal display (LCD) and is controlled by two columns of buttons. The function of the left column is indicated with the LCD (soft keys), while the right column has fixed assigned functions. The instrument is designed as a portable standalone detector,; however, it is equipped with a USB interface so it can connect to a computer and be remotely controlled using the optional AIAcompact software. This, software also enables you to acquire coloured partial discharge patterns as well as report and save screen-shots.,

Every AIAcompact comes with a built-in four-channel multiplexer, which enables you to switch between four input channels. Additionally, the buttons on the panel of the instrument enable you to directly select one of the four signal sources. As a result, the partial discharge signal and the voltage signal are split and can be selected separately. All settings, e.g., such as the input and display modes, are stored individually for each channel.

Standard features include:

Built-in four-channel multiplexer
External infrared synchronisation box IRS1B
Analogue gating for capturing disturbance signals via an external signal processing unit
Output for the connection of a paper recorder or similar instrument
Built-in speaker for the audible indication of detected PD signals
Available in three different housing options
Four possible ways of synchronising the instrument

FAQ / Frequently Asked Questions

Why are PD tests on gas-insulated switchgear and lines ( GIS/GIL) recommended?

Gas-insulated switchgear lines are of high importance for every grid: With high electric fields in comparatively small spaces, failure can lead to extensive damage and long outages. PD measurements with the AIAcompact can help to keep GIS/GIL units in service for longer through early identification of insulation defects, thereby preventing asset breakdowns and system failures.

What is the difference between acoustic and electric UHF PD measurements?

PD, due to free metal particles moving inside the chamber, loose contacts, floating potentials, or surface protrusions, causes electromagnetic waves in the ultra-high frequency (UHF) range, which propagate within the GIS/GIL structure. To detect the kinds of ‘“electric’” PD signals, UHF sensors can be attached to unshielded flanges or the surface of an inspection window. Alternatively, most modern GIS/GIL systems are manufactured with embedded UHF sensors. These sensors convert the electromagnetic wave of the PD to voltage, enabling the PD to be measured. Partial discharge activity also causes sound waves to propagate within the insulating SF6 gas and metallic structures of the GIS/GIL. Here, acoustic sensors are particularly useful at detecting the fault. They convert the sound wave of the PD to voltage, enabling the PD to be measured. Additionally, the AIAcompact reconverts the voltage to sound for an audible indication of detected PD signals via the built-in speaker or connected headphones.

What kind of information is useful to know before a PD measurement on GIS/GIL?

It is always useful to gather as much information as possible in advance. In particular, try to be informed about:

The reason for testing
The size of the GIS and its voltage level
The results of previous measurements and maintenance, SAT/FAT…
The types of embedded sensors and their connector types
The availability of unshielded flanges
The size of windows (window diameter, pitch circle diameter, screw size)
The age of the components to be tested

What kind of accessories are available for PD measurements on GIS/GIL?

Power Diagnostix offers a broad range of PD sensors, cables, and other accessories to cover most of the possible testing situations with a GIS/GIL system. Please refer to Power Diagnostix’s accessories catalogue for further information.

Troubleshooting

The AIAcompact doesn’t do anything when powered up

The power fuse might be blown. Unplug the unit and check the power supply fuse. This fuse is located on the rear panel of the AIAcompact (desktop and rack mountable version) or in the upper left corner (Explorer case version) above the on/off switch.

Another reason for this failure might be an empty battery. Check the battery level and recharge it if necessary.

If the battery is not the issue, please contact us at [email protected] to discuss the next troubleshooting steps.

The connected computer cannot find the AIAcompact

A communications error with the serial connection to the AIAcompact might have occurred. Within the AIAcompact PC software, check that the serial COM port selected in the menu “Options” > “Interface settings” is the COM port to which the AIAcompact is connected.

Within the Windows Device Manager, check if the USB driver was properly installed.

If this does not work, try rebooting both the AIAcompact and the PC.

The automatic installation of the USB driver fails

It’s possible to install the driver manually. Manual installation is divided into two steps due to the driver properties:

Step 1:

Open the Device Manager.
Select “Silicon Labs CP210X USB to UART Bridge”, which is listed as an item of “Other devices”.
Right-click on it and select “Update Driver” from the context menu.
The Hardware Update Wizard will open. Select “Search for the best driver in these locations”. and specify the directory where the AIAcompact software has been installed.
Click “NEXT” to proceed. Windows will now install the first part of the driver software which is the USB controller driver. Usually, the installation will end with an error message, as the second part of the driver – the USB bridge driver – will still be missing.

Step 2:

Repeat the steps above to install the second part of the CP210X bridge driver.
If the installation is completed successfully, the CP210X device should appear in the Device Manager.

The AIAcompact application window appears very small on high resolution monitors in Windows 10

On PCs running Windows 10 with the Creator's Update of 2017, the AIAcompact application window may appear very small on high resolution monitors. To enlarge the display size of the software, please take the following steps:

Right-click on the application shortcut on the desktop.
Choose "Properties" from the context menu, which will open the Properties window.
Enable "Override high DPI scaling behaviour" and set "Scaling performed by" to "System" on the "Compatibility" tab.
If you have administrator rights, you can change the settings for all users by clicking the corresponding button.
Approve the change by clicking “OK”.

The “RPA?” message appears in the lower left portion of the data display of the LCD panel, even though the preamplifier from Power Diagnostix is connected

The RPA might be installed improperly (backwards). Check that the BNC connector, marked with an incoming arrow, leads from the sensor, and that the BNC connector, marked by the outgoing arrow, leads to the BNC connector labelled “CHx” on the rear panel of the AIAcompact.

The preamplifier must be enabled if an RPA is connected. Ensure that “>AS+RPA” is marked in the “INPUT” menu of the instrument.

If this fails to resolve the issue, Try substituting the BNC cables to be sure that the problem is not in the cables themselves. Replace the cables if they are faulty.

If the cables are not the issue, please contact us at [email protected] to discuss the next troubleshooting steps.

The “AS?” message appears in the lower left portion of the data display of the LCD panel, even though the acoustic sensor from Power Diagnostix is connected

Acquisition via acoustic sensors must be enabled in the instrument menu. Ensure that “>AS” (or “>AS+RPA” if the sensor is used in combination with a preamplifier) is marked in the “INPUT” menu of the instrument.

If this fails to resolve the issue, try substituting the BNC cables to be sure that the problem is not in the cables themselves. Replace the cables if they are faulty.

If the cables are not the issue, please contact us at [email protected] to discuss the next troubleshooting steps.

Interpreting test results

Evaluation of phase-resolved partial discharge (PRPD) patterns

The evaluation of a PRPD pattern, enables you to determine the kind of fault within the test object. Most partial discharge (PD) faults such as insulation damages, voids, surface discharges, or floating points will have a completely different PD pattern. The typical criteria for classifying these patterns are:

Phase position of the maximum PD
Phase position of the starting electron
The gradient of discharges
The shape of discharges in the positive and negative half-cycle
The absolute value of discharge in pC or nC
Short-time or continuous discharges

For successful interpretation, it is also necessary to get as much information as possible about the test object and its environment. Such information can be, for example, temperature, installation condition, age of the test object, previous faults, or weather conditions.

It is useful to store typical PD patterns of known faults in an archive, which can be done by using Power Diagnostix’s AIAcompact software. This customer-specific database will be helpful for later evaluation on other test objects.

FAQ / Frequently Asked Questions

What can I do if environmental background noise hampers my measurement?

Depending on the level, nature, and source of the disturbing signals, the AIAcompact offers different options for noise handling. A noise level that is stable over the whole phase can be removed from the partial discharge (PD) pattern by the low level discriminator (LLD) function. Disturbances that always occur at the same phase position can be masked with the window function.In case the AIAcompact is used for partial discharge measurements in an environment with high frequency (HF) disturbance, such as radar signals, corona discharge, or a thyristor firing, the analogue gating function should be used. TherebyThis enables, the AIAcompact to beis connected to an external noise sensor, that picks up the disturbance signal. This signal is used for as an effective noise reduction reducer by blending out such impulse noise.

How can the AIAcompact be synchronized if no external voltage source is available?

For the acquisition of a PD pattern over more than one cycle, it is mandatory to synchronise the AIAcompact with (align phase with) the frequency of the specimen voltage, preferably by using an external signal source. If no such source is available, the AIAcompact allows three other ways for you to adjust the synchronisation: 1. Take the synchronisation signal from the power supply frequency of the mains connector. 2. Use the infra-red synchronisation signal that comes from the remote IRS1B box, which is included in the scope of delivery. 3. Use the synchronisation signal that is generated internally. Here, the last measured frequency is used.

How often should the AIAcompact be calibrated?

The AIAcompact does not need any calibration, nor does it require any maintenance on a regular basis.