GISmonitor Portable portable partial discharge monitor

Power Diagnostix’s GISmonitor Portable offers parallel real-time PD measurements on up to 40 channels

The GISmonitor Portable is a portable instrument for the temporary monitoring of partial discharge activity on gas-insulated switchgear.

Partial discharge monitoring on demand

Real-time PD acquisition and analysis

Prevention of asset breakdowns and system failures by early identification of insulation defects

Available in four housing versions

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About the product

Power Diagnostix’s GISmonitor Portable is a portable instrument for the temporary monitoring of partial discharge activity on gas-insulated switchgears (GIS) caused by hopping particles, floating potentials, cracks in insulators or spacers, or other degradation in the insulation system. The instrument offers parallel real-time PD acquisition on up to 40 channels and any UHF signal can be detected and digitised within microseconds.

To eliminate disturbance signals from the measurement, the GISmonitor Portable can also be connected to a disturbance antenna that provides a gating signaI. This allows the instrument to separate PD events from external disturbances in real time, providing effective PD detection.

In addition, to ensure that your instrument provides reliable and precise results of the system under all harsh environmental or weather conditions, it is advisable to use the protective housing of the ICMoutlander.

The GISmonitor is designed to suit all common UHF sensors for GIS PD monitoring. This includes embedded and external retrofit UHF sensors. A special input protection unit (IPU2) blocks strong transients. The frequency converter unit FCU2 demodulates UHF signals into a lower frequency band for easy submission over longer distances.

The instrument can be connected to a PC or laptop via a USB port or an optional LAN interface for data evaluation and in-depth diagnosis with the GISmonitor Portable software. This service software provides easy access to view, compare, and analyse the acquired data. The current readings of up to 24 partial discharge sensors of a GIS are visualised in parallel. Each sensor is linked with a specific input channel of the GISmonitor.

In addition to the standard acquisition of partial discharge versus phase position, the GISmonitor Portable software gives you the ability to acquire partial discharge at DC voltage. In this mode, the partial discharge pulses are displayed against time.

Every version of the GISmonitor Portable can also be used with the software of the non-portable GISmonitor system.

To receive software updates or user guides, please contact [email protected] or call +49 241 74927. Please have your device serial number ready or state your reason for interest.

FAQ / Frequently Asked Questions

Why is temporary PD monitoring on GIS/GIL recommended?

Gas-insulated switchgear/line is of high importance for every grid: With high electric fields in comparatively small spaces, failure can lead to extensive damage and long outages. Temporary PD monitoring with the GISmonitor Portable can help to keep GIS/GIL units in service for longer by early identification of insulation defects and, thus, prevention of asset breakdowns and system failures.

What kind of information is useful to know before temporary PD monitoring 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 monitoring
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

Is there a way to reduce disturbance signals during partial discharge measurements?

An effective noise reduction is required in case that measurements are taken in an environment with ultra high frequency (UHF) disturbance, such as disturbances created by cell phones, corona effects, or similar, because these disturbances can hamper the partial discharge detection. The GISmonitor Portable uses a gating signal picked up by a disturbance antenna, which is used to blind out the disturbances during the measurement.General background noise can be handled by setting a low level discriminator (LLD) in the control software.

Troubleshooting

The GISmonitor 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 GISmonitor (desktop version) or in the upper left corner (Explorer case version) above the on/off switch.

The software cannot find the GISmonitor Portable with a USB connection

Check the device settings in the software. The connection type must be set to “USB”.

The software cannot find the GISmonitor Portable with a LAN connection

Check the device settings in the software. The connection type must be set to “LAN”, and the correct IP address of the connected instrument must be provided.

Check if, the IP address of your PC is set to the same IP range as the one on your instrument.

The software’s overview schematic shows a flashing orange frame around a sensor

A flashing orange frame indicates a lost connection between the GISmonitor and a frequency converter unit (FCU). Please check the connection cable and make sure the FCU is working correctly.

There is no signal visible on one or more of the channels

Check the range and the low level discriminator (LLD) settings in the software.

I get too many false alarms and warnings from the software

Try to adjust the corresponding alert threshold. If this does not lead to any improvement, check if disturbances or background noise are hampering the partial discharge measurement leading to false alarms. If so, try to adjust the low level discriminator (LLD) or use a gating antenna and the GISmonitor’s gating function to blend out the unwanted signals.

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 faults, such as insulation damages, voids, surface discharges, or floating points, will have completely different partial discharge patterns.

These are the typical criteria for classifying these patterns:

Phase position of the maximum partial discharge
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 the software for the GISmonitor Portable. This customer-specific database will be helpful for later evaluation on other test objects.

User guides and documents

User guide

GISmon_sw_man_en.pdf

pdf 2.14 MB

User guide

ICMoutlander_man_en.pdf

pdf 5.85 MB

Technical guide

PD Interview with the Experts_excerpt_ET_Mag_Issue_2_V01_DIG.pdf

pdf 1.51 MB

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 GISmonitor Portable 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 using the low level discriminator (LLD) function. In case the GISmonitor Portable is used for PD measurements in an environment with high frequency (HF) disturbance, such as radar signals, corona discharge, or thyristor firing, the analogue gating function should be used. The GISmonitor Portable is connected to an external noise sensor, that picks up the disturbance signal. This signal is used as an effective noise reducer by blending out the impulse noise.

Is an external synchronization source mandatory?

Often, the high voltage applied to the test setup is not in phase with the line voltage and may not even be the same frequency as the line voltage. In such cases, it is best to synchronize the GISmonitor Portable with an external signal. Nevertheless, in the absence of an external synchronization signal, the GISmonitor Portable can be configured to synchronize with the sine wave of the line voltage of the GISmonitor Portable’s supplying power. Therefore, an external synchronization signal is not mandatory but recommended.

How often should the GISmonitor Portable be calibrated?

The GISmonitor Portable does not need any calibration, nor does it require any maintenance on a regular basis. However, if the instrument is used for a sensitivity verification, the used impulse generator as the reference source should be calibrated on an annual basis to ensure that its output signal remains within the recommended boundaries.

What kind of accessories are available for PD monitoring 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.