siemens.co.uk/assetguard

Gas insulated switchgear (GIS) has been found to be ideally suited to the power transmission industry’s need for switchgear that features a small footprint and offers the utmost reliability, with very low noise and electromagnetic emissions. It guarantees the safety, reliability and continuity of the power supply and protects your premises from the consequences of failure. However, GIS can be subject to partial discharge (PD), a minute breakdown of the switchgear insulation, which can be an indication of the insulation’s deterioration, or of other defects in the GIS.

So how can you safeguard the reliability of the switchgear? With ageing equipment now working at ever higher levels of demand, it is essential to be able to monitor and forecast the health and remaining life of your switchgear assets and determine whether to overhaul and refurbish existing equipment; retrofit and upgrade it, or simply replace it. The Assetguard range from Siemens is a solution to this industry problem.

The Assetguard rangeA dictionary definition of “to be on guard” is to be in “a state of vigilance or preparedness against adverse circumstances”. We couldn’t put it better. Assetguard solutions enable you to be truly vigilant at all times. For partial discharge monitoring, the Assetguard Partial Discharge Monitoring System (Assetguard PDM) is a rational choice.

Partial discharge monitoringWith the largest installed base of GIS in the UK, Siemens has a proven track record in this field. Irrespective of manufacturer, it makes sound business sense to ‘sweat

the assets’: maximise the life of valuable switchgear and gain maximum benefit from it too. Assetguard PDM provides the user with a performance and quality tool during both the commissioning phase and lifetime of the substation, supporting:

¡ In-service periodic monitoring ¡ Continuous monitoring and trend analysis ¡ ‘End-of-life’ assessment via its historical database.

It allows the user to assess the integrity (quality) of the substation primary insulation during high voltage (HV) test or operation. The online system acquires and diagnoses data from active ultra-high frequency (UHF) signals that may be generated within the GIS – hence, it provides an early warning system for any deterioration problems.

Specialised measurements and diagnosticsAssetguard PDM can detect partial discharge at early stages by monitoring and diagnosing the buildup of signal activity to avoid serious incidents occurring. Utilising pre-installed UHF sensors or fitting external UHF sensors, the system can locate the signal and diagnose the nature of the defect. Detection of PD activity on substations of 66kV and above will enable the user to reduce HV test commissioning time.

Each node unit is capable of processing data for 48 UHF inputs. Typically, this allows one Node (processing point) to process data for up to four GIS Switchgear bays. It is also possible to perform Partial Discharge localisation, with the application of a Siemens portable diagnostics & location (DiaLoc) system. Data can be viewed in real-time instantaneous displays on screen.

The Siemens Assetguard range: Partial Discharge Monitoring Safeguarding the reliability of gas-insulated switchgear

Energy Management

The Assetguard range

Siemens’ Assetguard range of applications is the basis of our Integrated Substation Condition Monitoring (ISCM®) system, covering all primary equipment including HV and MV switchgear and transformers.

Assetguard supports partial discharge detection measurements, circuit breaker monitoring and SF6 gas density monitoring, with both GIS and AIS switchgear: from 66kV and above. Its modular design is easily implemented in an existing substation infrastructure and extended to further assets if needed.

Moreover, to assist with analysis of the data generated, Siemens’ complementary, dynamic Reliability Centred Asset Management tool, RCAM® Dynamic, will take the data from Assetguard and produce a health index for every asset within an electrical grid.

It all adds up to a truly integrated approach.

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The diagnostics are carried out as the signals are detected, second- by-second. This allows for noise and PD segregation; ensuring that spurious alarms are minimised or eliminated and also incorporating noise gating technology (Figure 1).

The system supports compliance with IEC requirements for high-voltage test techniques: partial discharge monitoring (CEI/IEC 60270:2000).

Alarms PD files are analysed and if the PD activity level exceeds the threshold for that particular coupler, then alarm analysis is carried out. The severity of the alarm is indicated on a three stage basis, yellow, orange or red:

¡ Yellow Alarm: Warning (a low level PD signal has been detected)

¡ Orange Alarm: Failure (PD is significant)

¡ Red Alarm: Critical (either from an instantaneous PD signal or building upon the two previous alarms).

The alarm screen enables the user to view current and previous alarm data

in the form of trend plots. Time periods are selected which allow alarms activated by parameters breaching their limits to be easily identified within the defined timescale. Operators can then further analyse the data, with multiple options available for sensor comparison and pattern recognition.

Location UHF sensors are connected via UHF cables to Assetguard PDM Opto Detector Units, which can each monitor three sensor inputs. These are connected via a special Siemens hybrid cable to PDM Nodes, which house the data acquisition and facilities; and from there to a central ISCM Control Cubicle, where alarm data is automatically generated. Multiple opto-detector units can be connected to provide adequate coverage for every size of GIS substation.

Benefits at a glance Assetguard PDM will help you achieve distinct and measurable benefits:

¡ Expert screens to diagnose contamination and swiftly evaluate switchgear performance

¡ Mitigation of the risks of failure of the system

¡ Fewer unexpected outages through improved failure detection

¡ Shutdown times scheduled to fit with a proactive rather than reactive maintenance strategy

¡ Lower cost as repair work is more easily planned

¡ Condition-based maintenance based on real operational stress parameters

¡ Technology that works with both new and retrofit GIS substations.

Finally, ISCM® brings true integration: a platform where multiple applications can be hosted, monitoring switchgear, transformers and other primary equipment.

How can we help you? Siemens has been involved in the field of switchgear condition monitoring for over 25 years and in manufacturing solutions for the industry for over 45 years. For further information on how we can help you safeguard the reliability and continuity of your operations, or to request more detailed technical information on the Assetguard range, please contact us.

(Figure 1)