ABB EXCOUNT-III Surge Counters | Remote & Real Monitoring of High Voltage Power Systems
Published 15 Sep 2022
Protection of MV HV Medium High Voltage Cables & Power Systems
ABB introduces the next generation of monitoring equipment for surge arresters: EXCOUNT-III, utilising unique features previously unseen on the market.
Interest for online surge arrester monitoring is growing, and so the EXCOUNT-III Surge Counters have been designed to fulfil this need by providing the user with remote real-time monitoring of arresters as well as useful input to the insulation co-ordination of the station as a whole.
What are Surge Counters?
Surge Counters are used to monitor the health of Surge Arresters and protect against potentially damaging events which could lead to deterioration and ultimate overload. It is important to also schedule regular checks of surge arresters including visual inspection and diagnostics to detect and prevent a costly power outage.
The EXCOUNT surge counter range draws upon over 70 years of experience by ABB in the development of arresters and associated accessories. Safety, functionality and longevity are key elements which are given priority in selection and design of components. In stark contrast to many other competing products, the EXCOUNT surge counters has not neglected short-circuit safety which lies inherent in the design concept.
With market pressure on utilities to obtain near 100% power availability, taking all actions to avoid even a rare unplanned outage is vital. As users push their systems harder accordingly, it can be expected to see stresses from system events leading to the arresters also being called upon to act more often than they perhaps did in the past. Monitoring how they handle those stresses – as well as what the consequences of those events are on the system itself – may be included as part of the user’s strategy for improving the overall availability. EXCOUNT-III has been developed with this strategy in mind.
EXCOUNT-III is a complete remote real-time surge arrester monitoring, diagnostics and analysis system. It permits the registration of the total number of discharges, the surge amplitude and wave-steepness, the date and time of occurrence, the total leakage current as well as the resistive leakage current through the surge arrester. In addition, the equipment can be used to define the residual voltage across the arrester for the actual surge, which in turn can be used to better estimate overvoltages in the station for a more detailed insulation co-ordination evaluation.
Not only does the EXCOUNT monitor the arrester itself, it can also give an estimate of overvoltage occurring at nearby apparatus within the arrester’s protection zone – providing valuable information about whether the protection against potentially damaging surges is sufficient or not. In this way, EXCOUNT-III provides the user with remote real-time monitoring of arresters as well as useful input to the insulation co-ordination of the station as a whole.
ABB EXCOUNT-III surge counter supports the protocol IEC 61850, Ed. 2, and communicates remotely via the fibre optic cable to permit the user to add signals into an existing data collection system (SCADA). Enabling remote retrieval of data, EXCOUNT-III eliminates the need for substation visits solely to monitor surge arrester condition, while also enabling the highest possible personnel safety standard by not having to approach an energized arrester to perform online diagnostic measurements.
Excount-III Applications & Performance Data
The EXCOUNT-III system consists of individual sensors that are connected by an optical fibre connection. Each sensor can be interrogated individually and be integrated to existing SCADA system. For use with all makes and types of gapless arresters.
- No voltage added to the residual voltage of the arrester
- Complete monitoring of the health of the substation and the surge arresters
- Remote real-time monitoring – minimizes substation visits and enables the highest possible personnel safety standard
- Supports IEC 61850, Ed. 2, for integration to existing SCADA system
- Enables analysis of surge current impulses
- Estimation of overvoltages in the station allows for a more detailed insulation co-ordination evaluation
- Simple to use
- Maintenance free
For each surge arrester it is fitted on, the advanced version (EXCOUNT-IIIA) registers the total number of discharges, the surge amplitude and wave-steepness, the date and time of occurrence, the total leakage current as well as the resistive leakage current through the arrester by thirdharmonic analysis (method B2 according to IEC 60099-5). Using high speed sampling and sweep time, complete surge current impulses at the arrester’s connection point are recorded and available for analysis.
The standard version (EXCOUNT-IIIM) is available for users who do not desire to analyse the overvoltages in detail. With this, discharges are only categorized by their amplitude along with a date and time stamp of occurrence. Other generic features are the same between the versions.
A web browser interface via an optical fibre connection permits online interrogation and data analysis from each unit individually and is also used for configuration setup. The introduction of smart grid and the communication protocol IEC 61850 has made users more focused on integration with existing SCADA systems. EXCOUNT-III supports this protocol and communicates remotely via the fibre optic cable to permit the user to add signals into an existing data collection system.
In addition to surge counting, a special feature of the advanced version is the registration of the surge amplitude and wave-steepness. This can be used to define the residual voltage across the arrester for the actual surge, which in turn can be used to better estimate overvoltages in the station for a more detailed evaluation of insulation coordination than has been possible in the past.
This added-value feature will help users to verify if they have adequate protection or if they need to reconsider their choice of arrester or even increase the number of arresters in the station. Furthermore, there is particular interest to correlate front time and overvoltage levels with pre-existing transformer monitoring equipment as a means to support total system condition monitoring diagnostics.
Leakage current measurement and condition
EXCOUNT-III gives the user the possibility to measure both the total leakage current as well as the resistive component of the current through the arrester. The measurement of the resistive current especially gives a good indication of the arrester’s condition and fitness for continued service. With the aid of the SCADA system, these measurements can readily be used to co-ordinate maintenance work and possible replacement in order to assist with minimizing unnecessary and costly unplanned outages.
Safe and secure
EXCOUNT-III remote retrieval of data via the optical fibre cable eliminates the need for substation visits solely to monitor arrester condition, while also enabling the highest possible personnel safety standard by not having to approach an energized arrester to perform online diagnostic measurements. All components are housed in a sealed, weather-proof case, suitable for outdoor use. The base unit is mounted on the support structure and interconnected similar to a traditional counter, while the separate field probe is fixed at the bottom of the arrester. An external power connection from the station auxiliary supply (100 – 250 V, AC or DC) as well as a fibre optic cable connection are additionally to be provided by the user.
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