- Install Integrated Substation Condition Monitoring equipment to 96 11kV circuit breaker panels at seven Northern Powergrid primary sites.
- Collate data from installed equipment to a central server for a period of two years from the installation of equipment at the last site.
- Establish appropriate thresholds for alarm signals.
- Undertake analysis of the data periodically throughout the project to identify any correlation between variables or trends in circuit breaker performance.
Benefits
The project success criteria are defined as follows:
- Successful installation of circuit breaker condition monitoring equipment and partial discharge monitoring equipment at 7 substations with a total of 96 panels
- Successful collation of data from installed equipment
- Production of asset performance reports to inform Maintenance Policy and asset replacement/refurbishment decisions
- Initiation of remedial work or other intervention to improve circuit breaker performance
- Improvement of circuit breaker performance in relation to Failure on Demand, slow opening, etc.
- Prevention of an incident relating to circuit breaker failure by triggering intervention
- Trending of partial discharge for specific circuit breakers and circuit breaker by manufacturer and type
- Establish appropriate alarm thresholds for each circuit breaker type
- Demonstrate trends in dc trip coil profile for specific circuit breakers and circuit breaker by manufacturer and type
- Establish acceptable profile envelope for each circuit breaker type
- Trigger post fault maintenance by I2t measurements
- Demonstrate the relationship between environmental operating conditions and the level of partial discharge activity
- Demonstrate the relationship between environmental operating conditions and dc trip coil profile
Learnings
Outcomes
One of the challenges of monitoring circuit breaker trip performance is that the circuit breaker my not be called upon for several years and therefore it may take significant time to build up sufficient information to establish the reliability of an individual circuit breaker. If monitoring is applied to sufficient sample sizes of circuit breakers of specific types, it may be possible to establish the reliability of types in relation to each other, but this will not identify specific candidates to put forward for replacement.
The monitoring of partial discharge activity on switchboards during the trial has triggered alarms which were followed up with Technical Services and have subsequently been investigated further. The components that caused the relatively high levels of partial discharge are Reyrolle LMT1 CTs which have a history of high partial discharge that appears to be benign as the levels are stable, indicating no further deterioration. The challenge for partial discharge monitoring is that it is difficult to establish a definitive pass/fail threshold; each event needs to be investigated to identify the likely source and determine if it is associated with the deterioration of insulation, or a void in insulation that has been present since manufacture.
The monitoring of circuit breakers can provide valuable information to support maintenance and asset replacement programmes, but the low number of trip events and interpretation of partial discharge measurements required does not allow candidates for replacement to be identified in a timely and consistent manner.
The data acquisition stage of the project is still underway; it is intended that analysis of data will be undertaken over the next 24 months. This will help determine which data sources provide the most useful information and inform how we can reduce the volume of data that is collected in future.
The perceived technology readiness level at the outset was 8 and this was predicted to increase to 9 following completion of the project. This prediction is assessed to be relatively accurate, notwithstanding the long delivery time during which technology has advanced.
Lessons Learnt
Key Lessons associated with milestone delivery
- Ensuring data communications from sensor equipment to reporting hub are placed as a critical path activity.
- Monitoring solutions to be non-intrusive to enable installation & commissioning without outage.
- Availability and management of scarce resources.
Key Lessons associated with project delivery methodology
- The benefits of co-creation were only partly realised on an ad-hoc basis between NPg, Siemens and third parties.
- Utilise co-location/co-creation project concept throughout the supply chain – eg. embed cross functional resources (policy, standards, commercial, domain & IT experts) into customers premises, use modern Agile project approaches.
- Technology approaches are superseded with the speed of change in the digital world – speed of implementation is critical.
Key Lessons from NPg Perspective
- Managing outage availability and SAP resource.
- Working within an access restriction affecting one particular site.
- Not to underestimate the potential impact of asbestos surveys and any mitigation or remedial work required.
- Anticipate broadband connection delays due to wayleave issues.
Give early consideration to internet security and accessing VPN via the mobile network.
