Podcast
Questions and Answers
What is the primary function of bushings in transformers?
What is the primary function of bushings in transformers?
Which type of bushing is designed for voltages starting from 70 kV?
Which type of bushing is designed for voltages starting from 70 kV?
What is a key advantage of using graded bushings over non-graded bushings?
What is a key advantage of using graded bushings over non-graded bushings?
Which component is NOT part of a bushing's construction?
Which component is NOT part of a bushing's construction?
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What is a significant risk associated with Oil-Impregnated Paper (OIP) bushings?
What is a significant risk associated with Oil-Impregnated Paper (OIP) bushings?
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How does online monitoring of bushings improve health assessment?
How does online monitoring of bushings improve health assessment?
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What advantage do Resin-Impregnated Paper (RIP) bushings have over OIP bushings?
What advantage do Resin-Impregnated Paper (RIP) bushings have over OIP bushings?
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What is a limitation of offline measurements for bushing health assessment?
What is a limitation of offline measurements for bushing health assessment?
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What is the primary purpose of measuring capacitance in bushings?
What is the primary purpose of measuring capacitance in bushings?
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Why is the dissipation factor (tan Delta) considered complex and sensitive to external factors?
Why is the dissipation factor (tan Delta) considered complex and sensitive to external factors?
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What does the Bushing Coupling Unit (BCU) do in the EOS system?
What does the Bushing Coupling Unit (BCU) do in the EOS system?
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Which of the following factors is NOT crucial for ensuring accurate offline measurements?
Which of the following factors is NOT crucial for ensuring accurate offline measurements?
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What is a significant advantage of the Double Reference Method?
What is a significant advantage of the Double Reference Method?
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What is the role of the bushing adapter in the measurement system?
What is the role of the bushing adapter in the measurement system?
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What is an essential practice when installing bushing adapters?
What is an essential practice when installing bushing adapters?
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How does temperature influence capacitance measurements?
How does temperature influence capacitance measurements?
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What is the primary purpose of coupling units in transformer bushing monitoring?
What is the primary purpose of coupling units in transformer bushing monitoring?
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What is the recommended weight characteristic of bushing adapters?
What is the recommended weight characteristic of bushing adapters?
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In the setup process for bushing monitoring, what is the purpose of terminal arrays?
In the setup process for bushing monitoring, what is the purpose of terminal arrays?
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What action must operators take to acknowledge and clear alarms in the bushing monitoring system?
What action must operators take to acknowledge and clear alarms in the bushing monitoring system?
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Why is grounding important for Bushing Coupling Units (BCU)?
Why is grounding important for Bushing Coupling Units (BCU)?
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What is the default setting for alarm thresholds in the bushing monitoring system?
What is the default setting for alarm thresholds in the bushing monitoring system?
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What feature is integrated into coupling units to protect against overvoltage?
What feature is integrated into coupling units to protect against overvoltage?
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What does site acceptance testing (SAT) ensure in the context of bushing monitoring?
What does site acceptance testing (SAT) ensure in the context of bushing monitoring?
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What is a potential indication of cable faults or damage in the monitoring system?
What is a potential indication of cable faults or damage in the monitoring system?
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Study Notes
Session Overview
- Welcome to the fifth session of the live training series "Itos for Customers."
- Focus on embedded Transformer operating system (ITOS), particularly on bushing monitoring.
- Co-hosts are Florian Meer and Peter Shelter, both experienced in transformer technology.
Bushing Basics
- Bushings are necessary for leading high voltage and current through grounded barriers, such as transformer tanks.
- Two main types of bushings are commonly discussed: graded and non-graded.
- Graded bushings are used for voltages starting from 70 kV, incorporating capacitance layers for even dielectric field distribution.
Graded Bushings Explained
- Graded bushings feature capacitance layers that help ensure a homogeneous dielectric field.
- A visual simulation demonstrates the difference in electric field stress between graded and non-graded bushings, highlighting the benefits of graded insulation.
Bushing Construction
- Important parts of a bushing:
- Central conductor (aluminum).
- Insulation consisting of grading foils and impregnated paper.
- The measuring tab for capacitance measurement.
- Cut-open bushing examples illustrate internal structure and layer arrangement.
Technologies in Bushing Manufacturing
- Two primary technologies for bushings:
- Oil-Impregnated Paper (OIP) Bushings
- Contains oil, which aids insulation but poses fire and contamination risks.
- Common in distribution transformers.
- Resin-Impregnated Paper (RIP) Bushings
- Dry technology, more reliable and easier to store.
- Generally more expensive than OIP.
- Oil-Impregnated Paper (OIP) Bushings
Health Monitoring of Bushings
- Health assessment methods include:
- Offline Measurements: High accuracy, conducted every several years, but may miss rapid changes in condition.
- Online Monitoring: Continuous tracking of health, allowing for timely offline diagnostics when changes are detected.
Key Factors in Bushing Health
- Important measurements include:
- Capacitance: Indicates the health of the capacitive layers.
- Dissipation Factor: Measures insulation quality, changing gradually.
- Both measurements are essential, and values are often printed on the bushing's nameplate for easy reference.
Conclusion and Interaction
- Participants are encouraged to ask questions and share feedback via the chat, enhancing the interactive experience.
- Live transcription available for non-native English speakers to access captions in multiple languages.### Diagnostics Devices Overview
- Diagnostics devices are crucial for offline measurements, requiring transformer shutdown for accurate data.
- Offline diagnostics involve disconnected measurements, contrasting with online monitoring which operates during transformer function.
Online Monitoring System
- The EOS bushing monitoring system (msense BM) employs three primary components:
- Bushing Adapter: Directly connects to the bushing's test tap to detect voltage.
- Bushing Coupling Unit (BCU): Adapts voltage for measurement compatibility.
- Measuring Card: Analyzes data collected from the bushing to assess health.
Bushing Adapter Details
- Each adapter must fit various bushing types; features include different thread lengths and pin sizes.
- All adapters share a standardized connection style for consistency, but internal designs vary significantly among types.
- The connection to the measuring tap must be secure to avoid high voltage arcing.
Safety and Voltage Concerns
- Operating bushings without protective covers can create dangerous conditions, leading to potential equipment damage and safety risks.
- Adapters replace test tap covers and must be used when performing measurements to ground the bushing adequately.
Measurement Parameters
- Key measurements include capacitance and dissipation factor (tan Delta), both indicating bushing health.
- Capacitance is a primary monitoring target while tan Delta is reserved for critical applications due to its complexity and sensitivity to external factors.
Temperature Influence
- Capacitance and tan Delta values can significantly change with temperature fluctuations.
- Effective monitoring requires consideration of temperature impacts, using algorithms to mitigate errors introduced by fluctuating environmental conditions.
Double Reference Method
- This method compares neighboring bushings in a three-phase transformer system to neutralize the effects of environmental variables, enhancing measurement accuracy.
System Design and Benefits
- The EOS system eliminates the need for additional sensors outside the measurement setup, reducing possible error sources and false activations.
- Environmental influences, such as weather and operating conditions, are minimized to ensure accurate readings.
Bushing Adapter Installation
- The bushing adapter must be fastened onto the measuring tap correctly to ensure safety and precise measurements.
- Variations in bushing designs can necessitate different adapters even from the same manufacturer; information is gleaned from the nameplate data.
Coupling Unit Functionality
- The BCU establishes grounded resistance essential for accurate measurements, with capacitance tailored to specific bushing applications.
- System voltage, not just rated voltage, influences measurement setups in the design phase.
Hardware Components Summary
- Two generations of measuring cards exist, both providing accurate voltage measurements for analyses.
- Cabinet connections secure data flow from bushing adapters to the measuring card for effective monitoring.
Practical Considerations
- Recommended practices include following manufacturer torque specifications when securing adapters to ensure stable connections.
- Identification of proper bushing adapters requires manufacturers’ documentation, emphasizing the importance of nameplate details for compatibility.
Conclusion
- Understanding the components and their integration in the bushing monitoring process is essential for effective online diagnostics, ensuring transformer reliability and safety.### Coupling Unit Specifications
- Two coupling units discussed: one valued at 0.3 microfarads and another at 0.2 microfarads (200 nanopar).
- Proper coupling units maximize compatibility with transformers and their bushings.
- The separation of components (bushing adapter and coupling unit) prevents potential damage from vibrations during operation.
Installation Insights
- Lightweight bushing adapters (typically a few grams) are designed to minimize stress on the transformer’s bushing.
- Heavy coupling units must be securely mounted away from sensitive measuring taps to avoid damage.
- Grounding is crucial; Bushing Coupling Units (BCU) require proper connections for accurate voltage readings.
Setup Process
- Cables approximately 7m long facilitate the connection between the bushing coupling unit and monitoring systems.
- Includes specific connectors to prevent incorrect installations; only fits one way.
- Terminal arrays included in the setup allow for easy shielding and wiring of signals to measurement hardware.
Bushing Monitoring System
- The system's state is displayed on a computer interface with options to monitor and set parameters for bushing voltage and capacitance.
- Signals must be activated in the settings; initial capacitance values must be accurately preset based on manufacturer data.
- Default warning thresholds set at 5% for warnings and 10% for alarms, adjustable based on specific bushing characteristics.
Commissioning and Testing
- Site acceptance testing (SAT) is critical as factory acceptance tests may not replicate field conditions accurately.
- Real-time voltage monitoring renders immediate feedback about bushing status; events initiate alerts for issues like invalid measured voltage.
- Changes in operating voltage can be simulated to test system responses and validate warning and alarm thresholds.
Event Management
- Active acknowledgments are necessary to clear alarms in the system interface, ensuring operators are aware and responsible for any issues.
- System automatically detects any drops in signal inputs, indicating potential cable faults or damage immediately.
Safety Features
- Gas discharge tubes are integrated into coupling units for redundancy and protection against overvoltage; they connect internally to monitor voltage without damage.
- The design of the coupling units aims to ensure long-term operational safety and integrity in monitoring applications.
Session Overview
- Fifth session of "Itos for Customers," emphasizing the embedded Transformer operating system (ITOS) and bushing monitoring.
- Co-hosts Florian Meer and Peter Shelter bring expertise in transformer technology.
Bushing Basics
- Bushings crucial for transmitting high voltage/current through grounded barriers like transformer tanks.
- Two primary bushing types: graded (for 70 kV and above) and non-graded.
Graded Bushings Explained
- Graded bushings incorporate capacitance layers for a uniform dielectric field distribution.
- Visual simulations show reduced electric field stress in graded bushings compared to non-graded.
Bushing Construction
- Components include:
- Central conductor (aluminum).
- Insulation with grading foils and impregnated paper.
- Measuring tab for capacitance assessment.
- Cut-open examples illustrate the bushing's internal structure.
Technologies in Bushing Manufacturing
- Oil-Impregnated Paper (OIP) Bushings:
- Contains oil for insulation, with fire and contamination risks.
- Commonly used in distribution transformers.
- Resin-Impregnated Paper (RIP) Bushings:
- Employs a dry technology, more reliable and easier to store but generally pricier than OIP.
Health Monitoring of Bushings
- Health assessment methods:
- Offline Measurements: High accuracy, periodic checks but may overlook rapid condition changes.
- Online Monitoring: Continuous evaluation for timely offline diagnostics.
Key Factors in Bushing Health
- Critical measurements:
- Capacitance: Indicates health of capacitive layers.
- Dissipation Factor: Insulation quality metric, changes gradually.
- Values are typically displayed on the bushing nameplate for reference.
Conclusion and Interaction
- Participants encouraged to engage via chat for questions and feedback.
- Live transcription for non-native speakers available in multiple languages.
Diagnostics Devices Overview
- Essential for offline measurements, which require the transformer to be shut down.
- Offline diagnostics differ from real-time online monitoring.
Online Monitoring System
- EOS bushing monitoring system (msense BM) consists of:
- Bushing Adapter: Connects to bushing's test tap.
- Bushing Coupling Unit (BCU): Adjusts voltage for compatibility in measurements.
- Measuring Card: Analyzes data to assess bushing health.
Bushing Adapter Details
- Adapters designed for various bushing types, with standardized connection and unique internal designs.
- Secure connections to measuring taps are essential to prevent arcing.
Safety and Voltage Concerns
- Operating bushings without protective covers risks equipment damage and safety hazards.
- Adapters serve to ground the bushing during use.
Measurement Parameters
- Key measurements: capacitance and dissipation factor (tan Delta); important for assessing bushing health.
- Capacitance is a primary focus; tan Delta is reserved for critical applications due to sensitivity.
Temperature Influence
- Values of capacitance and tan Delta vary with temperature changes.
- Monitoring must adjust for temperature variations to reduce error.
Double Reference Method
- Compares neighboring bushings in three-phase systems to negate environmental influence on measurement accuracy.
System Design and Benefits
- EOS system minimizes external sensor requirements, reducing error potential.
- Environmental factors are controlled for accurate readings.
Bushing Adapter Installation
- Correct fastening of adapters to measuring taps is vital for safety and measurement accuracy.
- Different bushing designs may need unique adapters; refer to nameplate data for compatibility.
Coupling Unit Functionality
- BCU provides grounded resistance essential for precise measurement setup.
- Measurement configurations consider system voltage over just rated voltage.
Hardware Components Summary
- Two generations of measuring cards ensure accurate voltage assessment.
- Cabinet connections facilitate effective data transfer from adapters to measuring cards.
Practical Considerations
- Adhere to manufacturer torque specifications to maintain stable connections during installation.
- Proper identification of bushing adapters relies on documentation from the manufacturer.
Conclusion
- Understanding the integration of components in bushing monitoring is key to ensuring transformer reliability and safety.
Coupling Unit Specifications
- Discussed coupling units valued at 0.3 microfarads and 0.2 microfarads, optimizing transformer compatibility.
- Separation of bushing adapter and coupling unit helps prevent damage due to vibrations.
Installation Insights
- Lightweight bushing adapters aim to reduce stress on bushings.
- Heavy coupling units should be securely mounted away from sensitive components to avoid damage.
- Proper grounding connections are vital for accurate voltage measurements of BCUs.
Setup Process
- Cables (approximately 7m long) connect BCU to monitoring systems.
- Specific connectors prevent incorrect installations, fitting only one way.
Bushing Monitoring System
- Displays system state on a computer interface, with options for monitoring parameters.
- Initial capacitance values based on manufacturer data must be preset; default warning thresholds are adjustable.
Commissioning and Testing
- Site acceptance testing (SAT) essential; field conditions may differ from factory tests.
- Immediate feedback through real-time voltage monitoring for bushing status and alerts for issues.
Event Management
- System requires active acknowledgment of alarms; operators must be informed of issues.
- Automatic detection of signal input drops indicates cable faults.
Safety Features
- Gas discharge tubes in coupling units enhance protection against overvoltage.
- Internal connections monitor voltage to ensure long-term operational safety in monitoring setups.
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Description
Join us for the fifth session of the 'Itos for Customers' series, as we delve into the intricacies of bushing monitoring within embedded Transformer Operating Systems (ITOS). Co-hosts Florian Meer and Peter Shelter will guide you through the fundamentals of graded and non-graded bushings, exploring their construction and application in transformer technology.
