Shielding or corona rings are important in high-voltage systems. They stop corona discharges that harm equipment and waste energy. These rings spread out the electric field evenly. This keeps the field’s peak below the corona limit. For instance, changing the pipe size of a ring can raise the corona start voltage by 20.8%. Also, the curve’s radius can boost the stopping voltage by 30.3%. These qualities make shielding rings key for keeping HV systems safe and reliable.
Key Takeaways
- Shielding rings stop corona discharges by spreading electric fields evenly. This protects equipment and saves energy.
- These rings make insulators last longer by lowering stress from strong electric fields. This reduces maintenance costs.
- There are different shielding rings, like arrester and lightning rings. Each has a special use in high-voltage systems.
- Using shielding rings makes high-voltage systems work better and safer.
- Shielding rings are made of strong materials like aluminum and stainless steel. These materials work well in tough conditions.
Purpose of Shielding or Corona Rings
Shielding or corona rings are vital in high voltage systems. They help keep electrical equipment safe and working well. Below are their main purposes.
Stopping Corona Discharges
Corona discharges happen when the electric field gets too strong. This makes the air around a conductor ionize. It can waste energy, make noise, and harm equipment. Shielding rings stop this by spreading out the electric field. They lower the field’s strength to stay below the corona limit. This is especially useful in very high voltage systems. These systems have a higher chance of corona discharges. Using corona rings protects equipment and keeps things running smoothly.
Making Insulators Last Longer
Insulators face strong electric fields that can wear them out. Corona discharges make this wear happen faster. Shielding rings fix this by spreading the electric field evenly. This lowers stress on insulators and stops corona damage. Studies show shielding rings can help insulators last much longer. They are a smart way to save money and maintain high voltage systems.
- Benefits of shielding rings for insulators:
- Spread out the electric field evenly.
- Keep the electric field below the corona limit.
- Stop corona damage to insulators.
Keeping High Voltage Systems Reliable
High voltage systems need to work without problems. Corona discharges can cause energy loss and damage equipment. Shielding rings, like bushing shields, stop these discharges. They also save energy and improve system efficiency. This makes shielding rings essential for modern electrical systems.
By learning about shielding rings, you see why they matter. They stop corona discharges, protect insulators, and keep systems reliable.
Types of Shielding Rings
Shielding rings come in different types for various uses. Knowing these types helps you pick the right one. Below are three common kinds of corona rings.
Arrester Corona Rings
Arrester corona rings protect surge arresters from harmful electric discharges. They spread the electric field evenly around the arrester. This lowers stress and prevents damage to its surface. These rings help the arrester last longer. You often see them in high-voltage tests and power systems. They are made of lightweight aluminum alloy, making them easy to use.
Lightning Protection Corona Rings
Lightning protection corona rings guard systems from lightning surges. They are used in power lines to stop corona discharges. These rings surround insulators and lower the electric field’s strength. This keeps systems working reliably during lightning strikes. The table below compares corona rings and grading rings, which are used in similar ways:
| Feature | Corona Rings | Grading Rings |
|---|---|---|
| Material | Aluminum alloy | Aluminum alloy or galvanized steel |
| Purpose | Used in high-voltage test equipment | Surround insulators in high-voltage systems |
| Operational Context | Found in power systems | Found in power transmission lines |
| Installation | Quick and simple to install | Quick and simple to install |
This table shows corona rings are great for lightning protection. Grading rings, however, have broader uses.
Insulator Corona Rings
Insulator corona rings shield insulators from harmful electric discharges. They spread the electric field around the insulator evenly. This reduces stress and stops damage from happening. Using these rings can make insulators last much longer. They are important for keeping power lines and systems reliable.
Transformer Corona Rings
Transformer corona rings help protect high-voltage transformers. They spread the electric field evenly around the transformer. This stops harmful corona discharges that could damage the transformer. These rings are often used in systems with high-voltage transformers. Their design helps transformers work better and last longer.
Using these rings lowers the chance of energy loss or damage. They are made from strong materials like aluminum or stainless steel. Their lightweight build makes them easy to install. If you handle high-voltage transformers, adding these rings improves safety and reliability.
High Voltage Test Equipment Corona Rings
High voltage test equipment corona rings make testing safer. They control the electric field during tests. This stops corona discharges, protects equipment, and gives accurate results. These rings are a must for high-voltage testing.
You’ll see these rings in labs and testing centers. They are made for precision and strength. Aluminum alloy is often used to handle high stress. Adding these rings to your tests improves accuracy and keeps equipment working longer.
Power Transmission Line Corona Rings
Power transmission line corona rings keep systems efficient. They surround insulators and spread the electric field evenly. This stops corona discharges that waste energy and harm insulators. These rings are key for smooth power transmission.
They are built to handle tough outdoor conditions. They resist rust and stay effective over time. Adding these rings lowers repair costs and boosts system reliability. They protect insulators and save energy, making them essential for power systems today.
Functionality and Mechanism of Shielding Rings
Spreading Out the Electric Field
Shielding rings help control the electric field in high voltage systems. High voltage can make the electric field gather at sharp edges. This uneven field can cause corona, wasting energy and harming equipment. Corona rings spread the electric field evenly on the conductor’s surface. This reduces corona risk and helps the system work better.
For example, in surge arresters, shielding rings balance the electric field. This protects the equipment from damage. In bushing shields, the rings stop the field from gathering at certain spots. This prevents harm to the bushing. These features make shielding rings very important for high voltage systems.
Reducing Strong Electric Fields
High electric fields can cause corona discharge if too strong. Corona rings lower these strong fields by changing the conductor’s shape. A larger curve reduces the field’s strength at any one spot. This keeps the field below the corona limit.
For example, in extra high voltage (EHV) systems, corona rings are a must. They stop the electric field from becoming too strong. This keeps equipment safe and lasting longer. By lowering strong fields, shielding rings also save energy and improve system performance.
Stopping Corona Discharge Problems
Corona discharge wastes energy, makes noise, and harms equipment. Shielding rings stop this by controlling the electric field. They keep the field below the air’s ionization level. This is especially useful in high voltage testing, where accuracy matters.
Corona rings also protect insulators and other parts from damage. For example, in high voltage systems, they shield insulators from corona harm. This helps insulators last longer. These features are key for keeping high voltage systems reliable and efficient.
Shielding rings are vital for high voltage systems. They spread out the electric field, reduce strong fields, and stop corona problems. This ensures safety and better system performance.
Mechanism of Corona Discharge Prevention
Shielding rings are crucial for stopping corona discharge. To understand their role, you must know what corona discharge is and why it occurs. When the electric field near a conductor becomes too strong, air molecules ionize. This causes a glow, energy loss, and possible equipment damage. Shielding rings stop this by managing the electric field in several ways.
1. Smoothing Sharp Edges
Sharp edges on conductors create strong electric field spots. These “hot spots” often cause corona discharge. Shielding rings fix this by having a smooth, round shape. Their circular design spreads the electric field evenly, lowering its strength at any one spot.
Tip: Imagine water flowing over a smooth stone versus a jagged one. The smooth stone lets water flow evenly, while the jagged one creates splashes. Shielding rings work similarly for electric fields.
2. Increasing the Radius of Curvature
The radius of curvature shows how curved a surface is. A bigger radius means a gentler curve, which weakens the electric field. Shielding rings increase this radius around high-voltage equipment. This keeps the electric field below the air’s ionization level. A small change like this can greatly reduce corona discharge.
3. Distributing the Electric Field
Shielding rings act as buffers for the electric field. Instead of letting the field gather in one spot, they spread it out. This lowers the risk of ionization and protects nearby parts. For example, in transformers, the ring stops the electric field from harming insulation or other parts.
| Key Benefit | How It Works |
|---|---|
| Reduces field strength | Spreads the electric field evenly across the ring’s surface. |
| Prevents ionization | Keeps the electric field below the air’s ionization threshold. |
| Protects equipment | Shields insulators, transformers, and other components from corona damage. |
4. Minimizing Energy Loss
Corona discharge wastes energy as heat, light, and sound. Shielding rings stop this waste by preventing the discharge. This saves energy and makes the system more efficient. High-voltage transmission lines benefit most, as small losses add up over time.
5. Enhancing System Reliability
Shielding rings protect equipment from long-term damage by stopping corona discharge. They reduce wear on insulators, bushings, and other parts. This means fewer repairs, lower costs, and a more reliable system overall.
Note: A high-voltage system with shielding rings can last longer. It saves money and works efficiently for many years.
Specifications of Shielding Rings
Materials (Aluminum, Stainless Steel, Copper)
Shielding rings are made from strong materials like aluminum, stainless steel, and copper. Aluminum is light and conducts electricity well, making it easy to install. Stainless steel is tough and resists rust, perfect for outdoor use. Copper conducts electricity best and is used for special needs. These materials help shielding rings last long and work in tough conditions.
Standards (JIS, DIN, ASTM, BS, ISO, AISI)
Shielding rings must follow strict rules to work safely. These rules cover materials, sizes, and testing methods. The table below shows some important standards:
| Standard | Description |
|---|---|
| MIL-STD 1377 | Tests how well cables and connectors block signals from 100 kHz to 10 GHz. |
| MIL-STD 188-125-1 | Protects key ground facilities from HEMP effects. |
| ASTM D4935-18 | Checks how well flat materials block signals from 30 MHz to 1.5 GHz. |
| IEEE 299-2006 | Measures how well shielding works from 9 kHz to 18 GHz. |
These rules make sure shielding rings, like aluminum corona rings, work well in high-voltage systems.
Ring Tube Wall Thickness (2.0mm-10.0mm)
The thickness of shielding ring walls is very important. Most rings have walls between 2.0mm and 10.0mm thick. Thicker walls are stronger and resist bending better. This is crucial for systems like high voltage capacitors that face heavy stress. Picking the right thickness keeps the rings working under tough conditions.
Processing Methods (Cutting, CNC Machining, Welding, etc.)
Shielding rings are made using different methods to get their shape. These methods help the rings work well in high-voltage systems. Below are the main ways they are processed:
- Cutting: Cutting shapes the raw material into the right size. Tools like saws or lasers are used. Laser cutting is popular because it makes clean and accurate edges.
- CNC Machining: CNC machining uses computer-controlled tools to shape the ring. This method is very precise and ensures the ring fits perfectly. It’s great for making detailed designs.
- Welding: Welding connects parts of the ring when it’s too big to make from one piece. Welders make sure the joints are strong and smooth, keeping the ring sturdy.
- Bending: Bending gives the ring its round shape. Machines bend the material carefully so it doesn’t break. This step helps the ring spread the electric field evenly.
- Polishing: Polishing smooths out rough edges on the ring. A polished surface stops corona discharge by removing sharp points where the electric field could gather.
Tip: Each method helps the shielding ring work better. The choice of methods depends on the ring’s size, material, and use.
Surface Treatments (Polished Bright, Galvanized, Coating with Insulating Varnish)
Surface treatments make shielding rings stronger and last longer. They protect the rings from damage and help them handle high voltages. Here are the most common treatments:
- Polished Bright: Polishing removes flaws and makes the surface smooth. This lowers the chance of corona discharge and gives the ring a shiny look.
- Galvanized Coating: Galvanizing adds a zinc layer to stop rust and corrosion. This makes the ring good for outdoor use, like on power lines.
- Insulating Varnish Coating: Insulating varnish adds extra protection. It helps the ring resist electrical stress and weather damage. This is often used for testing equipment.
| Treatment Type | Purpose | Best For |
|---|---|---|
| Polished Bright | Stops corona discharge and sharp edges | Indoor use |
| Galvanized Coating | Protects against rust and corrosion | Outdoor systems like power lines |
| Insulating Varnish Coating | Adds electrical and weather protection | High-voltage testing equipment |
Note: Surface treatments improve how shielding rings work and make them last longer. Picking the right treatment depends on where the ring will be used.
Applications of Shielding Rings
Shielding rings are crucial in high voltage systems. They stop corona discharge and protect equipment. Below are key uses for these rings.
GIS (Gas Insulated Switchgear)
Gas Insulated Switchgear (GIS) uses corona rings for safety. GIS handles high voltage in small spaces. This raises the risk of corona discharge. The rings spread the electric field evenly. This stops harmful discharges and protects parts inside. They also help the equipment last longer. GIS systems in cities often use these rings. Their light weight and strength make them perfect for this job.
Substations and Arrestors
Substations need corona rings for reliable work. The rings lower the electric field’s strength near key parts. This stops corona discharge and saves energy. In surge arrestors, the rings block voltage spikes from lightning or switches. This keeps the arrestors working well and protects the substation. Using these rings makes substations safer and cheaper to maintain.
HV Bushings and Shunt Reactors
HV bushings and shunt reactors face strong electric fields. Corona rings protect them by spreading the field evenly. This stops corona discharge, which can harm insulation and lower efficiency. For shunt reactors, the rings keep voltage levels steady. This helps power flow smoothly. Adding these rings makes HV equipment more reliable and lasts longer.
Power Transformers and Accessories
Power transformers are key in high voltage systems. They move electrical energy between circuits for smooth power flow. But, they face problems like corona discharge. This can harm parts and lower efficiency. Corona rings fix this by spreading the electric field evenly. This stops harmful discharges and helps the equipment last longer.
Corona rings are often made of strong materials like aluminum or stainless steel. These materials are light but tough, making the rings easy to install. They also work well in harsh conditions. Adding corona rings to transformers boosts safety and cuts repair costs. This simple step keeps your system running well for years.
High Voltage Laboratories and Capacitor Banks
High voltage labs need accurate testing to keep equipment safe. Corona rings are crucial here. They control the electric field during tests, stopping corona discharge. This protects the equipment and ensures correct test results.
In capacitor banks, corona rings do a similar job. High voltage capacitors store and release energy, creating strong electric fields. Without control, these fields can waste energy and harm equipment. Corona rings spread the field evenly, lowering stress on capacitors. This improves efficiency and makes the system last longer.
HV Transmission Lines and Current/Voltage Transformers
HV transmission lines send electricity over long distances. They use very high voltages, which can cause corona discharge. Corona rings protect insulators by lowering the electric field’s strength. This stops energy loss and keeps power flowing reliably.
Current and voltage transformers also gain from corona rings. These devices measure electricity in high voltage systems. Corona rings shield them from harmful discharges. This ensures accurate readings and protects sensitive parts. Using corona rings helps keep high voltage systems efficient and dependable.
Shielding rings are very important in high-voltage systems. They stop corona discharge, which harms equipment and wastes energy. These rings spread out the electric field evenly. This lowers stress on insulators and helps them last longer. Using shielding rings keeps systems safe and working well. They are used in many areas, like power lines and testing labs. Learning how shielding rings work shows why they are useful. These rings are key for safety and good performance in high-voltage systems.
FAQ
1. What do shielding rings do?
Shielding rings stop corona discharge by spreading the electric field. They protect equipment, save energy, and help insulators last longer.
2. What materials are used for shielding rings?
Shielding rings are made of aluminum, stainless steel, or copper. Aluminum is light, stainless steel resists rust, and copper conducts electricity well.
3. How do shielding rings make systems work better?
Shielding rings protect insulators and parts by controlling the electric field. This reduces damage, cuts repair costs, and keeps systems running smoothly.
4. Where are shielding rings used the most?
Shielding rings are used in GIS, substations, transformers, and labs. They keep equipment safe and ensure systems work properly.
5. Can shielding rings be made for special uses?
Yes, shielding rings can be customized in size, material, and coating. Common coatings include polishing, galvanizing, and insulating varnish.
