Partial discharge, abbreviated as PD, is an important term in electrical engineering. PD is a localised dielectric failure of a small portion of a dielectric insulation system under high-voltage stress. It is a kind of spark or arc caused by factors like moisture, insulation faults, high voltage, or even mechanical damage to the insulating material.

This dielectric breakdown can impair the functionality, reliability, and effectiveness of the electrical system.

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Understanding Partial Discharge

Identifying the factors causing partial discharge is important to comprehend the core of PD. Insulation breakdown, excessive voltage stress, defects, holes, or cavities within the dielectric materials are just a few factors that precipitate PD.

Insulation breakdown, which happens when the material separating conductive areas wears off, is one of the main reasons for an electrical discharge.

Voltage stress causes the dielectric to be pushed beyond its tolerance, which can lead to partial discharge when the insulation’s capacity is surpassed. Voids or defects in the insulation could also be the source of partial discharges.

Effects of Partial Discharge

Partial discharge occurs over time, and it can jeopardize the effectiveness of the insulation. This can increase the risk of equipment failure due to voltage fluctuations, which would pose a menace to the safety and reliability of electrical systems. TEV (transient earth voltage) testing, ultrasonic testing, and corona detection are the ways to detect partial discharge.

How does Partial Discharge Occur?

From manufacturing to operation, PD can ensue at different stages of an electrical system’s lifespan, including defects during the manufacturing, assembly, or installation of the equipment, physical damage from external factors, operational damage, etc.

Let’s look at some examples of how partial discharge occurs:

• During manufacture: Solid insulators are designed to supply electrical stress evenly, but manufacturing defects can cause small cavities, holes, or voids.
• Equipment installation: Errors or common mistakes that occur while assembling the item or its installation can fail, weaken or damage insulation, or increase electric stress across it.
• Aging and deterioration: It’s common that aging or deterioration can weaken the insulation, making it less resistant to electrical stress.
• Overstressed in service: Short circuits, static bursts, or lightning strikes can cause overloads to the insulation that could result in permanent damage.
• In-service damage: External factors like heavy vehicles or work on the road can also result in PD, which can be difficult or even devastating for electrical equipment.

Applications and Industries Affected by Partial Discharge (PD)

Partial discharge is a major concern across industries. It can impede operations or hinder operational safety in areas including motors and switchgear, transformers and generators, the aerospace industry, and the automotive industry. This can cause fires, outages, or other minor and major concerns.

Partial discharge, which poses a number of safety concerns and may result in damage, can happen to electrical equipment. It can happen in rotating machinery like motors and generators as well as high-voltage equipment like power lines, transformers, and switchgear.

Even the aerospace and automotive industries are susceptible to PD because of high-voltage components like radar systems and avionics in the aerospace industry and electric motors and hybrid vehicles in the automotive industry.

Early detection and prompt intervention are essential for the reduction of PD symptoms. Techniques for identifying PD include corona detection, TEV testing, and ultrasonic testing. Monitoring PD regularly can help in identifying a problem on time, and taking prompt action, including repairing, restoring, or replacing the insulation, can prevent damage. This is solely done depending on the application or tools.

The PD Detector Pro, powered by Technomax, is one of these methods that can be of great help. It’s important to note that insulation deterioration can result in damages, including short circuits that can cause safety hazards, power outages, and even financial losses. By implementing PD mitigation measures, you can ensure the safety and reliability of electrical equipment.

Why Does PD Occur at Normal Working Voltages?

There are different types of partial discharge, each with different characteristics and effects. The types include arching discharge, corona discharge, void discharge, surface discharge, etc. Partial discharge happens when insulation breaks down under high tension and fails to cope with the electrical stress.

Surface Tracking

Surface tracking hits the surface of an insulator. It happens when dirt or moisture builds up on the surface, degrading the insulation.

With enough voltage, a conducting channel develops on the insulator’s surface, which could eventually result in an arc flash or fire due to the insulation’s increasing ablation. Always keep insulators dry and clean and check for any signs of wear and tear to prevent surface tracking. If signs of deterioration are found, they must be fixed right away.

Types of Partial Discharge

• Corona discharge: The corona discharge is a type of partial discharge that occurs when electricity arcs from a sharp conductor to the surrounding air. It is generally not harmful but can cause noise and radio interference.
• Arcing discharge: Arcing discharge is a type of destructive electrical discharge that can cause damage to insulation. This happens due to the flow of electrons occurring in a gaseous or vacuum environment.
• Surface discharge: As the name implies, here the partial discharge travels along the surface and is due to moisture or debris on the surface. This is among the most destructive types of PD and causes severe damage.
• Void discharge: The void discharge is highly destructive and can result in complete failure of the insulation. This occurs due to a void or defect in the bushings, insulation of cables, GIS junction insulation, etc.

Detection and Measurement Techniques

To avoid catastrophic failures, it’s important to identify partial discharges. In high-voltage equipment, partial discharge is a sign that the insulation is ready to fail, which could lead to grid overload, insulator deterioration, fires, and downtime.

Any inadequacy in identifying PD calls for intensive training as it is unable to see partial discharge through closures or is too imprecise to demand an immediate repair. Moreover, one or many such inadequacies can force the user to stand near potentially deadly tools or equipment. 

To offer a more precise way to detect PD, Technomax, which provides high-quality solutions for industrial sectors including the distribution of electrical, mechanical, and condition monitoring equipment, has introduced PD Detector Pro, a handheld device with a 3.5-inch touchscreen display that makes analysing obvious and simple to comprehend.

PD Detector Pro’s outstanding design and cutting-edge features make it the most efficient and user-friendly PD detector for high-voltage assets. It can also discriminate between PD and noise levels and automatically synchronise with the 50/60 Hz system frequency. 

Early detection of PD is essential to preventing disastrous failures. Several detection methods, including electrical (ultrasonic, TEV, and UHF) and non-electrical (acoustic, optical), are used to identify and measure PD activity. Sensors and monitoring systems are necessary for these detection methods.

Advancements in Partial Discharge Testing

Groundbreaking advancements in PD testing have introduced several online and offline methods for partial discharge testing in recent years. They include -sensitive and accurate PD sensors, data analytics, and digital signal processing powered by artificial intelligence that offer more reliable and precise information.

Unlike conventional PD sensors, newer PD sensors are technologically advanced and can detect even a small amount of PD. This can be used even by laypeople. All this made it possible to detect and diagnose insulation problems earlier and thereby improve the safety and reliability of electrical equipment.

Mitigation and Prevention Strategies

Partial discharge accelerates the aging of electrical equipment, failures in insulation, and even fire. Here are some strategies that can be employed to mitigate and prevent partial discharge:

• Designing for high-voltage insulation: Thicker, high-voltage insulation materials can help the equipment withstand the high electric fields that can lead to partial discharge.
• Minimising defects in the insulation: Being watchful during the manufacturing process and using high-quality materials can help minimise insulation defects.
• Reducing contaminants: Contaminants are the main cause of PD, and they can be reduced by using clean materials and handling them properly.

By considering the above-mentioned strategies, it is possible to mitigate the adverse effects of partial discharge and extend the lifetime of electrical equipment.

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Future Trends in Partial Discharge Management

Several new technologies that ameliorate predictive maintenance using artificial intelligence, IoT, and remote monitoring have come to the forefront of PD management. Advanced research on developing new PD detection sensors, analysis algorithms, high-quality insulation materials, etc. is opening newer opportunities for PD management in the future.

Ultrasonic sensors (used to detect PD through sound waves), optical sensors (detecting PD through light emitted), and artificial intelligence are just a few examples of future trends being developed for partial discharge management.

IPEC: Pioneers in Partial Discharge Monitoring

At IPEC, they're dedicated to revolutionizing the field of electrical asset management through cutting-edge Partial Discharge (PD) Monitoring devices. With decades of experience and a passion for innovation, they have emerged as industry leaders in providing reliable, high-precision solutions for detecting and managing partial discharge activity in electrical systems.

Their mission is to ensure the safety, reliability, and longevity of electrical assets worldwide. They strive to empower their clients with state-of-the-art PD Monitoring devices that deliver accurate, timely information to prevent costly downtime, avoid catastrophic failures, and ultimately, save lives.

Their PD monitoring solutions have been deployed across a diverse range of industries, including:

1. Power Generation
2. Transmission and Distribution
3. Oil and Gas
4. Manufacturing
5. Healthcare
6. Transportation

Ready to take the next step in safeguarding your electrical assets? 

Being the authorised distributor of IPEC monitoring devices in the Middle East, we can offer tailored solutions that can be customized to meet the specific requirements of your application.

Our team of experts will work closely with you to design a monitoring solution that fits seamlessly into your existing infrastructure.

Final Wrap

While partial discharge is a complex aspect of electrical engineering, understanding its impact, early detection, and development and execution of prevention strategies are prerequisites to ensuring the safety, dependability, and reliability of these systems.

Collaboration and knowledge sharing within the electrical industry are important as we try to demystify partial discharge and protect our electrical infrastructure.