Transformer insulation is one of the most significant parts of an electrical system, yet very few people understand how it is used or how transformer insulation contributes to the overall operation of their electrical system. It provides proper insulation at each of the high-voltage electrical windings inside the transformer to allow the transformer to perform its intended function.
It is also used to maintain the long-term safety and reliability of the transformer and the electrical system. Therefore, if you own a business in Riverview, MI, and want to continue to be reliable and prevent costly downtime due to transformer malfunctions, it is critical that you understand the benefits associated with using quality transformer insulation solutions.
This blog provides detailed information on why insulation is important, what insulation does, what causes insulation failures, and how timely preventative maintenance can improve the lifespan of your transformer.
What is Transformer Insulation and Why Is It Important?
Transformer insulation serves as a barrier between the high-voltage energized parts of the transformer. By providing insulation between the electrical windings and components, transformer insulation prevents electrical breakdowns, reduces the heating of the transformer, and also helps maintain stable voltage levels throughout the entire electrical system.
No matter how well-built a transformer is, it will eventually fail (failure may occur from malfunction or catastrophic failure) without reliable transformer insulation.
High-voltage transformers have to be designed to perform under extreme temperatures, extreme levels of moisture, and extreme mechanical and electrical stresses; therefore, transformer insulation must be able to withstand all of these factors.
When transformer insulation is maintained and working as it was originally designed, the transformer will operate properly and safely. When the transformer insulation is not working properly, the entire transformer system is at risk.
Types of Transformer Insulation Available
Different types of transformers will require different types of insulating material based upon the voltage of the transformer, the environment in which the transformer operates, and the magnitude of the load being placed on the transformer. Each category of insulation has specific properties that allow for the best system performance, ultimate durability, and heat resistance.
- Solid Insulation
Solid materials such as pressboard, cellulose paper, and epoxy provide structural and dielectric stability to a transformer. Typically used within the distribution transformer and capable of lasting a lifetime if properly cared for, solid insulation withstands mechanical stress and allows for adequate clearance of components from one another.
- Liquid Insulation
As transformer oil circulates inside a transformer, it acts as both an electrical insulator and a coolant. During operation, when a transformer reaches its operating temperatures, it needs an effective means of removing excess heat. Quality oils used within transformer insulation are exceptional for reducing moisture ingress, which is one of the leading causes of degradation to insulation integrity.
- Composite Insulation
The newest form of transformer insulation technology continues to come from composite materials, which provide greater thermal resistance, lower moisture absorption, and higher durability than traditional materials. Composite insulation materials are specifically designed for use in high-voltage transformers, as well as in outdoor locations where temperature extremes and harsh environmental conditions will have a significant impact on the prospective life and usability of the transformer.
By understanding these types, transformer insulation companies in Riverview will be better prepared to select the proper insulation for their specific needs.
Causes of Failure of Transformer Insulation
No matter how well-built the insulation of a transformer, eventually it will fail. Understanding the common reasons for insulation failure will make it easier to take steps toward preventing costly downtime due to insulation failure.
- Heat Stress
The continuous exposure to high temperatures results in accelerated degradation of insulation. The largest contributor to transformer insulation breakdowns is overheating. With the degradation of insulation becoming rapidly greater than its increase in strength, the dielectric strength of the insulation becomes progressively less, and there is an increased likelihood of breakdown.
- Moisture Infiltration
Moisture is a very damaging element to insulation. Moisture reduces dielectric strength and can cause partial discharge, both of which create conditions that promote the premature breakdown of insulation systems. Oil-filled transformers are especially vulnerable to moisture damage due to seal and gasket failure.
- Electrical Stress
Electrical stress on an insulation system can be caused by overloading and/or excessive voltage spikes. Repeated electrical stresses on the insulation can generate micro-cracks in the insulation that ultimately lead to the total breakdown of the insulation.
- Mechanical Vibration
As long as they are operating, transformers experience mechanical vibrations. These continuous mechanical vibrations will weaken insulation due to the creation of stress points and/or cause portions of the transformer to shift, damaging the insulation.
- Age and Oxidation
The insulation materials degrade as they age and lose properties. The degradation of paper insulation causes brittleness, the oxidation of oil, and the breakdown of the composite materials; therefore, if aging materials are not continuously tested and maintained, the likelihood of sudden breakdown of the insulation system increases.
Why A Professional Maintenance Plan Is A Must
Having regular inspections and professional maintenance helps to identify small issues that can develop into very costly failures. The technician will use temperature tests, moisture tests, insulation resistance tests, and oil quality tests to assess how healthy the insulation is before evaluating transformer performance.
Reliable results can be achieved through testing methods like DGA (Dissolved Gas Analysis) and insulation resistance tests, as well as through thermal imaging, providing a comprehensive analysis of transformer conditions.
WM F McGraw is an established transformer insulation supplier, specializing in maintenance, testing, and insulation services for over 30 years. With decades of experience in the Electrical Energy Industry, WM F McGraw specializes in providing professional, precise, and long-term value through their transformer insulation services in Riverview.
Need help with your transformers? Feel free to contact us today to receive a free consultation.
Frequently Asked Questions (FAQs) About Transformer Insulation
- How often should transformer insulation be tested?
Industry standard is to perform transformer insulation testing at least once per year, but some transformers that are running at higher design loads or are utilized in mission-critical operations should perform transformer insulation testing more often. - What happens if a transformer insulator becomes damaged beyond repair?
If an entire insulator fails, the damage will generally result in internal arcing and resultant overheating and possibly transformer explosion, and require immediate replacement or repair. - Does speeding up the aging process of a transformer insulator allow a company to postpone replacing the insulator?
Yes, but when an insulator has failed due to moisture or an insulator is damaged too badly to repair, it usually requires complete or partial non-insulating material replacement. - How does moisture in transformers’ insulating material affect the insulator?
Increased moisture levels will reduce the transformer’s dielectric strength of the insulator and increase the likelihood of partial discharge, which will generally result in insulator failure. - Does temperature affect the life expectancy of insulators in transformers?
Yes, the hotter the transformer operates, the more likely it is to break down, and therefore, the better the cooling and control of electrical loads, the more likely the insulators will last.
