An electric transformer is a static electrical machine which transforms electrical power from one circuit to another circuit, without changing the frequency. It can either increase or decrease the voltage with corresponding decrease or increase in current. Let’s learn more about what is an electrical transformer, its types and what causes it to fail.
Design of a Transformer
There are three types of electrical transformers based on the design:
- Core Electrical Transformer
- Shell Electrical Transformer
- Auto Electrical Transformer
The difference lies in how the windings are wound around each core. In auto transformers, the windings are electrically connected while it’s not the case in the other two.
What Causes Transformer Failure
You need to track the cause of the transformer failure before you can come up with a solution. There are a number of factors and a combination of these factors can result in a failure. The causes can be classified into 5 categories:
1. Imperfection of the specifications
- If you choose the wrong type of insulation
- Capacity is not right
- The condition in the place of installation isn’t right, such as presence of dampness, wrong temperature, dangerous gases, etc
2. Imperfection on the facilities
- Wrong installation
- Protection for switch and relay is wrong
- Wrong capacity and protection range of lightning rods
3. Imperfections on the operation and maintenance of the equipment
- If the insulation oil is deteriorating
- Abnormal voltage in the facility
- Excessive load in the cable connections
- Poor maintenance of the accessories
- When conducting parts get loose and heat up
- Carelessness in the arrangement of the protection circuits
- Insufficient inspection of the gaskets, electrical wire and valves
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4. Normal wear and tear
5. Natural disasters
Types of Transformer Failure
They can be classified as:
- Internal Failures: These are found in the coil and the core. Common failures include dielectric interruption, a grounding mistake, rupture and twisting of the winding, open connection of the tap charger, etc.
- Short circuits: These occur between the turns, phases and windings. Most of these short circuit failures are caused due to abnormal tensions on the surge arresters. It might also occur due to deterioration of the insulation oil and penetration of rain, deterioration due to heat that is caused by an electromagnetic mechanical force or by an abnormal excessive load.
- Short circuit to the ground: If there is an impulse voltage or a deterioration of the insulation, it will lead to short circuit to the grounding of the winding, to the tank or of the terminal to the core.
- Terminals of the winding breaking: The terminals may suffer damages if there is an excess current or a lightning strike. They can also get damaged if the short circuit accidents start accumulating and this repetitive mechanical destructive force may finally break the terminals.
- External Failures: These occur in the tank and the reasons include oil leaks in the gasket, weld cord or valve, bushings of breathers, thermometers, over pressure valve and due to defects on the forced cooling fans.
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Reason Behind Transformer Explosion
If there is a transformer short-circuit, then the electrical arc will vaporize the oil and create a dynamic pressure peak that travels at a speed of 1,200 meters per second (4,000 feet per second). This will occur every few milliseconds and the pressure peak will generate pressure waves due to the reflections in the tank. A static pressure is created as a result of an integration of all the waves pressure peaks. This pressure will equalize throughout the entire transformer tank within 50 to 100 milliseconds after the electrical arc, eventually causing the transformer tank to rupture and explode.
The electrical service to businesses or residences will be interrupted when a transformer blows. You have to replace the destroyed hardware, however, shut down the incoming electrical line to prevent injury and further damage. Based on how much damage is caused, you might have to shut off other electrical services in the immediate area temporarily to prevent stress on the electrical grid while replacing the destroyed transformer.
It is critical to understand how an electrical transformer works in order to prevent any kind of failure or to repair it after a failure.
Article written by Jeson Pitt for Prepper’s Will.
About the Author: Jeson Pitt loves to marry his marketing and blogging skills. Working for the bulk buyers of Electrical Materials, Jeson loves to channelize his thoughts into words, which has helped him establish his image as a blogger. He’s got the industry insights that you can count on.
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