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Learn about power transformers — construction, working, testing, protection, and maintenance for efficient voltage transformation in power systems.
Definition of Transformer A transformer is a static electrical device that transfers electrical energy from one circuit to another without changing the frequency. Faraday’s Law of Electromagnetic Induction Let us recall our knowledge of Faraday’s Law of Electromagnetic Induction. Because it is essential for the working principle of a transformer. This famous law states that … Read more
A transformer is a static electrical device that transfers electrical energy from one circuit to another through electromagnetic induction, without any physical connection. Since, a transformer works bases on electromagnetic induction, it only works on an AC supply and can step up or step down voltage levels without changing its frequency. The transformer consists of … Read more
Before entering the article on the transformer vector diagram or the transformer phasor diagram, we may recall our concept of an ideal transformer. For a basic idea of an ideal transformer, you may also read our article on the emf equation of a transformer. Considering Core Losses for Transformer Vector Diagram Now, we shall consider … Read more
The vector diagram shows the phase relationships clearly. It reveals how currents and voltages interact physically. Moreover, it guides us in circuit element placement. Each vector represents one specific circuit component. Therefore, the diagram becomes our blueprint for the equivalent circuit of a transformer. Without it, we cannot understand parameter connections properly. Vector Diagram No … Read more
Cause of Voltage Regulation Every electrical source has some internal or inherent impedance. It may be a battery, a transmission line, a power transformer, or any other device that can supply electric power. Due to this inherent impedance, there is always a voltage drop in that system. When we measure the voltage across the open … Read more
Two types of losses occur in a transformer. We refer to these losses collectively as losses in Transformers. These two losses are no-load losses and copper losses. We also often refer to the no-load losses as core losses. These losses occur due to the magnetic material of the core of the transformer. These losses include … Read more
Not only a power transformer, but all transformers have only two main parts. These are the windings and the core. All other parts associated with the transformer are just there to support the working of the transformer. Actually, the principle of a transformer is based on these two elements — the winding and the transformer … Read more
Traditionally, cold-rolled grain-oriented (CRGO) silicon steel has been widely used for the cores of distribution transformers and station service transformers due to its excellent magnetic properties and relatively low core losses. However, in recent years, a modern trend has emerged in the choice of core materials, especially for distribution transformers and, to some extent, station … Read more
In this article, we are going to discuss the theory behind a condenser bushing. We have mainly focused on how the capacitor grading improves the voltage distribution along the thickness of the insulation. We also call it a capacitor graded bushing. There are mainly two types of condenser bushings. These are the OIP bushing and … Read more
We also refer to a resin-bonded paper bushing or a synthetic resin-bonded paper bushing, respectively, as SRBP or RBP bushings, in short form. Before entering the actual discussion of resin-bonded paper bushings, let us understand the meaning of resin-bonded paper. What is the meaning of resin-bonded? We all know that paper is a cellulose material, … Read more
An OIP bushing uses concentric cylindrical capacitors in series between the central conductor and outer insulator housing of the bushing. An OIP bushing serves the same purpose as the other types of bushings do. That means it provides proper insulation between the live conductor and the grounded metallic tank of electrical equipment, such as power … Read more
Type Tests for the transformer Routine Tests on the Transformer Stage Inspection Tests On Core: On Coil On Tank Acceptance Tests
RIP bushing is a kind of condenser bushing or capacitor-graded bushing. The full form of RIP bushing is Resin Impregnated Paper Bushing. The working principle of an RIP bushing is similar to that of an OIP bushing, and construction-wise, they are almost similar. The only difference is that in an OIP bushing, we use oil … Read more
What is a Transformer Breather? A transformer breather (silica gel breather) is a simple device that keeps moisture out of the transformer. We fit it to the pipe coming out from the transformer conservator tank. When the transformer heats up, the oil expands. When it cools down, the oil contracts. This creates a breathing action. … Read more
The Buchholz Relay is a gas-actuated protection relay. It is a mechanical relay. All oil-immersed transformers that have a conservator tank should be equipped with a Buchholz relay. A Buchholz relay can detect both slow-developing faults and major transient faults occurring within the transformer. It provides an early warning (alarm) for slow-developing faults and initiates … Read more
Type Tests on New Transformer Oil or Insulating Oil
An Oil Surge Relay, or OSR, is a type of mechanical relay. It operates in response to a sudden oil surge. Need for Separate Diverter Tank Every modern power transformer includes an On-Load Tap Changer (OLTC). During tap-changing operations, some arcing always occurs at the diverter switch contacts. It is desirable to change tap positions … Read more
The Nitrogen Injection Fire Protection System (NIFPS) prevents and extinguishes fires in oil-filled transformers. Thereby, it safeguards critical power infrastructure. We also commonly call it the Nitrogen Injection Fire Prevention & Extinguishing System (NIFPES). This system operates on a “drain and stir” principle, effectively mitigating fire hazards through a coordinated sequence of actions. Working Principle … Read more
A power transformer has high cost, large size, and complex design. So, identifying defects at the final stage of manufacturing can lead to significant delays, expenses, and operational challenges. Therefore, standards always recommend performing different tests and inspections during various stages of manufacturing. That means the standards always prefer to perform stage inspections of a … Read more
The clearance requirements for HV and LV terminals in the air are as follows:For 66 kV side, the phase-to-phase and phase-to-earth clearance should be 700 mm, and 660 mm respectively.For 12 kV side, the phase-to-phase and phase-to-earth clearance should be 280 mm, and 140 mm respectively. The following points should be noted for designing winding … Read more