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Grounding transformers are used to obtain a neutral when an existing delta-connected or ungrounded systems are to be grounded. These transformers provide a path for the flow of fault currents during unbalanced ground faults. They can be found in transformer substations where neutral might not be available as the transformer windings are delta connected. Types … Read more
A Rogowski coil is an electrical transducer, that functions similar to a current transformer and is used in a variety of applications to measure alternating current (AC). It is named in honor of German physicist Walter Rogowski for his contributions to the field of electronics. Construction-wise they are a bit different from the normal current … Read more
Transformers are the most efficient electric machine. A typical transformer is over 99% efficient. The small inefficiency is due to copper losses, core losses-hysteresis and eddy currents losses, stray and eddy current losses occurring in the transformer. These losses result in temperature rise. Various transformer cooling methods are adopted in order to maintain sufficient operating … Read more
Transformer windings constitute the electrical circuit of a transformer. They are made up of current-carrying conductors wound around the core. The primary windings form the input to the transformer and the secondary windings form the output. The construction of the transformer windings should be stable enough to ensure safe operation. It should also be mechanically … Read more
Insulation materials are one of the most important elements in a transformer. They are used to electrically separate the conducting parts of a transformer from each other and from other components. Internal insulation failures are the major cause of transformer failures. This article intends to give you an overview of insulation materials used in transformers. … Read more
A transformer core serves the following three important purposes: Provides mechanical support to the windings. Provides a low reluctance closed ferromagnetic path to the magnetic flux. Reduces the losses due to flux leakage. The primary and secondary windings of a transformer are wound over the core but physically separated from each other. The transformer core … Read more
In electric machines, a varying magnetic field causes eddy currents in all metallic parts and hysteresis in ferromagnetic core. The losses caused due to eddy currents are known as eddy current loss and that caused due to hysteresis is known as hysteresis loss. In the following sections, we will learn, eddy currents, the phenomenon of … Read more
In order to supply loads exceeding the rating of an existing transformer, two or more transformers are connected in parallel to the existing one. The parallel operation of transformers facilitates load sharing between the transformers. When a connected load at a load centre exceeds the MVA of the existing transformer, it is easier and economical … Read more
What is an instrument transformer? Instrument transformers are current and voltage transformation devices that are used to step down the transmission and distribution line voltages and currents to levels that can safely operate measuring instruments, protection devices and control relays by isolating it from the supply voltages. The above diagram shows the basic usage of … Read more
Current transformers (CT) and Potential Transformers (PT) are instrument transformer types used to step down transmission or distribution line voltages and current to the level that can be measured using measurement devices or controlled using control devices. The principle of operation of a certain type of CT and PT are similar to power transformers. Here … Read more
