Testing of Transformer A transformer is one of the most expensive and important equipment in the power system. If it is not suitably designed its failure may cause a lengthy and costly outage. Therefore, it is very important to be cautious while designing its insulation, so that it can withstand transient over voltage both due […]
Equivalent Circuit of Real Transformer We turn now to the real transformer, with the aim of developing its equivalent circuit. Real transformers behave much like ideal ones (except in very small sizes), and the approach is therefore to extend the model of the real transformer to allow for the imperfections of the real one. For
Ideal Transformer Because we are dealing with balanced 3-phase motors we can achieve considerable simplification by developing single-phase models, it being understood that any calculations using the equivalent circuit (e.g. torque or power) will yield ‘per phase’ values which will be multiplied by three to give the total torque or power. A quasi-circuit model of
Removal of moisture and impurities from insulation is one of the most important manufacturing processes. Removing moisture from the oil is relatively simple, which can be done by conventional methods of filtration or heat/vacuum cycles. However, most of the moisture is in the solid insulation (it can be as high as 99%). Hence, a challenge
A partial discharge (PD) is a transient breakdown of a part of the insulation system in high voltage equipment. By this process, the entire dielectric is not breached; that is, the breakdown does not occur between two conductors. Only a small portion of the insulation suffers a miniature breakdown. Partial discharges can be thought of
Due to severe competition and restructuring taking place in the power industry, there is a need to reduce maintenance costs, operate transformers as much as possible, extend their life, and prevent unplanned outages. Hence, in the recent years the monitoring and diagnostics of transformers have attracted considerable attention of researchers and practicing engineers. The monitoring
A transformer supplying an arc furnace has to deliver unusually high currents over a wide range of voltage. Power ratings between 50 and 100 MVA are quite common now with the secondary currents of more than 50 kA. Furnace transformers have special features for handling very high currents compared to conventional transformers. Since the LV
Duties of rectifier transformers serving special industrial loads are more stringent than conventional transformers. Electrical energy in the form of direct current is required in electrolytic processes used in aluminum smelters and chemical plants (producing chlorine, soda, etc.). Various methods used for converting AC into DC in earlier days included use of motor-generator sets, rotary
Hysteresis and eddy current losses together constitute the no-load loss according to the classical theory. The loss due to the no-load current flowing in the primary winding is negligible. Also, at the rated flux density condition on no-load, since most of the flux is confined to the core, negligible losses are produced in the structural
Hysteresis, Eddy, & Anomalous Losses of Transformer Read More »
For supplying a load in excess of the rating of an existing transformer, another transformer is usually connected in parallel with it since replacing it with a single larger unit is a costly alternative. The cost of a spare smaller rating transformer is also lower. Also, it is preferable to have a parallel transformer in