Energy - has long been an integral partcivilization. It is simply impossible to imagine life without it. That is why the issue of the continuity of energy supply to consumers is becoming increasingly acute. The parallel operation of transformers is one such way. However, is this method used only for reservation, and what are the requirements for the equipment?
As already mentioned above, the initially agreedthe work was caused by the need to improve the reliability of electricity supply. However, there are other, no less important features, when parallel operation of transformers is necessary. Such moments include:
Switching transformers on parallel operationprovides redundancy of especially responsible receivers of electrical energy, which implies the uninterrupted power supply. Most substations use two or more transformers (exceptions are low-power substation type). Work in parallel is allowed if both transformers meet a certain set of requirements, which are called "Transformer Parallel Operation Conditions":
If one of the two transformers is damagedit is always possible to pick up absolutely the same one, which completely corresponded to the damaged by the conditions and operating modes. In these cases, the choice of the transformer is based on complex preliminary calculations, which show that the windings of both transformers will be loaded evenly, and none of them will not be overloaded by the load capacity of each individual transformer.
Parallel operation of transformers is possible withthe relative equality of the values of the short-circuit voltage on the windings. If the values of the faults are different, then before switching on in the joint operation, it is necessary to first change the transformer ratio of one transformer using a special switch. In this way, it is possible to achieve compensation of the redistributed loads that arise due to differences in short-circuit voltages. Due to this discrepancy, the equalizing currents will not overload the transformer with a lower short-circuit voltage.
Naturally, it is necessary to take into account loadingability - both separately from each electrical appliance, and during such an event as the parallel operation of power transformers. At idle, however, the difference in the values of the short-circuit voltage is not affected at all, because the transformation coefficients are equalized and become the same. Under the load, the secondary voltages will be different, since unequal voltage drops can lead to the flow of equalizing currents along the windings, while in one transformer the equalizing current will be added to the main current, and the second will be subtracted. The recommended ratio of the powers of the most powerful transformer to the lowest power should be no more than three to one.
Possible parallel operation of transformersthree-winding, two-winding on all windings. It must be remembered that for electrical appliances connected in parallel, the load is distributed in inverse proportion to the short-circuit voltage and is directly proportional to the power of each individual transformer. The parallel operation of the transformers, if the winding connection groups are different, is possible on all odd groups. If the switching is not coordinated, a voltage arises between the clamps of the secondary windings due to the angle of shear, which causes an unacceptable equalization current.