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DC winding resistance testing of a power transformer increases the residual flux of the transformer. If it is not demagnetized following the testing, the transformer retains a high level of residual flux. Therefore, when the transformer is returned to service, the voltage required to drive the transformer into saturation is decreased. When a generator step-up transformer is returned to service following...
Paralleling current transformers (CTs) is a common practice in differential or line protection applications where the number of CTs exceeds the number of relay current inputs. This is especially true of line current differential applications applied to breaker-and-a-half and ring-bus configurations. This paper discusses complications that can arise from this practice and highlights relay design improvements...
The power system is designed to operate over long periods of time without an interruption in service. However, it is inevitable that at some point, some portion of the system will be shut down, whether for maintenance or because of a disturbance. In the second case, it is essential that the system be restored quickly and orderly. This may require one or more generators with black-start capability...
Generators are critical components of the power system. In addition to being some of the most expensive pieces of equipment on the system, they are also extremely critical to power system stability. A false trip can lead to extensive testing in search of a nonexistent fault, while a delayed trip can result in unnecessary additional damage to equipment. Both misoperations result in excessive equipment...
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