Patent ID: 9697962
Date: 2017-07-04
CPC Classifications: H01H,H02J

Claim:
1. An on-load tap changer for making tap changes in a transformer winding, the tap changer comprising (a.) a tap change module connected to the transformer winding and comprising a bypass switch assembly, a vacuum interrupter assembly and a selector switch assembly; (b.) a motor connected to rotate at least one shaft, wherein the at least one shaft is connected to the tap change module and is operable upon rotation to cause the tap change module to perform a sequence of operations that effectuate a tap change, the operations comprising actuating the bypass switch assembly, actuating the vacuum interrupter assembly and actuating the selector switch assembly; (c.) a multi-turn absolute encoder connected to the at least one shaft and operable to determine a position of the at least one shaft; and (d.) a monitoring system connected to the encoder to receive the position of the at least one shaft and operable to monitor a tap change by determining from the position of the at least one shaft where the tap change module is in the sequence of operations, wherein the monitoring system is operable to monitor the tap change by measuring the time required to perform at least one of the operations and determining that an error has occurred if the at least one of the operations was not timely performed, wherein the monitoring system is further operable to measure the total time required to perform all of the operations, and wherein an error is determined to have occurred if the total time required to perform all of the operations is greater than a predetermined amount of time, and wherein none of the operations are individually timed.