Recovery-Voltage Characteristics or Typical Transmission Systems and Relation to Protector-Tube Application

1. This paper presents a general picture of the recovery-voltage characteristics of transmission systems obtained from the study of nine selected systems subjected to the varying factors encountered in practical operation. The a-c calculating-board method has been of major importance in carrying out this investigation. 2. The recovery-voltage characteristics of systems subjected to faults which are cleared without a line-sectionalizing operation are much less severe than that for the clearing of the last circuit breaker on a bus. This difference is so marked that advantage should be taken of it, in the design of certain pieces of apparatus. 3. The method of analysis and the data presented should be of value in the application of certain pieces of apparatus and in the preparation of test codes for specific devices. 4. This general analysis is of immediate interest in connection with the application of protector tubes, and operating experience with this device supports the analysis. Erosion of the protector tubes due to operation is such that the insulation-recovery characteristics are not changed at an impractical rate.