Abstract :
Further investigations of the problem of synchronously starting a motor from a generator have been published recently with particular reference to the case of the generator being small relative to the motor. The authors´ conclusion that this may be employed successfully when the generator rating is approximately only 15% of the motor rating is encouraging. They may be interested in the discussor´s (Mr. Ridley´s) experience in connection with machines of comparable size, but connected through two terminal transformers and a transmission line of 30 km this being appreciably longer than that referred to by Oliver and Hamlin. In replying, the original authors note that they are pleased to receive Mr. Ridley´s discussion, as it is always very useful, as well as reassuring, to see the results of act ual experience. They remark first that a line length of 30 km is not very long, and the two transformers constitute most of the impedance intervening between the two generators of his case. Second, they assure Mr. Ridley th at 15% relative generator size was not at all intended as a lower limit. As pointed out in the original paper, the total armature circuit resistance is the significant factor, rather than the generator size per se, and they have described an approximate method for predicting whether or not any particular case will be successful. This method, incidentally, gives as one of its intermediate results the limit of generator speed, about which Mr. Ridley inquires in his last paragraph.
