system are of order 12k 1. Cancellation of harmonics 6(2n1) 1 has
resulted from this transformer and converter configuration.
This principle can be expanded to arrangements of higher pulse numbers by
incorporating increased numbers of 6-pulse converters with transformers that
have the appropriate phase shifts. The characteristic ac harmonics of a p-pulse
converter will be pk 1, k 1, 2, 3, . . . . Power system converters have a practical
limitation of 12 pulses because of the large expense of producing high-voltage
transformers with the appropriate phase shifts. However, lower-voltage industrial
systems commonly have converters with up to 48 pulses.