
272 Electric Motors and Drives
is able to remain synchronized with the travelling field set up
by the three-phase winding on the stator in much the same
way as a permanent-magnet rotor. Early reluctance motors
were invariably one or two frame sizes bigger than an induc-
tion motor for a given power and speed, and had low power-
factor and poor pull-in performance. As a result they fell
from favour except for some special applications such as
textile machinery, where cheap constant speed motors were
required. Understanding of reluctance motors is now much
more advanced, and they can compete on almost equal terms
with the induction motor as regard ...