It's good to go backwards — Sometimes

摘要

Large, solid pole synchronous motors are in common use today across many industries and applications. International testing standards are well known by manufacturers and users alike. However, no current standard specifies testing methods to simulate the heat generated during asynchronous starting. The energy absorbed and the heat generated is significant and may produce surface temperatures that exceed 400 °C. This heat produces differential expansion between different materials as well as within the depth of the pole itself. The full impact of this effect is not known until the motor meets the driven equipment (and electrical system) at site, i.e., the first coupled start. A test method has been developed that ensures motors can be tested in the factory with the same energy being absorbed as at site. This gives the user (and motor manufacturer) far greater confidence in the design and avoids any unexpected `surprises' that may occur during the first or subsequent starts at site.