Cost-effective motor surge capability

The use of surge capacitors to protect medium voltage induction motor windings from steep-fronted power surges has long been an accepted industry practice. Claims have been made that motor reliability would be improved without the use of surge capacitors if added interturn insulation were incorporated within the motor winding. This paper explores the surge-withstand ability of motors and the surge standards that have emerged. It presents a survey of industry practices and studies related to current motor applications, and provides the motor user with an economic evaluation to arrive at a cost-effective selection of motors with or without external surge protection     

Selection and Application of Multispeed Motors

Multispeed induction motors can be used as pump or fan drives in certain petroleum and chemical industry applications to accommodate variable operating conditions. Use of multispeed motors in these cases can reduce equipment or energy costs. Applications for multispeed motors may not be considered during the project design stage because of the relatively limited use of these motors in the industry. The available types of multispeed motors and the potential cost savings associated with their use are reviewed.