Soft starter devices for powerful turbomachines and other mechanisms with free starting

To eliminate or reduce the negative consequences of direct starting of a motor, soft starter devices (SSDs) are used. Recently, SSDs that are constructed using a thyristor voltage regulator scheme have gained increasing popularity. However, their use is not always justified because of high cost, complexity, and the need to use additional equipment for operation at low temperatures. This paper shows a possible way to solve these problems using simple and reliable soft starter devices on passive elements of RUPP type. Results of the development and creation of a series of such devices are reviewed. A simpler design, durability, and ability to work practically in all operating conditions, as well as lower cost and absence of need for maintenance during operation, are distinctive features of RUPP compared with semiconductor analogues.