Dynamatic Variable Speed Eddy Current Drives and Controls Solve an Aging Infrastructure Problem

After 36 years of service, the original controllers, at the Columbus Ohio pump station began to overheat. To compensate, the pump station installed temporary air conditioning to cool the controls to address this infrastructure problem. This kept them in service while they made plans for a permanent solution. An Engineering company was contracted to diagnose the problem. They recommend a solution, by designing extensive upgrades to the pump station, including refurbishments to the 41-year-old pumps. They decided that variable speed would still be required, thinking that VFDs would be the obvious choice. However, since it was originally eddy current drives, DSI/Dynamatic was invited to visit the site to offer suggestions for solving the controller overheating, as well to evaluate the condition of the existing motors and eddy current drives.

Dynamatic noticed that the controllers were operating at a higher level of current than the nameplate required, which accounted for the overheating. The excess current was evidence that there was a problem with the field windings in the eddy current drives. At this point, Dynamatic was asked to offer a comprehensive overhaul of the existing units, including the motors.

After interviewing Dynamatic and several VFD/Motor vendors, the City and Engineer concluded that Variable Frequency Drives, cost, space considerations and cooling requirements were not favorable for the project. Their best option was to replace the Eddy Current Drives in kind with new Dynamatic SPMV-8260 units, they are rated at 1250hp, 514 rpm, 4160 volts. The most influential factor for the replacement, was the expected life span of the products. They received one report from a VFD vendor, to expect the life span of a VFD to be about 7 years. Dynamatic drives and digital controls have been proven to outlast VFDs by as much as 6:1, dramatically reduce the pump stations lifetime operating costs.

left: ideal Electric Units CAV61320 vintage 1976 unit Right: Dynamatic SPMV-8260 unit both installations are rated 1250hp, 514rpm, 4160 volts