STS 400
STS 400
STS 400
STS 400

Product Summary

The Speed Trimming Sheave (STS) is a patented, fail-safe design which enables precise modulation of cooling fan speeds in the compression application. The STS reduces power and labour costs while increases productivity with minimal maintenance.
In a typical application, STS can run a cooling fan between 110% and 60% of its nominal speed, either for providing more cooling power on hot summer days (no more cooling-capacity related shut-downs), or for slowing down the fan when exposed to colder ambient conditions (no more over-cooling, no re-pitching the fan-blades, no more noise). Somewhat counter-intuitive, despite its weight STS actually lowers side-load on the crank-shaft due to lower belt-pull when fan-speed is lowered which is better than 90% of the time.
The question now is: “What is the STS pay-back time?”  The answer depends on user sensitivities:

  • If the primary concern is fuel savings (power needed to drive the fan), it will typically take 2 – 3 years before the STS costs are recovered;
  • If the primary concern is maintenance and downtime (seasonal re-pitching and related), we are still talking 1 – 2 years;
  • If the primary concern is increased production (no summer shut-downs), the answer is: ONE DAY;
  • If you worry about environment and noise pollution, stop worrying; whenever fan-speed is trimmed (even as little as 5%), fan-related noise is dramatically reduced. When coming close to an STS-equipped package at night, the only noise you can hear is from exhaust.

STS 400 Product Specifications

Weight – 220 LB (100 kg)
Overall Dimensions – 11.6” Wide X 12.4” High X 16.5” Long (295 mm X 315 mm X 419 mm)
STS Sheave Datum Diameter – 11.2 Inches (284.5 mm)
STS Sheave Type – C-type, 6 grooves
Rated Input Torque – 295 ft-lb (400 Nm)
Maximum Engine Speed – 1,200 RPM

Other potential applications for MiVa Speed-Trimming Technology

  • Pipelines
  • Dredge Pumping
  • Solid Transport

Independent analyses have confirmed our assertion that pipelines may achieve 4 – 6% energy savings (as well as small capital-cost savings) by moving away from direct VFD control of medium-voltage motors. Our STS can and should be considered a proof-of-concept of a drive architecture where the main motor is connected across-the-lines, while a small, speed-trimming motor is VFD controlled to provide the necessary speed adjustment. Size of the speed-trimming motor is directly proportional to the speed variance required for the application.