More than 50% of the compression and pumping Variable Speed Gearbox systems above 3 MW need a variable-speed drive. Often medium-voltage motors fed by frequency converters and parallel shaft gears are chosen. Others are using epicyclic gears with a hydrodynamic superimposition drive.
Taking advantage of the condition of the art in electric powered motors and frequency converters, the driving program for the superimposition of the earth carrier is founded on a Long lasting Magnet Synchronous Superimposition (SI) engine and a dynamic Front-End Cycle Converter. Therefore – E stands for Electric.
That is a high-speed gear drive system incorporating elements that allow the usage of a low-cost constant-speed (electric) driver for a variable-speed application.
More than 50% of the compression and pumping systems above 3 MW require a variable-speed drive. Often medium-voltage motors fed by frequency converters and 
parallel shaft gears are selected. Others are using epicyclic gears with a hydrodynamic superimposition drive.
It started with hydraulic fluid couplings creating slippage with results not much better than the throttle.
The look of hydraulic clutches then improved and included a torque converter and a superimposed epicyclic drive.
Adjustable Frequency Drives (VFD) were developed and, at the same time, the expense of the shaft trains improved, and so did efficiency. The issue of THD (Total Harmonic grid Distortion) rose and kept VFD out of several applications.
Taking benefit of the state of the artwork in electric motors and frequency converters, the driving program for the superimposition of the earth carrier is based on a Long term Magnet Synchronous Superimposition (SI) engine and an Active Front-End Cycle Converter. Therefore – E stands for Electric.
This is a high-speed gear drive system incorporating parts that allow the use of a low-cost constant-speed (electric) driver for a variable-speed application.
All of the over plots were taken by analyzing the current to the motor. In a normal situation, the vibration will end up being monitored and kept on a periodic basis. If the 360 Hz signal is present in the vibration spectrum, it is not normally of any concern. If, however, various other unexplained frequencies appear in the vibration spectra, then it might be advisable to check out both current waveform and the existing spectrum. In the web pages that follow, a few examples of problems uncovered in DC drives and motors are shown.”
It started with hydraulic liquid couplings making slippage with results not much much better than the throttle.
The look of hydraulic clutches then improved and included a torque converter and a superimposed epicyclic drive.
Variable Frequency Drives (VFD) were developed and, simultaneously, the expense of the shaft trains improved, and so did efficiency. The issue of THD (Total Harmonic grid Distortion) rose and kept VFD out of many applications.