More than 50% of the 
compression and pumping systems over 3 MW require 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 benefit of the state of the artwork in electric powered motors and frequency converters, the driving program for the superimposition of the planet carrier is based on a Long term Magnet Synchronous Superimposition (SI) electric motor and a dynamic Front-End Cycle Converter. So – E stands for Electric.
This is a high-speed gear drive system incorporating elements that allow the use of a low-cost constant-speed (electric) driver for a variable-speed application.
A lot more than 50% of the compression and pumping systems over 3 MW need a variable-speed drive. Frequently medium-voltage motors fed by frequency converters and parallel shaft gears are selected. Others are employing epicyclic gears with a hydrodynamic superimposition drive.
It started with hydraulic Variable Speed Gearbox liquid couplings generating slippage with results very little 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, simultaneously, the expense of the shaft trains increased, therefore did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and kept VFD out of several applications.
Taking advantage of the state of the artwork in electric powered motors and frequency converters, the driving system for the superimposition of the planet carrier is founded on a Permanent 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 components 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 electric motor. In a normal situation, the vibration will become monitored and stored on a periodic basis. If the 360 Hz signal is present in the vibration spectrum, it is not normally of any concern. If, however, additional unexplained frequencies appear in the vibration spectra, after that it would be advisable to have a look at both current waveform and the existing spectrum. In the pages that follow, some examples of problems found out in DC drives and motors are provided.”
It started with hydraulic liquid couplings producing 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 increased, therefore did efficiency. The issue of THD (Total Harmonic grid Distortion) rose and kept VFD out of several applications.