More than 50% of the compression and pumping systems above 3 MW require a variable-speed drive. Frequently medium-voltage motors fed by Variable Speed Gearbox 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 artwork in electric powered motors and frequency converters, the driving 
system for the superimposition of the earth carrier is based on a Long lasting Magnet Synchronous Superimposition (SI) motor and a dynamic 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.
A lot more than 50% of the compression and pumping systems above 3 MW need a variable-speed drive. Frequently medium-voltage motors fed by frequency converters and parallel shaft gears are chosen. Others are employing epicyclic gears with a hydrodynamic superimposition drive.
It started with hydraulic fluid 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 increased, therefore did efficiency. The issue of THD (Total Harmonic grid Distortion) rose and kept VFD out of many applications.
Taking benefit of the state of the artwork in electric motors and frequency converters, the driving program 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.
That 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 above plots were taken by analyzing the current to the engine. In a normal scenario, the vibration will be monitored and kept on a periodic basis. If the 360 Hz signal exists 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 have a look at both current waveform and the current spectrum. In the webpages that follow, some examples of problems uncovered in DC drives and motors are presented.”
It started with hydraulic liquid couplings making slippage with results not much better than the throttle.
The design 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 improved, therefore did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and kept VFD out of many applications.