A lot more than 50% of the compression and pumping systems above 3 MW require a variable-speed drive. Frequently 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 artwork in electric motors and frequency converters, the driving system 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 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 need a variable-speed drive. Often 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 fluid couplings Variator Gearbox producing 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 problem of THD (Total Harmonic grid Distortion) rose and held VFD out of many applications.
Taking benefit of the condition of the art in electrical motors and frequency converters, the driving system for the superimposition of the earth carrier is based on a Long lasting Magnet Synchronous Superimposition (SI) electric motor and an Active Front-End Cycle Converter. So – E stands for Electric.
That 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.
All of the above plots were taken by analyzing the existing to the engine. In a normal circumstance, the vibration will become monitored and kept on a periodic basis. If the 360 Hz signal exists in the vibration spectrum, it isn't normally of any concern. If, however, various other unexplained frequencies appear in the vibration spectra, after that it would be advisable to check out both current waveform and the current spectrum. In the web pages that follow, a few examples of problems discovered in DC drives and motors are provided.”
It started with hydraulic liquid couplings producing slippage with results not much 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 cost of the shaft trains improved, and so did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and held VFD out of many applications.