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 chosen. Others are employing epicyclic gears with a hydrodynamic superimposition drive.
Taking benefit of the state of the art in electrical motors and frequency converters, the driving program for the superimposition of the earth carrier is founded on a Permanent Magnet Synchronous Superimposition (SI) engine and a dynamic Front-End Cycle Converter. Therefore – E means Electric.
That is a high-speed gear drive system incorporating parts that allow the use of a low-cost constant-speed (electric) Variator Gearbox driver for a variable-speed application.
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.
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.
Variable Frequency Drives (VFD) were developed and, simultaneously, the price of the shaft trains improved, therefore did efficiency. The issue of THD (Total Harmonic grid Distortion) rose and kept VFD out of several applications.
Taking benefit of the condition of the art in electric powered motors and frequency converters, the driving system 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 utilization 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 engine. In a normal circumstance, the vibration will end up being 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, other unexplained frequencies appear in the vibration spectra, then it would be advisable to have a look at both the current waveform and the existing spectrum. In the web pages that follow, a few examples of problems discovered in DC drives and motors are presented.”
It started with hydraulic fluid couplings producing 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.
Variable Frequency Drives (VFD) were developed and, at the same time, the cost of the shaft trains improved, and so did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and kept VFD out of several applications.