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 Variable Speed Gearbox parallel shaft gears are selected. Others are using epicyclic gears with a hydrodynamic superimposition drive.
Taking advantage of the state of the artwork in electric motors and frequency converters, the driving program for the superimposition of the planet carrier is based on a Long 
lasting Magnet Synchronous Superimposition (SI) engine and a dynamic Front-End Cycle Converter. So – E means Electric.
That 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.
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 fluid couplings making 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.
Variable Frequency Drives (VFD) were developed and, at the same time, the cost of the shaft trains increased, and so did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and held VFD out of several applications.
Taking advantage 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 Permanent Magnet Synchronous Superimposition (SI) engine and an Active Front-End Cycle Converter. So – E stands for Electric.
That is a high-speed gear drive system incorporating components that allow the usage of a low-cost constant-speed (electric) driver for a variable-speed application.
All of the over plots were taken by analyzing the existing to the engine. In a normal circumstance, the vibration will end up being 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, other unexplained frequencies come in the vibration spectra, then it would be advisable to check out both the current waveform and the existing spectrum. In the pages that follow, some examples of problems uncovered in DC drives and motors are shown.”
It started with hydraulic liquid couplings generating slippage with results very little 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, at the same time, the cost of the shaft trains increased, and so did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and held VFD out of many applications.