A lot 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 selected. Others are using epicyclic gears with a hydrodynamic superimposition drive.
Taking advantage of the state of the artwork in electrical motors and frequency converters, the driving program for the superimposition of the earth carrier is founded on a Long lasting Magnet Synchronous Superimposition (SI) motor and an Active Front-End Cycle Converter. Therefore – E stands for Electric.
This 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.
More than 50% of the compression and pumping systems over 3 MW need a variable-speed drive. Often 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 producing slippage with results very little much better than the throttle.
The look of hydraulic Variable Speed Gearbox 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 improved, and so did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and kept VFD out of several applications.
Taking advantage of the condition of the art in electric powered motors and frequency converters, the driving program for the superimposition of the earth carrier is founded on a Permanent Magnet Synchronous Superimposition (SI) motor and a dynamic Front-End Cycle Converter. Therefore – E means 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.
All of the over plots were taken by analyzing the current to the electric motor. In a normal circumstance, the vibration will become monitored and stored on a periodic basis. If the 360 Hz signal exists in the vibration spectrum, it isn’t normally of any concern. If, however, additional unexplained frequencies come in the vibration spectra, then it would be advisable to have a look at both current waveform and the existing spectrum. In the web pages that 
follow, a few examples of problems uncovered in DC drives and motors are offered.”
It started with hydraulic fluid couplings creating 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, and so did efficiency. The problem of THD (Total Harmonic grid Distortion) rose and kept VFD out of several applications.