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 chosen. Others are using epicyclic gears with a hydrodynamic superimposition drive.

Taking benefit of the condition 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) electric motor and a dynamic Front-End Cycle Converter. Therefore - E stands for Electric.
This is a high-speed gear drive system Variator Gearbox incorporating components that allow the utilization of a low-cost constant-speed (electric) driver for a variable-speed application.

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 employing 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, 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 many applications.

Taking advantage of the state of the art in electric motors and frequency converters, the driving system for the superimposition of the planet carrier is founded on a Permanent Magnet Synchronous Superimposition (SI) motor and a dynamic Front-End Cycle Converter. Therefore - 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 current to the motor. In a normal circumstance, the vibration will become monitored and stored on a periodic basis. If the 360 Hz signal is present in the vibration spectrum, it isn't normally of any concern. If, however, additional unexplained frequencies appear in the vibration spectra, after that it might be advisable to take a look at both the current waveform and the current spectrum. In the pages that follow, a few examples of problems discovered in DC drives and motors are presented.”
It started with hydraulic fluid couplings generating 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 increased, therefore did efficiency. The issue of THD (Total Harmonic grid Distortion) rose and held VFD out of several applications.