More than 50% of the compression and pumping systems over 3 MW need a variable-speed drive. Often medium-voltage motors fed by Variable Speed Gearbox frequency converters and parallel shaft gears are selected. Others are employing epicyclic gears with a hydrodynamic superimposition drive.
Taking advantage of the condition 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) motor and a dynamic Front-End Cycle Converter. Therefore – E stands for Electric.
This 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.
A lot 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 using epicyclic gears with a hydrodynamic superimposition drive.
It started with hydraulic fluid couplings making 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, simultaneously, the expense of the shaft trains increased, and so did efficiency. The issue of THD (Total Harmonic grid Distortion) rose and kept VFD out of several applications.
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 founded on a Long term Magnet Synchronous Superimposition (SI) engine and a dynamic Front-End Cycle Converter. So – 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 situation, the vibration will end up being 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 appear in the vibration spectra, then it might be advisable to check out both the current waveform and the existing spectrum. In the web pages that follow, some examples of problems discovered in DC drives and motors are offered.”
It started with hydraulic liquid 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, at the same time, the expense of the shaft trains increased, therefore did efficiency. The issue of THD (Total Harmonic grid Distortion) rose and kept VFD out of many applications.