Variable Speed Drives and Frequency Inverter

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Tecnicas y Tecnicas

Please can someone explain to me what is the difference beteween the function of - Variable Speed Drives and a Frequency Inverter

Gustavo R

Mark Sevelis

I assume both terms refer to motor drives...

1) "Adjustable" and "Variable" are synonymous in their meanings.

2) VSD varies o/p frequency by "inverting" a DC voltage (bus voltage) into a three-phase PWM signal that allows an ac motor to be varied
between 0-60 Hz or more. The ac motor is "tricked" into thinking it sees a sine wave voltage.

3) An ASD or VSD is commonly referred to as an inverter. The section within the drive (described in 2) is the actual inverter.

Regards. Mark Sevelis Allen-Bradley Standard Drives Tech Support.
Generally in an inverter drive system which includes an inverter and motor combination and the system that gives control parameters such as a PLC, forexample, the inverter part converts DC input into AC output of desired voltage at a desired frequency(hence called frequency inverter). but there is a limit to which the voltage and frequency can be controlled. By controlling the frequency, we can control the speed of the motor which varies directly proportional to the freq. Hence it is called variable speed drive.
This is the first time I am visiting this site and I don't know if you guys are always talking about automation only. Could Mr Gustavo be
thinking about mechanical variable speed versus Frequency invertion ? The terms used are the terms we use in my company for the above. BR