VFD's

A_G

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Jul 2014
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I know I should already know this but I just started a new job and I am confused on something. My boss is calling every drive a VFD. I thought AC drives are the same thing as VFD's but DC drives are not. Any help to understand this is appreciated!
 
Your boss is ill informed. VFD stands for variable frequency drive. A DC drive is not a VFD. Considering you're new I would refrain from correcting him.
 
A variable frequency drive (VFD) refers to AC drives only and a variable speed drive (VSD) refers to either AC Drives or DC Drives. VFDs vary the speed of an AC motor by varying the frequency to the motor. VSDs referring to DC motors vary the speed by varying the voltage to the motor.

Regards,
 
The term drive is a genetic term that covers a very large area
I like the phrase drive system to cover the range from power source to point of useful machinal work. includes if applicable but not limited to VFD's, DC Converters, soft starts Eddie current drives Brushless DC Drives gear reducers and pullies and shives
VFD is a Variable Frequency Drive. A lot of people won't know or care to know all the differences so it's just as easy to call them all drive's. Every body knows what the are talking about you get use to it.
 
It used to be VSD and ASD as the more generic terms that included AC and DC drives (variable speed, adjustable speed...).

I had a boss who called them all "inverters". I didn't bother to point out to him that the inverter section is arguable only 1/3 of a "drive".

Heck I have even seen web pages for VFD manufacturers refer to their own products as inverters. I am sort of a stickler for detail and accuracy when it comes to words and text coming from engineers and product manufacturers, but from co-workers, especially those who outrank me, you gotta sometimes let things slide.
 
Before the widespread advent of solar systems, the term "inverter" was less vague. Now someone may not know which "inverter" you might be referring to.


I too hear people referring to anything that changes a motor speed as a "VFD". I am the type that corrects them, some people appreciate hearing it, others don't like that about me...
 
Thanks I knew this site would help me get to the bottom of it
 
Drive could mean DOL starter though..

Is there a Standard for this sort of thing?

There are perhaps a number of problems to resolve:
Things blatantly being called the wrong thing, such as a "Variable frequency drive" when the frequency doesn't change.
Only describing part of the functionality, such as "inverter"
Over describing something, like saying "I need a level controller" when you only need a level display.
Trying to procure something when different companies call it different things.
 
I choose to let people call things what they want and learn what they mean. It is no skin off my back. That being said, i'm very specific and don't often mince my words when taking shop or speaking about something.

As a side note, I refer to them all as drives and use the motor and system as context. If i'm ordering a part, I know what I want.
 
Variable Voltage, Variable Frequency Drive - technically more correct than just "VFD" I suppose.


My sentiments, with credit to xkcd:
i_could_care_less.png
 

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