Was post#9 relevant to your design?
Variable Frequency Drive for Dust Extractor Fans
- Thread starter vinnygalbo
- Start date
- Status
Was post#9 relevant to your design?
- Location
- Massachusetts
Sahib, why do you also post as Haji?
Why do you think so?
Without knowing where it was installed I can't tell.
It surprises me a bit that Tony S posts the ratings as HP rather than kW.
Tony S
Senior Member
- Location
- Resting under the Major Oak UK
Unless your German I doubt it.
Tony S
Senior Member
- Location
- Resting under the Major Oak UK
I'm old fashioned and so was the machinery.
A conventional Kramer then.
VFD typically rated in maximum current output......
Not in my experience - but what would I know about it..............
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Technically true from a design standpoint, but we typically describe them based on the motor they will be connected to, so if the motor is rated in HP, we describe the drive as being that HP. Same for kW. Technically, it can end up getting you in trouble, because motors with high pole counts tend to have higher FLC ratings that standard 2 or 4 pole motors, so I always caution people to start with a HP rating for a drive, but finish the selection when you KNOW the motor FLA and buy the drive based on that FLA.
That said, when you get into the 2200HP range, it's usually medium voltage where the power device ratings are generally such that a few amps either way rarely makes much difference.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
most I see are rated for kW, HP, voltage, frequency and current.
A British VFD may control an American motor at higher speed, higher power but at substantially same current. So VFD rated at maximum output current and not at motor shaft power.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Only if the input voltage to the drive is high enough to support the increase. Most drives these days can operate at a fairly wide range of voltage with the same output current. You can't put a US motor on a 400 VAC system and get any more HP out of it than if it was an IEC rated motor.
So the KW rating of the VFD is not always applicable as it is not same at 460V and at 400V. But its maximum current output is.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Technically true, but pointless to argue about. When I am buying a VFD, I am buying it for MY applicable voltage. Why the heck would I care what it's rating is at 400V? I DON'T HAVE 400V here. It's kW rating at 400V is just another useless piece of information clogging up my data sheets as far as I am concerned. And the same would be true for you, Besoeker and Tony with regard to a 240V or 480V HP rating. Why the heck would you care?
But for ALL of us, if we have to calculate Amps every time from a motor rating (in kW or HP) in order to pick out a VFD, it's a royal pain during the heat of battle. So we pick them out based on the motor rating, again kW or HP as presented to you in your location. Then as good Engineers, we cross check against the motor nameplate FLA once that is known before allowing anyone to sign a Purchase Order.
- Location
- Massachusetts
Give Sahib / Haji a break, it is hard to find a way to screw up so many threads with nonsense.
You are correct for local business of VFD products. But for global business such as mentioned in this article:
http://www.moeller.net/binary/ver_techpapers/ver964en.pdf
current rating is mentioned as criterion for selection of VFD's as mentioned in pages 9 to 11 of the above article.
Stupid, taken so long to realise.it is hard to find a way to screw up so many threads with nonsense.
Tony S
Senior Member
- Location
- Resting under the Major Oak UK
Make a simple comment about resonant vibration and it turns in to The Spanish Inquisition.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Which was unexpected, of course.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
There is a comic element in that skit that I love and use to this day.
The element is when he says "Our chief weapon is surprise... and fear.Our TWO chief weapons are surprise and fear... and a fanatical devotion to the Pope.Our three chief weapons..." I had forgotten where I got that, thanks for reminding me!
I have done this in presentations where I'm supposed to extol some virtues of whatever our salesmen are selling, and it's a very dry boring subject with people who are there mostly for the free lunch. It gets them laughing, which holds their interest better. I just had a meeting like that today and I didn't do it (because my boss was in the room and he has no sense of humor), but one of the Consultant EEs in the room had been to one of my "Lunch and Learn" meetings before and was actually expecting it. He even said something afterward.
The element is when he says "Our chief weapon is surprise... and fear.Our TWO chief weapons are surprise and fear... and a fanatical devotion to the Pope.Our three chief weapons..." I had forgotten where I got that, thanks for reminding me!
I have done this in presentations where I'm supposed to extol some virtues of whatever our salesmen are selling, and it's a very dry boring subject with people who are there mostly for the free lunch. It gets them laughing, which holds their interest better. I just had a meeting like that today and I didn't do it (because my boss was in the room and he has no sense of humor), but one of the Consultant EEs in the room had been to one of my "Lunch and Learn" meetings before and was actually expecting it. He even said something afterward.
- Status