Just wondering if this would be a good VFD for a 2 hp 220 3 phase motor?
Or should I get one with a higher rating? (Kw)
Or should I get one with a higher rating? (Kw)
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Tips/Techniques VFD?
- Thread starter Tomc938
- Start date
Tips/Techniques
I had heard people (Dabbler?) saying get more than you think you need, to be safe. Wasn't sure initially what kind of extra needed.
It's a $/safety factor equation. I like the price point on this one.
Hi Tom, have a look at this from Hitachi:
The key parameter - rarely quoted - is the duty cycle. If rated for continuous, then a 2HP VFD can handle a 2HP motor running 24/7/365 with room to spare. Almost nothing is up to this task. Manufactures generally prefer to rate their equipment at a higher level (say 5HP) at a lessor duty cycle. The thing to do, is to buy one of those 'larger' devices, so that the level of work that you do doesn't push it beyond what it really can do. For us hobby users, i would guess that a 1/4 to 1/3 uplift would make sense. So a 4 for 3 or 3 for 2 or there abouts rule of thumb.
I should go to bed.
ABS (Acrylonitrile butadiene styrene) is completely stable up to about 80 degrees Celsius. It is also immune to most ordinary solvents and withstands impact well. At higher temperatures, up to say 400 C, it has amorphous behaviour. Higher than that, it sublimates and produces toxic fumes, but doesn't really burn per se. At this level, the fumes are all toxic and carcinogenic. It's all bad news.
The other features are what would be expected for anything certified by UL /CUL etc.. Actually, they seem to be the same thing restated as three separate 'features' for marketing purposes. I think everyone has seen that way too much. Since BS is anathema to me, so I call it out as i see it.
As an aside, this is the material that Lego bricks are made of
ABS (Acrylonitrile butadiene styrene) is completely stable up to about 80 degrees Celsius. It is also immune to most ordinary solvents and withstands impact well. At higher temperatures, up to say 400 C, it has amorphous behaviour. Higher than that, it sublimates and produces toxic fumes, but doesn't really burn per se. At this level, the fumes are all toxic and carcinogenic. It's all bad news.
The other features are what would be expected for anything certified by UL /CUL etc.. Actually, they seem to be the same thing restated as three separate 'features' for marketing purposes. I think everyone has seen that way too much. Since BS is anathema to me, so I call it out as i see it.
As an aside, this is the material that Lego bricks are made of
Building a wee bit on @mbond's comments, it sometimes helps to think of duty cycle in terms of the application.
A pump is typically a 100% duty cycle. Pumps typically run full load most of the time.
A conveyor belt is similar but might not always carry a full load. However, the fact that it could carry a full load for hours on end means it has to be designed for a 100% duty cycle.
A mill almost never sees its maximum load for hours on end. For the most part they operate well below that. Even during spin up, mills see very little load. There is little to no point in up sizing the motor on a mill.
A lathe is the same except that spin up time is usually a full load exercise for the motor because of the size, weight, friction, and complexity of the drive train. For this reason, it is a good idea to upsize the motor but then limit the actual hp requirements by setting a spin up time that is the same or less than before.
In all cases, it is good to remember that nothing is stronger than its weakest link. In most machines, the weakest link is usually the drive train. Adding a bigger motor doesn't make the drivetrain any stronger. So it's not usually a good idea to add a bigger motor and then go buy bigger tooling too. It is better to buy a bigger machine if you need to use bigger tools or increase production.