The Precision Electric guys are really good. I've been in their motor
rewind shop. I was involved in a re-control job on a paper web line
and they rewound some failing DC motors over Christmas.. they did a
really great job.
They also have a large repair area where they repair drives, servo, VFD,
etc. They knows drives to the component level which is rather rare
these days.
Nothing they do is hobby related. Its all industrial/heavy industrial.
Regarding the $132 price... I agree. Just too cheap. I would avoid.
Les mentioned Yaskawa drives for a reasonable price. They have a very
good reputation and are not normally low priced drives.
Dave
On 1/2/2018 10:37 AM, John Figie wrote:
Dave,
Yes I want a 5hp vfd with single phase input and that is why i am
interested in the gohz GK3000-2S0037 @ $294. On amazon there are some even
cheaper @$132 but there is no on line manual and i don't think a 5 hp
single phase input drive can be made that cheap.
I read the article you referenced https://www.precisi
on-elec.com/derate-three-phase-vfd-for-single-phase-power/ but I don't
agree with it because he is simply scaling the input current by the 3 phase
to single phase conversion constant of square root of 3 or 1.73. This
holds true for the input current but not the internal DC bus capacitor RMS
ripple current which causes capacitor heating.
On the other hand there is a huge difference between occasional hobby use
and industrial use so maybe I shouldn't be so finicky.
John Figie
On Jan 2, 2018 8:03 AM, "Dave Cole" <linuxcncro...@gmail.com> wrote:
Except that he needs a 5 hp single phase inverter. Those are a little
harder to find and a lot more expensive... near $1000 for this AC Tech
Drive.
https://www.wolfautomation.com/products/ac-drives/ac-drive-
5hp-208-240vac-1-3-phase-input
Phase converters do have some phase current balance issues but for low
tech - I just want to run the machine - they are hard to beat unless you
are running the machine a lot or at a constant full load. I have a rotary
phase converter built with a 10hp motor 15+ years ago and it will power a
10 hp Quincy two stage air compressor at slightly reduced pressure. I
probably put about $250 into that phase converter 15 years ago. Good
motor run caps are the key. Those can be bought off Ebay and Surplus
Center, etc.
There is a small down the road that manufactures steel stakes for the Army
Corp of engineers and landscape contractors in large quantities and he has
an assortment of small punch presses and the entire shop runs off single
phase power with a phase converter. So it can be done. Sometimes low tech
is enough and if you don't need variable speed it can work well.
Dave
On 1/1/2018 7:58 PM, Gregg Eshelman via Emc-users wrote:
Or just get a proper single phase to three phase VFD and do the job
right. For under $200 you can get a 230V 1PH in drive that'll run up to a
3HP 3PH
https://www.wolfautomation.com/products/ac-drives
On Monday, January 1, 2018, 10:49:12 AM MST, John Figie <
zephyr9...@gmail.com> wrote:
All,
Thanks for your replies.
My real question was to see if anyone had used GOHZ or some other cheap
drive. I currently run all my machines from a home made rotary phase
converter. It works pretty well but does not produce the best 3 phase.
Yes I know you can use capacitors to adjust the outputs which I have. The
rotary converter has been running in my shop for about 15 years. I have a
hydraulic automatic surface grinder that does n't like being run from the
phase converter. The pump motor overheats when run from my rotary
converter, I think maybe this is because the motor runs near full load.
I know I can use a larger drive and derate it to use on single phase
power,
but that seems like a much more expensive option.<clip>
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