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Questions on Single Phase VFD for well pump

J

John Gilmer

Jan 1, 1970
0
Sorry it took so long to get back, I was busy elsewhere.

Your reply is worth the wait!
That pump originally came with a Franklin submersible motor.
Franklin's standard design is split phase cap-start / cap-run, with
the caps being external to the motor in a "control box". In one of
your early posts I thought I read that someone had "modified" yours to
no longer need the external caps.

No modification. The failed unit had the control box with the capacitor
and the current sensing relay.

The replacement unit was just 2-wire.
That means that they probably
changed it to Franklin's "2 wire" design, which means that the
starting components are integral to the hermetically sealed motor, but
it is still a split phase design with a start switch, so you will NOT
be able to use a VFD on it, they will not work and you will damage the
VFD and/or the caps.

So you are saying that there is some kind of switch build into the pump
that's sitting in the lubricating oil? Do they have a capacitor down there
too?
For future reference, the best 1 phase VFD out there right now is make
in the UK by Invertek, but is sold in the US by Bardac
(www.bardac.com) and Anacon (www.anacon.com). Again, only if it is a
PSC motor.

When you use a VFD you no longer need to worry about "short cycle"
protection because the VFD does not stress the motor windings on
startup. Still, there is probably something like that in the Invertek
drive, I just have never used it.

Yes, all VFDs will retain all of their memory after a power failure.

An option for you is to replace that motor with a 3 phase version,
then get a VFD with a 1 phase input / 3 phase output. Check out
Frankiln at http://www.franklin-electric.com/Prod_text/item1.htm
Then you can get any inexpensive 1HP 230V VFD and use it as a phase
converter. I recommend the Teco FM50 for low cost and reliability.

Well, the pump only has a 5 year guarantee. With all that stuff down there
waiting to fail I doubt that I will get 30 years of service out of it.
 
J

John Gilmer

Jan 1, 1970
0
I check our your URLs.

"They" put a lot of stuff down there. I don't know if my model has it, but
some of those motors, it seems, will detect if they are jammed with sand and
run backwards to try to clear things out!

Simply amazing!
 
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