starting a 1 HP well pump with a VFX3648 [RE-wrenches]

Sun Jan 28 18:45:18 PST 2007

Standard well pumps are designed to deal with what we would consider
incredible voltage drops.  If you can't find any manufacturers charts online
then call a pump supplier and ask them to look at their chart for you.  They
likely won't be able to tell you % drop as their manufacturer supplied
charts usually just give them how many feet of a given size of wire on
varying sizes of pumps.  I think you'll be amazed, I was.

That being said, I'd be surprised if AC voltage drop on the pump side is the
problem.

Double check but I'm pretty sure Outback is limited to 50 amps for 5 seconds
then it goes into error mode.  My 1hp 240vac well pump needs 27 amps to
start and runs at 9-10 (obtained using a Fluke 337).

I fought and fought a customer's 1 hp 3 wire set up on VFX3624.  The start
winding in the pump wasn't engaging reliably.  Strangest thing since it
would work most of the time.  The start winding by itself is just a few amps
(5, I believe) as it's purpose is to get the pump spinning but if it doesn’t
work then I guess the "run" windings see a locked rotor.  After they
replaced the pump, problems went away.

Best,
Travis Creswell
Ozark Energy Services

-----Original Message-----
From: Darryl Thayer [mailto:daryl_solar at yahoo.com] 
Sent: Friday, January 26, 2007 3:22 PM
To: RE-wrenches at topica.com
Subject: RE: starting a 1 HP well pump with a VFX3648 [RE-wrenches]

Hi Kurt and Todd
Yes I agree with Kurt, volt drop in the wire is very
important,  Measure the running amps, look up the wire
size, look in NEC Chapter 9 Table 8 and find the wire
size--ohms/1000 feet and calculate the volt drop VD= I
x ohms/kft x (total ft round trip)/1000, This should
not bemore than 3 or 5%

As to capacitor size, we always put a larger capacitor
on a hard starting motor.  (there may be some trick in
regards to the inverter that I am unaware of however.}

Caution  Caution I have not tried this on a pump.  
For far out ideas, I have heard of putting a resistor
in series with the motor or the "Run" winding on a
time delay on start relay, The time delay adjusted to
about 1 sec or less and the resistors for the start
current of about 2 ohms (assuming 1 hp and NEC sstart
current as given NEC Table 430.251(A)  I can do this
in the shop with an unloaded motor, works fine, but a
pump is a different matter.  I hope if this has merit
some other wrenches have tried it.  
--- Kurt Nelson <sunwise at cheqnet.net> wrote:

> 
> Hey Todd,
> 
> I don't know the circumstances with this well, but I
> find well drillers
> here in WI consistently undersize the current
> carrying conductors on
> these pumps.  
> 
> What's the distance from the pump placement in the
> well all the way to
> the breaker box and what size wire did they install?
>  You can usually go
> to the pump manufacturer's web page and view a PDF
> of cable sizing for
> their pumps.
> 
> And if you're using a transformer, and if there's
> any real distance from
> the inverter to the transformer, remember this wire
> is carrying twice
> the current on the 120vac input as the 240vac
> output.  
> 
> Kurt
> 
>
----------------------------------------------------------------
> 
> Kurt Nelson
> PO Box 309
> Cornucopia, WI 54827
> 715-742-3406
> sunwise at cheqnet.net
> 
> 
> -----Original Message-----
> From: Todd Cory, Mt. Shasta Energy Services
> [mailto:toddcory at finestplanet.com] 
> Sent: Friday, January 26, 2007 12:54 PM
> To: Wrenches
> Subject: starting a 1 HP well pump with a VFX3648
> [RE-wrenches]
> 
> 
> Wrenches,
> 
> I have an off grid customer with a Outback VFX3648.
> They have a 3 wire, 
> 1 HP well pump that is on the hairy edge of
> operating, occasionally 
> overloading the inverter on startup. I have thought
> about the possible 
> easy solutions to this problem. One is a suggestion
> I have heard from 
> wrenches about changing the starting capacitor on
> the pump's starter. 
> Does this work and if so does anyone know which way
> to go (larger mfd or
> 
> smaller)? Also is there an after market "soft start"
> unit that could be 
> put on this pump? Any other options / suggestions
> would be appreciated.
> 
> Thanks,
> 
> Todd
> 
> 
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