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

Darryl Thayer daryl_solar at yahoo.com
Fri Jan 26 13:21:47 PST 2007


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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