It is a fact. The cure in your case is a reactor mounted at the VFD and
wired in series with the motor feeder. Top quality industrial motors can
usually handle the max. spike voltage, so spike protection is not so common
in industrial applications unless the motor is inaccessible or difficult and
time consuming to replace. Does this apply to you? BG. The reactor
should be available from the VFD manuf. as an accessory. Everything down
stream of the reactor will be protected, so your standard downhole cable is
OK.

Do you know for a fact that your VFD will run on single-phase power? Some
are internally protected from phase loss and automatically trip off when a
single-phase condition occurs.

Randy



"Karl Townsend" remove .NOT to reply wrote
in message nk.net...
...
have any suggestions? One other thing - it is said that long runs of
wire
from the VFD to the motor can cause problems with motor insulation
breakdown, as the voltage spikes from the switching of the transistors
in the VFD cause damage to the insulation. Unless this is a shallow
well (I don't remember) that would mean long lines to the motor. Does
the pump maker have any comments on using VFDs to run their pumps?
(I'm assuming a submersible well pump, if not, then ignore this last
bit.)
...

I'm totally on my own here. Pump manufacturer says to only use 440 3 phase
directly from the power company. I haven't got that. I know just a three
phase motor-capacitor bank setup (to generate 3 phase) will have trouble.
Can't bring in a 30 hp motor under full load with my 200 amp 1 phase
service - the volts will drop like a rock and trip everything. Don't know
if you know this, but large pumps are actually WAY overloaded at 0 head
pressure, they move too much water. The VFD is just for the soft start
ability.

There's risk no matter which way I go. Now, I've not heard of the voltage
spike issue. Is this rumor or fact? My motor leads will be 225 feet down
the
hole. Anyplace I can go to investigate this problem? I'm thinking special
wire would be prudent.

Karl