On 2008-10-28, jw wrote:
On Oct 27, 1:38*pm, "Karl Townsend"
wrote:
I put my VFD in the access panel right below the lathe apron. IIRC, that's
where the MG sat. its been over 10 years.
I put a pot on the original speed dial for speed control. And took three
wires from the forward/off/reverse rocker bar to the VFD for on/off/reverse
control. That way, my machine uses all the original controls.
You'll LOVE a 10EE with new speed control. I used a 5 hp. motor and kept the
old backgear. If I were to do it over I'd go with a 10 horse and sell the
backgear on eBay. Which way are you going?
Karl
I was going to use a pot on the speed control and the original FWD/REV/
OFF switch. Mine has 5 wires coming off from it, but for the life of
me, can't figure out what two of them are for. The three black wires
are the FWD/REV, DP contact set. There are two yellow wires that I am
not sure.
O.K. What kind of switch is it?
If a "drum" switch, with a lever moving from "REV" to "OFF" to
"FWD", and a three phase motor, you should expect three wires in, and
three wires out and the switch (with line three phase, not with the VFD)
goes between the line and the motor. One line is simply set up for
"CONNECT/OPEN/CONNECT", while the other pair are set up to be straight
through in forward, and swapped in reverse. But this is six wires. And
you can use one of thet swapped input wires as the COMMON for the VFD
and the two swapped motor phase wires to go to the FORWARD and REVERSE
control points on the VFD.
However -- if there were big contactors to switch the motor from
FORWARD to REVERSE, and you have a set of pushbuttons (in whatever
order) you can expect A common between the two FORWARD and REVERSE
pushbuttons, and a separate FORWARD and REVESE wire from NO (Normally
Open) contacts, and another pair of wires for the STOP pushbutton, which
will be NC (Normally Closed). The VFD should be capable of being wired
to use this arrangement too. Just read the manual.
I have a 7.5 hp on the VFD for now. It seems to have pretty good
torque all the way down to almost stalled (1Hz).
Yep -- but run it too long at those speeds and it will overheat
-- unless you have an external fan which runs full speed all the time.
The motor's own fan is just not moving fast enough to cool itself.
I don't have it
mounted rigidly yet. Just sitting on blocks with it's own weight for
belt tension. This way I can still make things (to repair itself). I
have thought about mouting the backgear on the motor so I could still
keep reasonable power down to nearly nothing. See how it goes I
guess. So far I have nearly no money invested in the retrofit.
Scrounged and donated parts from salvage.
I have a 10HP VFD, and it is too tall too fit behind the panel on the
front side (by the operator) where the MG sat. I could lay it on it's
side. It wouldn't be quite proper for cooling, but it may be ok any
how. It has a fan on it, and would blow sideways instead of upwards.
O.K. As long as the fan does not die. :-)
Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. |
http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---