In article WLJIc.38535$Ch.37465@okepread04,
Jake in Escondido wrote:
Thanks for the terrific responses. It looks like I am going to be busy
this Saturday. Now to answer some of the questions.
The Teco unit is new and I picked it up from Dealer's Electric.I have
another Teco unit powering my Mill (no problems). I have run the VFD
into the lathe, contro box, not directly to the motor. I was hoping to
make use of the existing switches and lamps.
*That* is the problem. You *can* continue to use the switches
-- with a bit of re-wiring, to use the switches to command the VFD
directly, and the motor wired directly into the VFD.
I have conneted everything
with about 10 total feet with #10 solid copper wire from the junction box.
The fault happens both at high and low speed. I have been starting the
lathe from the switch below the saddle once the pannel gauge has moved
to 60 hz. I do notice a good bit of chatter from the relays as it
approaches 30 hz. Until I get things running right I haven't set the VFD
above 60 hz. The chuck is a 8" Bison 3-jaw and it isn't lite.
Unfortunately, those relays preclude the simple test. Plug the
VFD in, set to stop. Turn on the motor switch, and then command the VFD
to start. This won't work because of those relays chattering during the
ramp-up -- and may actually do more damage.
Yank the wires from the switches to the motor, connect them
*directly* to the VFD, and see what happens just commanding the VFD to
start and stop the motor.
Once you are assured that this works, yank out the rest of the
wiring, and run the wires from the carriage switch to the VFD's command
terminals. (I think that you'll find the actual switch (or perhaps a
pair of switches) in the left-hand pedestal, and run by a keyed rod
passing through the carriage and the fwd/stop/rev lever.) You can then
also pass the signal through the master switch on the front panel of the
lathe, or (as I would be tempted to do) use that master switch and the
relays to switch the power on the *input* side of the VFD, so you are
assured that the VFD is off the power grid when you are not using the
lathe. (This reduces the chance of a lightning strike accidentally
damaging the VFD in just such a way as to leave it running the spindle
full speed forward or reverse while you are elsewhere.
I have run the start time from 4-12 seconds with no effect.
So it is not ramp-up time that is the problem -- and since you
don't have the motor load present when the VFD is starting, it could not
be the problem. :-) That start time setting only affects how slowly the
VFD ramps up its voltage and current form when *it* is commanded to
start. You're bypassing that entirely.
I couldn't find anything in the manual relating to "overcurrent" could
"Overtorque Control" be what I am looking for?
Your "overcurrent" is when you are switching a halted motor onto
the VFD when it is already producing a standard 60 Hz. So when you stop
"beating your wife", you should not need to worry about the settings.
It would probably be called a "current limit" or something similar.
Each vendor has his own terminology -- I think to make it more difficult
for a customer to move to another brand once they know one brand. :-)
Good Luck,
DoN.
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