On 2012-01-07, Bob La Londe wrote:
"DoN. Nichols" wrote in message
...
On 2012-01-06, Bob La Londe wrote:
I have a Leland 6273 3 phase 240 V motor I am trying to figure out how to
hook up.
It has 6 black wires coming out of the motor.
[ ... ]
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Hmm ... looking on the web. I find other places where you asked
the same question, and on one you say:
================================================== ====================
The wires are in groups of 3. Any 2 in the first group read
about 20 ohms.
Any 2 in the second group read about 2 ohms.
================================================== ====================
Which suggests that the three which measure 2 ohms are likely the three
phase power input windings, and the other three are perhaps feedback to
some kind of controller other than the standard VFD.
Does it matter which order I hook them up in then? It was my understanding
if you just had the three wires all you had to do was hook them up and if
the motor ran backwards you just swapped any two wires. (unless the VFD has
reversed the motor for you)
That is exactly how it should behave. You pick an order, note
the direction of the spindle (relative to how you want it to turn), and
either mark the three leads with the designation of the terminals which
they connect to (whatever the VFD maker picked), or interchange two,
verify that it now turns the direction you want, and *then* label the
wires. :-)
What happens if
you connect the first three to the outputs from the VFD.
I have not hooked up the VFD or the motor yet. Still doing my homework.
Based on the other suggestions, I believe that it is likely an
internal fan, designed to keep it cool when running at low speeds, where
a fan on the motor's rotor and shaft would not turn fast enough to
cool things properly.
I just got through posting (elsewhere in this thread) a way to
test this with your VFD, and some starting suggestions on how to run it
from the single phase if it is a fan. Remember -- the fan likely wants
three phase at 60 Hz to run properly, and you will have to fake that,
since your VFD will be producing much lower frequencies part of the
time.
Then you try the low resistance set, and expect the motor shaft
to turn.
All I did today was setup a 240 V disconnect with a short 10 gauge cord and
a locking plug, then installed a receptacle with a matching outlet. That
circuit was intended for my future air compressor, but it will work for this
for now.
I agree. The VFD will draw a sharp spike of current when it is
first connected -- to charge it's big DC capacitors.
Oh, I did also order a frequency meter to hook to the VFD for
testing. I couldn't find my old Radio Shack meter with the frequency
counter.
I would suggest not expecting anything reasonable from the
frequency meter. A VFD does not produce clean three phase sine waves,
but instead takes the full voltage from the internal capacitors (usually
1.414 times the input voltage, unless it is playing at being a voltage
doubler too, like those for operation from 120 VAC.) It then uses the
output MOSFETs or IGFETs to switch that on and off to the output. It
will start a phase by turning on the full voltage for a tiny amount of
time and then back off (to produce the effect of a very low voltage,
though it will in reality be quite high. Then it will turn it on again,
a bit longer, to pretend to be a voltage a little more along the curve,
and keep doing that until it keeps it on almost full time to pretend to
be the sine wave at it's peak, and then start getting narrower. It
will, once it reaches zero, start switching back on the same way to a
negative voltage, and go through the same sequence until the other half
cycle is completed. This is for one phase. The next phase goes through
the same pattern, a little later in the cycle, and the third does the
same again, still a little later, so they three are equally spaced.
This high frequency series of high voltage pulses are what the
frequency meter will most likely see -- if the voltages don't burn it
out immediately.
If you want to see the frequency, configure the VFD to display
it for you. :-)
(This is
assuming that both sets of wires are the same gauge.
They are the same gauge.
Likely fan for the high resistance, and motor for the low.
(Pending you getting in contact with the maker and finding out what is
*really* there.
Someone else suggested that you take it apart to see. Maybe or
maybe not. Depends on how difficult it is to take apart.
And if the two small gauge wires measure near 0 Ohms, it is
likely a thermal switch, and you want to wire it into the VFD in such a
way that it says *STOP* when it opens, to keep the magic smoke from
getting out of the motor. Put it in series with the Stop button, if
that is how you wind up configuring the VFD.
If the ones to the
20 Ohm wires are heavier, apply power to those instead, but at 5 HP, I
doubt that this will be right. If it as I now believe, just cap each of
the 20 Ohm wires to protect them from shorting into anything.
What do you think about the thought that it might be a two speed motor?
Highly unlikely -- with that wide a range of resistances.
Good Luck,
I'll probably use a momentary switch for the start switch on the VFD for
testing, and keep a fire extinguisher handy.
Disconnect first, fire extinguisher *soon* after there is no
power. :-)
I need to pick up a 2w 1k POT
for frequency control for now too. The VFD will be setup with 0-10 VDC
control eventually, but for now its going to be setup for variable
resistance control.
The same 2K pot should work with voltage control too. The VFD
should have a 10V output to drive the pot.
Good Luck,
DoN.
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