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Posted by Richard Ferguson on May 2, 2006, 10:19 am
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Someone is offering a Quincy compressor at a reasonable price, but he is
not sure if it is single phase or three phase. I need single phase. The
tag on the motor does not seem to help (he emailed me a close-up photo).
It is dual voltage, 208-230/460. The problem with the tag is that it
has a bunch of numbers, but they are not labeled as to what the numbers
are. :-(
Could I take an ohmmeter and figure it out? I would guess that a three
phase motor would have equal resistance on all three combinations of the
phases, while a single phase with neutral would have different
resistance, probably low between the two hot leads and higher between
hot and neutral. Green should be open relative to all the other wires,
no matter the phase count.
Is there another solution?
Richard
--
http://www.fergusonsculpture.com
Sculptures in copper and other metals
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Posted by Ignoramus5749 on May 2, 2006, 10:31 am
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On Tue, 02 May 2006 14:19:44 GMT, Richard Ferguson
> Someone is offering a Quincy compressor at a reasonable price, but he is
> not sure if it is single phase or three phase.
Such people often present good buying opportunities (unless they lie
about what they do not know).
> I need single phase. The tag on the motor does not seem to help (he
> emailed me a close-up photo). It is dual voltage, 208-230/460. The
> problem with the tag is that it has a bunch of numbers, but they are
> not labeled as to what the numbers are. :-(
Most likely 3 phase, considering the voltage. I suspect that you are
missing the phase tag, it is likely to be there somewhere, maybe it
says "PH 3".
What is the HP rating?
A single phase compressor motor usually has a "hump" or two, that hold
capacitors. If you see a motor that is round, without a "hump", it is
likely 3 phase.
> Could I take an ohmmeter and figure it out? I would guess that a three
> phase motor would have equal resistance on all three combinations of the
> phases, while a single phase with neutral would have different
> resistance, probably low between the two hot leads and higher between
> hot and neutral. Green should be open relative to all the other wires,
> no matter the phase count.
>
> Is there another solution?
Another solution s to buy it and then install a single phase
motor. Figure $90 for 3 HP, $170 for 5 HP.
What is the HP, age and price of this compressor?
i
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Posted by Grant Erwin on May 2, 2006, 10:42 am
Please log in for more thread options Richard Ferguson wrote:
> Someone is offering a Quincy compressor at a reasonable price, but he is
> not sure if it is single phase or three phase. I need single phase. The
> tag on the motor does not seem to help (he emailed me a close-up photo).
> It is dual voltage, 208-230/460. The problem with the tag is that it
> has a bunch of numbers, but they are not labeled as to what the numbers
> are. :-(
>
> Could I take an ohmmeter and figure it out? I would guess that a three
> phase motor would have equal resistance on all three combinations of the
> phases, while a single phase with neutral would have different
> resistance, probably low between the two hot leads and higher between
> hot and neutral. Green should be open relative to all the other wires,
> no matter the phase count.
>
> Is there another solution?
Generally you can look at the motor itself. If no bump on the side it's 3 phase,
if there's a bump on the side for start cap; single phase. Another real good
clue is the number of wires in the pigtail. 2 wires -> single phase; 4 wires ->
3 phase, 3 wires is indiscriminate but you can check to see if any have very low
ohms to the motor case; if so you can assume that it's a ground wire and thus
there are 2 hot wires so single phase.
Looking a slightly different way; if you buy the machine and guess wrong, you
then have to find a motor of the correct size and you may have to upgrade the
controls. Motors are generally pretty available at varying cost (I got a 5hp
Leeson single phase motor brand new for my Quincy compressor) but the real cost
killer is if you have to upgrade the mag switch, that can cost you several
hundred dollars if you aren't careful.
Grant
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Posted by Ignoramus5749 on May 2, 2006, 10:50 am
Please log in for more thread options > Richard Ferguson wrote:
>
>> Someone is offering a Quincy compressor at a reasonable price, but he is
>> not sure if it is single phase or three phase. I need single phase. The
>> tag on the motor does not seem to help (he emailed me a close-up photo).
>> It is dual voltage, 208-230/460. The problem with the tag is that it
>> has a bunch of numbers, but they are not labeled as to what the numbers
>> are. :-(
>>
>> Could I take an ohmmeter and figure it out? I would guess that a three
>> phase motor would have equal resistance on all three combinations of the
>> phases, while a single phase with neutral would have different
>> resistance, probably low between the two hot leads and higher between
>> hot and neutral. Green should be open relative to all the other wires,
>> no matter the phase count.
>>
>> Is there another solution?
>
> Generally you can look at the motor itself. If no bump on the side it's 3
phase,
> if there's a bump on the side for start cap; single phase. Another real good
> clue is the number of wires in the pigtail. 2 wires -> single phase; 4 wires
->
> 3 phase, 3 wires is indiscriminate but you can check to see if any have very
low
> ohms to the motor case; if so you can assume that it's a ground wire and thus
> there are 2 hot wires so single phase.
>
> Looking a slightly different way; if you buy the machine and guess wrong, you
> then have to find a motor of the correct size and you may have to upgrade the
> controls. Motors are generally pretty available at varying cost (I got a 5hp
> Leeson single phase motor brand new for my Quincy compressor) but the real
cost
> killer is if you have to upgrade the mag switch, that can cost you several
> hundred dollars if you aren't careful.
>
> Grant
Grant, I respectfully disagree, contactors cost much less than that on
ebay. Example (by far not the best deal)
$15, 5 HP rating at 230v:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7613210040
some used size 2 starters
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7615551695
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7585506953
A lot of new contactors are also sold on ebay.
i
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Posted by Grant Erwin on May 2, 2006, 11:59 am
Please log in for more thread options Ignoramus5749 wrote:
>>
>>Looking a slightly different way; if you buy the machine and guess wrong, you
>>then have to find a motor of the correct size and you may have to upgrade the
>>controls. Motors are generally pretty available at varying cost (I got a 5hp
>>Leeson single phase motor brand new for my Quincy compressor) but the real
cost
>>killer is if you have to upgrade the mag switch, that can cost you several
>>hundred dollars if you aren't careful.
>>
>>Grant
>
>
> Grant, I respectfully disagree, contactors cost much less than that on
> ebay. Example (by far not the best deal)
>
> $15, 5 HP rating at 230v:
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7613210040
>
> some used size 2 starters
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7615551695
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7585506953
Absolutely, no question. However, go buy the right coil and enclosure for any of
those units and you could easily add another $200. I'm speaking from experience
here. I got a Quincy horizontal 2-stage compressor with an ancient 3hp 3ph motor
on it, controls all for 460V. Now a 460V mag switch controlling a 3hp motor is
not very big, plus it had a 460V coil. I wanted the full air output from the
machine, so I wanted to upgrade to 5hp, plus I wanted to switch to single phase
in case I ever wanted to resell it. I found a nice Furnas NEMA size 2½ contactor
for a reasonable price (like one of the prices you cite), bought it, went and
bought a motor, then realized I needed a coil, an enclosure and an AUTO/OFF/HAND
switch, all to fit the Furnas contactor. The tab for those 3 items? Nearly $200!
Sometimes the devil is in the details, and I'm not trying particularly to be
right at all costs here, I just am suggesting that one be fully cognizant of all
the potential costs before starting on a motor swap & reconfiguration.
GWE
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> not sure if it is single phase or three phase.