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[email protected] etpm@whidbey.com is offline
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Default Compressors - kinda on topic !

On Tue, 4 Dec 2018 07:39:25 -0600, Terry Coombs
wrote:

On 12/4/2018 6:43 AM, Leon Fisk wrote:
On Mon, 3 Dec 2018 13:53:29 -0600
Terry Coombs wrote:

* Well , Mr. Compressor has a case of the humms . That is , when I try
to start it , it just humms (until the O/L cuts it off if I let it go
that long). This is the original motor on an old Speedaire 60 gallon
tank , 220 volts and 3450 RPM's . Specs call for 15 amps full load ,
rated output is 2.98Kw , about 6 hp . This is an Emerson/Doerr
compressor duty motor .* Tested both caps , one is good and the other
isn't according to the tests with my DMM . Problem is that the bad cap
has rubbed the capacitance and voltage ratings off the label . Got a
couple of calls in , looked around on the internet , can't find a
definite answer . I'm pretty sure it needs to be around 250uf and at
least 250 volts - though maybe higher voltage to account for spikes . I
have the motor type/classification numbers , just can't find a reference
to check ... anybody got a lead on that type of info ?


I had a similar problem a few years ago with my Speedaire 20 gallon
2hp. My caps checked out. Ended up cleaning the contacts on the
starting/centrifugal switch. Has been okay since. Take a look at this
pdf file and see it it lists your motor:

https://www.jackssmallengines.com/gr...PREADSHEET.pdf

It had mine in it plus quite a few more...

* Thanks Leon , my motor is listed ! For a 606727 motor - that's what
is on my tag - it calls for a 704 mfd at 110 volts . Hmmm , that doesn't
seem right since this is a 220 volt motor . If doubling the voltage
halves the capacitance needed , a 330-380 mfd cap would seem about right
... I just found a contact link for Emerson , messaged them . We'll see
what they say . I never really thought about how much I use that
compressed air until I don't have it ... and since my ne'er-do-well son
has apparently burned up my small portable for me , I'm kinda in a pinch .

The cap in your motor is only connected across one line and neutral,
that's why the 110 volt rating. The very high capacitance is because
the motor is a compressor rated motor and needs the extra torque. I
just went through all this a couple months ago. You really need to
check the starting switch. I guarantee it is easier and cheaper to
replace it with a motor starter if it is the problem. The phenolic
support for the switch in my motor warped which is why I opted the
replace it completely. Electric motors don't usually wear out unless
the windings are really stressed by high current, high voltage, high
temp operating conditions, moisture, etc. Bearings and starter
switches are what usually dies in a single phase electric motor. If
you do decide to replace the motor make sure it is rated for high
torque loads and check the shaft size. Ther is a good chance your
motor has a 25mm shaft, not 1 inch.
Eric