The three horse motor on my compressor died. I've had this big 5.5 hp
Marathon for just such an occasion. It is 230v 1ph 215T frame (if that
I've downloaded Marathon's installation and operation manual. Under
changing rotation, it says follow the diagram on the motor. Surprise,
surprise. No diagram. All wires are numbered. It is currently running
Any help from the gallery? I have new breakers! :)
On single phase motors you basically have two windings. One is the starting
the other is the running winding. *IF* there is a capacitor it will usually be
Anyway, check all your leads and let us know what they are. There is probably a
letter on each of them. Someone can probably tell you from the numbers /
letters you provide.
Now, to your question. Usually, all you have to do is reverse the two leads on
STARTING winding. That takes care of it. ;-) You just have to figure out
which two are
the right ones.
I'm assuming it is a single voltage and you have two groups of 3 wires, one
electrical line feeding the other two. One running winding and one starting
attach to each of the power lines. Again *if* you have numbers like S1 & S2
those two. But I'm not sure what labels you'll have - if any.
Hope this helps.
If the motor is an induction motor and single phase, rotation often can be
changed by reversing the armature end for end. This is especially true with
centrifugally switched, shaded pole starting. Swapping the wires on the
start capacitor will not change the start direction on capacitor start
motors. Reversing single phase motors have two start windings, one for CW
and one for CCW. Direction is determined which start winding is engaged with
a switch. Motors that have only a single start winding can only be reversed
by rotating the run field winding. This can only be done if the end plates
On Wed, 21 May 2008 08:12:10 +0200, "Steve Lusardi"
This advice has got a bit garbled.
Single phase SHADED pole motors have no accessible
start windings (they are the short circuited copper rings). They
are sometimes (rarely) fitted with two MAIN windings - one for
each direction. The construction normally permits direction
reversal by mechanical 180 deg rotation of the stator with no
change of the rotor shaft connection to the load
If the rotor is reversed end for end and the drive taken
from the previously unused rotor shaft end the drive direction
will remain unaltered. This is also true for single and three
phase induction motors.
Single phase motors with split phase or capacitor start
have a main winding and a smaller start winding. Rotation can be
reversed by reversing the connections to either (NOT both) the
main or the start winding. Once the motor is up and running the
start winding is no longer connected so running reversal is not
A 5.5HP motor is almost certainly capacitor start or
capacitor run. To reverse you need to identify the two ends of
either the main winding or the start winding and reverse one of
them. To sort this out we need more information - you need to
post the existing connections to the numbered wires.
It is *only* necessary for the shaded pole starting -- though I
have move the shading rings on clock motors to make them run in reverse.
Agreed -- for the capacitor only.
*No*. At least not for single-phase motors of the horsepower
range needed for machine tools.
For a dual-voltage motor, you have three windings (beware, the
numbers which I have used to label the windings are for my convenience
in describing it, and are not likely to be used on commercial motors):
(1) o-----WWWWWWWWWWWWWWW---------------o (2)
(3) o-----WWWWWWWWWWWWWWW---------------o (4)
(5) o-----WWWWWWWWWWWWWWW---)|-o o------o (6)
Windings (1-2), and (3-4) are the two run windings. winding
(5-6) is the start winding -- with the centrifugal switch and the
To run at the lower voltage, you connect (1), (3), (5), and (L1)
together, and (2), (4), (6), and (L2) together.
To reverse it, you interchange where (5) and (6) are connected.
To run at the higher voltage, you connect:
(L1) to (1)
(L2) to (4)
(2) and (3) to (5)
To select one direction of rotation, you connect (6) to (L1) (1).
To select the other direction of rotation, you connect (6) to (L2) and (4).
No! Only one start winding, two run windings, which are
connected in parallel to run at the lower voltage, or in series to run
at the higher voltage. The start winding is only designed for the lower
voltage, but by connecting one end of it to the junction of the two run
windings connected in series for high voltage operation, you have half
the applied voltage available between that point and either end, and
switching the free end of the start winding from one end to the other is
equivalent to reversing it -- but needs fewer switch contacts to
accomplish the task.
No -- as long as the start winding (with the capacitor and
centrifugal switch) is brought out as its own independent wires, all
that is needed is to reverse either the start winding or the run
winding, assuming a single voltage motor.
And reversing the field can be awkward with a centrifugal
switch, because part of it is mounted on one end of the rotor.
Email: < firstname.lastname@example.org> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
T5 and T8 are the leads to the start winding that controls the
direction of rotation.
Near the end of this article is the most of the information you're
looking for. Look at the diagrams, read the trouble shooting section
at the end.
If you do not have any of the leads labeled you can still reverse the rotation.
ohm meter (anything to check continuity) and determine which leads complete a
a single voltage motor you should only have four wires for the two windings.
In your case reverse either set of wires as it will effectively have reversed
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.