Introduction: REPULSION START.....INDUCTION RUN MOTOR
A large cast iron ( 12" jaw ) wood planer powered by a Repulsion-Start Induction-Run motor.
This is a class of motor that overcomes the induction motor's low starting torque
and incorporates the large starting torque,
while loosing the noise and brush wear of a repulsion motor.
For those who are not interested in the speed torque can skip the next step.
Curious about IRON PENNIES well you are in luck.
Step 1: THE NEED... THE NEED............. FOR TORQUE and Speed
The starting of a large Planer takes more toque then an induction machine can provide
in accelerating the mass of the single edge blade in a massive flywheel.
The first graph ( Third Pic ) plots the speed torque of a repulsion motor
which has a strong starting torque at low speed.
See the ( First Pic ) a simplified repulsion motor wiring diagram.
After 40 seconds the repulsion motor reaches speed and the brushes lift off the
commutator turning the motor into an induction machine for planing.
Here is a pointer to an actual repulsion motor starting a planer wind-up
that you can see and hear.
See the ( Fourth Pic ) a simplified Induction motor wiring diagram.
The second graph ( Sixth Pic ) plots the speed torque of a Induction motor
which has almost no starting torque at all ( used for fans )..
Step 2: BIG CAST IRON PLANER
IF you skipped here from the Introduction you may want to use this pointer to see and hear
an actual repulsion motor wind-up sound starting this planer.
A safety cover blocks access to the very dangerous spinning steel cutting flywheel blade.
Step 3: WHATS a REPULSION MOTOR
As you can see the repulsion motor uses stationary brushes on the rotor
with attached commutator to achieve the starting torque.
This configuration is much like a shunt motor.
Step 4: USING THE PLANER
Here are some pictures of the plane taking a cut on a solid 4×4 segment.
This is a pointer to a planning operation you can watch and hear.
Note how the safety guard keeps the errant fingers away from the blade.
I have trimmed a solid core door in three passes to fit an older door jamb
on this machine.