[TCML] SRSG with John Freau Phase Control

[SusaX2 X2 <susax2@xxxxxxxxx>]

Hi Guys,

today I finished my new SRSG with John Freau's Phase Controller.
Here's a youtube video of the assembly in action
> http://www.youtube.com/watch?v=83ZdeQyoCqQ <

Since I don't have a scope I found an easy way to check if
the motor runs in sync and also the adjustable phase angle.

I took a strobe light used for checking ignition timing and
connected a small and simple mechanical relay (from tv or microwave PCB)
to where the signal clamp used to be.
The relay is connected via single rectifier diode to a small transformer
powered from mains.
This way the strobe flashes 50 times a second, mains frequency ofcourse.
(The tricky part was getting the camera's shutter time right..)

The motor is a 2HP 3000rpm 50Hz 220V single phase induction motor
with 2 flats milled on the rotor for salient pole operation.
The motor has it's original 30uF run capacitor and
it is internally wired semi star, since resistance between the 3 wires has
a 3:2:1 ratio
> http://nl.wikipedia.org/wiki/Bestand:Steinmetzschema-3.svg <

The phase controller has a 5A variac and a 18uF run capacitor
with a 1.5MOhm bleeder resistor. (And a 10A fuse ofcourse
to protect the variac in case the brown stuff hits the fan)

It has almost 90 degrees phase control over 70% of the variac's range
before loosing sync. I didn't measure any voltage rise at all,
voltage starts dropping as soon as the variac is turned.

I reckon almost 90 degrees is a maximum for a 3000rpm motor
and almost 45 degrees max. for a 1800 rpm motor.
This should make sense if you consider the 2 (or 4) field windings
and the position of the milled flats;
If you push the rotor to the point where the 2 flats meet up
with the point where the 2 field windings separate,
it's fighting 2 opposite magnetic fields.

Many kudos to John for inventing the phase controller.
I will though, accept all credits for the method
to check if the thing's working or not ;)

Mark
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla