A 1hp FASCO motor was purchased for use in the Synchronous Rotary Spark Gap, This has been modified to run at the synchronous speed of 3000rpm, The modifications are shown in the photos in this section. The rotor disc has now been completed, The G10 disc can be used with either 4 or 8 rotating brass electrodes which allows for a break rate of either 200 or 400 breaks per second. Using a remote phase adjuster i can get up too +/- 45 deg phase shift.
Rotor Before Modification
The modification process involves grinding flats onto the rotor to force the motor to run in salient pole mode. This process need to be done carefully to ensure that the correct amount is ground off each flat, this also helps ensure the rotor will remain balanced. For motors just under 3000rpm, two flats need to be ground onto the motor, these are 180deg apart, for 1500rpm motors there will need to be four flats, all separated by 90deg.
Rotor After Synchronous Modification.
Showing How Tungsten Electrodes are mounted using Set Screws
Motor Mounted in Frame
SRSG Mounted In Frame, Showing Polycarbonate Shield and Perspex frame used to mount all the MMC Capacitors. In this picture you can see the 50A red cable that was initially used. After short runs significant heating in this cable was noticed. This has now been replaced with 40mm^2 cable rated at about 200A.
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Variac Used In Remote Phase Shifter. Rated at 16A, 240V. Encased in wooden box.
The following photo shows how the PFC correction caps, are mounted to the 1HP motor, these caps are used in the Phase Shift Circuit. There is also an IEC Socket / Filter Module. Several MOV's have also been mounted inside the blue box at the top of to motor, to help protect it against high voltage spikes.
