Re: Phase adjust

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Ed,

My 1/4 HP motor needs like 100uF so I would guess that you need a lot more
capacitance.  

Each 10uF of capacitance will draw about 1/2 amp at 120VAC.  So for a 10uF
cap you would need a 5 amp fuse (maybe a bit more).  In your case, the fuse
was right so the thing was probably saturating.

Perhaps someone has a 1/3 HP motor like yours who has the value which seems
to be pretty critical.  John also had a list of motors and caps to go with
them (I think).  If not we should start one.

Cheers,

	Terry


At 04:02 PM 12/24/2000 -0500, you wrote:
>John & Terry,
>
>I finally got John Freau's sync rotary phase adjuster circuit set up today.  
>I have a 1/3 H.P. motor modified to run synchronous at 3600 rpm.  This motor 
>needs 100 volts minimum to stay locked.  I used a variac that will produce 0 
>to 145 volts ac and set it at 125 volts to power the circuit.  I used two 27 
>ufd caps in parallel for a total of 54 ufd and mounted them right near the 
>sync motor, in parallel.  These are motor run caps rated at 370 v ac.  The 
>phase adjuster variac is a 10 amp powerstat which yields 0 to 250 mh in 
>adjustment.  As I start to increase this variac, the motor voltage falls 
>quickly and within maybe 20 % of increase, falls below 100 volts and it blows 
>the fuse, which is a 3 amp fast blow type.  I tried it again, same result.  
>Do I need much larger caps with a 1/3 H.P. motor?
>
>Ed Sonderman
>