Re: 2 questions: SRSG & LTR Caps

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 3/19/02 1:17:05 AM Eastern Standard Time, tesla-at-pupman-dot-com
writes:

Matt,

You may need to use about a 60uF cap or so.  The key is to 
measure the voltage across the motor, while rotating the variac
knob.  The voltage should rise about 3 to 5 volts over line voltage
at some point along the variac range.  Also, the motor should
remain locked for the full variac range or close to it.  Only
trial and error will determine the correct cap size.  

Cheers,
John


>
> Tried firing up a SRSG with phase control tonight with dismal results. I
> suspect the components are of incompatible size. No significant change in
> phase(<5deg), even using modified strobe (per Terry) to check visually.
>
> 1.     Salient pole motor 1/7 HP 3600 RPM 
> 2.     6"  2-electrode disk
> 3.     3.5A 120 V Variac
> 4.     15uf -at-660V Cap
> 5.     47K-ohm resister across cap
> 6.     5A fuse
> While I have lots of caps and resistors, but don't have a feel for direction
> or
> order of magnitude of change needed. Anyone with experience please advise.
>
> For LTR Caps with 15 kV NSTs is the rule of thumb of 0.5nF per mA fairly
> linear
> for 30-300 mA? i.e. 15nF -at-30 mA, 30 nF -at- 60 mA, etc.
>
> Thanks, 
> Matt D.