Re: It Just Stopped

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

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Matt,
          A guess would be that the cap is breaking down in some
fashion with a high voltage applied. If you disconnect it, does the
NST arc over in the spark gap?

Malcolm

On 2 Aug 2004, at 18:10, Tesla list wrote:

 > Original poster: Mddeming-at-aol-dot-com
 >
 > Hi All,
 >      Something happened last night that has me puzzled. I was testing
 >      4.25"
 > coil. It had been run intermittently for about 1/2 hour. I fastened a
 > pointed rod to the center bolt of the topload (dual toroids) pointing
 > upward, preparatory to making a "pinwheel". I was getting nice 3ft+
 > arcs to the ceiling of the lab, (coil is caged 10' x 9' x 8'.) After
 > about a minute, it suddenly went dead. No arcs, no gap spark, no sound
 > except the vacuum on the sucker gap. It had been drawing ~18 Amps on
 > 30 Amp circuit prior to problem. Indicator lights showed power
 > reaching primaries of NSTs. Variac output showed 120V. No racing
 > sparks noted, no arcing to primary. I shut system down, waited ten
 > minutes, tried to restart... Nada!
 >      I disassembled everything and checked each component:
 >
 > Xfmr 1 Allanson 15/60:  6000v left and 5990v right to ground terminal
 > with 102V input. (My HV meter limit is 6 kV) Xfmr 2 Transco 15/60:
 > 5995v left and 5980v right to ground terminal with 101.8v input. Tank
 > cap: Maxwell 37xxx series, 30 nF nominal,. measured 29.95nF with RdShk
 > DMM and 30.91 on AADE L/C II-B. On the 14th of July, it measured
 > 31.07nF on the L/C II-B when air Temp was 11F warmer and Humidity was
 > 30% higher. Sucker Gap 1 HP vacuum spaced 7.5 mm. Safety Gap spaced 5
 > mm Left and 4 mm Right.
 >
 >      Reassembled everything and... Nada!!
 >
 > Any Guesses??
 >
 > Matt D.
 >
 >
 >