Attachments to CAT Chat Minutes - March 15, 2004
Oxford Cryo-pump Restart Simulator
Simulator was built to determine how oxford ckt was configured and why there were times when the restart package failed. Additional indicator lights(timing HI , RL2 active & Restart) were added to show conditions.
As shown in black is how Oxford package is wired - if timers are properly configured - it works, however, with timing input of T2 tied to 24VDC, at times the timing circuit never saw the power outage (simulated by opening and closing SW1) since the 24 VDC supply decayed "slowly" and although main flickered, T2 never saw it. Removing the "timing" connection to pin 3 of T2 (shown with red slashes) and connecting "timing" connection (pin 2 of T2) directly to 120VAC insures that T2 is triggered if there is a line fault and does not depend on the 24VDC decay.
There is NO direct line tie to 120 VAC in the chassis that contains the restart ckt. To accomplish suggested circuitry in red, one would have to run the direct 120VAC using proper connections