Wednesday, April 12, 2006

Invesigating the main charging system

We put the good Eratron SCR controller connected to H.V. transformer, then we set the charing voltage 10 kV to measure the charing voltage and transformer secondary current. It was shown in the right picture, these wave forms are similar to the scope traces recorded on 9 March, 2006. Note the second step in the firing angle indicating that the charging cycle has been disrupted by the Thyratron firing too soon. It was hypothesized that the extra current drawn before and during the Thyratron firing caused the 10K resistors of the charing string to overheat.

Assuming the repitation rate is 0.4 Hz, the Stanford Box will send a trigger pulse per 2.5 second. According the old timing setup, the firing angle should be sent after 2.1531 seconds. From the left timing diagram, the Thyratron was triggered during the capacitors were charging. The time delay between firign angle and thyratron firing was around 347 ms, which matched the scope traces. The timing must be adjusted to move the charging time backward or forward such that the charging cycle started after or before the thyratron firing.

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