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Hi Alex, Thanks for the update and for the additional information about your thyristor ballast/controller. Because of the additional voltage stress when using the 8 MOT stack, you may wish to look at using a larger diameter of the toroid on L2 (is it providing sufficient shielding of the winding). Are you seeing any signs of breakout at the top of C2? If so, you may need to also look at increasing the Radius of Curvature (ROC) of C2. Physically lowering the C2 toroid may help a bit by providing improved shielding at the top of L2. Converting from Mylar to a lower dielectric constant material (such as sheet LDPE) may help reduce the E-field stresses in any air gaps within the dielectric circuit between L1 and L2. Corona in these air gaps may result in "corona charging" of the Mylar surface, stimulating low energy gliding/racing sparks. Also, do the racing sparks seem to be consistenty originating from certain spots on L2? If so, are there any obvious defects in the winding, coating, etc. at these points that need to be fixed/repaired? Good luck and please keep us posted on your results and please provide any links to pictures showing your progress. Best regards, Bert
: Hi Bert,
: I´ve made a second test of the big magnifier.
: The magnifier is now driven by a 8Mot stack (16kV)and
: an ASRG (2950min-1 0,315"copper-tungsten Elektrodes at 11,4"
: diam.)
: I´ve testet a new method of ballasting: I used a phase controller with
: current regulator to adjust current.
: The phase is cuted by an device called powerblock which consists of
: two powerthyristors in one block for antiparallel use.
: I can use the controller without the regulator instead of a variac.
: With regulator i can regulate the current to the desired level.
: This works,and weight much less! than a power variac and a ind.ballast.
: With the big powerblocks you can handle around 300A and the
: max rev.Voltage up to 1600V.
: (with cooling radiator and fan aound 60lbs.for 300A)
: The use of an RC-safetynetwork prevents the
: thyristors from overvoltage.I use the 65A thyristors.
: The real current (for the reulator)was measured with a current
: transformer.
: The only problem,i have to make the regulator a little faster.
: I´ve a link to this devices to our company and I use the older version
: (AEG / powerblocks from eupec)of the ISR02.
: Now my problems: With the 8Mot Stack I have 6kV more voltage as with the
: Radartransformers in the first test.Now i´ve racing sparks again.
: The isolation of each of the three PET plastics could withstand the 16kV
: AC.
: i think my main problem is the height of the toroid C2 or the last
: spaced turns.
: I tell you more,if the next tests resulted in disaster or performence.
: alex
:
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