[AMPS] AL-1500, AL-82, AL-1200, QRO???

[2@vc.net (measures)]

>
>Andy Cook, G4PIQ wrote:
>>
>>Rich wrote
>>> The glitch R needs to be in the positive HV lead.
>>
>>Piece of education needed for me here. The glitch resistor is there to 
>>limit fault current in event of a flash-over. The only source of these big 
>>currents is from the filter capacitor and the only route for the current 
>>back to that cap is via the 25R resistor. So why does the resistor need to 
>>be in the +ve line.
>>
>You're right, it doesn't necessarily. 
>
>There are just two things to take care of, if the glitch resistor is in
>the negative lead: 
>
>1. To be sure that the resistor is the *only* path back to the HV-minus
>point (and is not bypassed by the meter protection diodes). This
>requires some thought and drawing-out the simplified DC circuit to make
>sure it's correct.
>
>2. To be sure that the insulation around the negative end of the
>capacitor stack will withstand voltages spiking to MINUS HV. This also
>applies to the negative end of the glitch resistor and any connecting
>wiring.
>
in other words, can the fil. transformer CT handle a several kV spike 
during a hv arc.?  Putting the glitch R in the pos. lead eliminates this 
problem.  On a Henry 3KA, 2K4,et cetera, the 7.5-ohm glitch resistor in 
the neg. circuitry is virtually certain to burn out  during a glitch.  
>
end


-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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