[Prev][Next][Index][Thread]

High Voltage Test Equipment


----------
From:  terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
Sent:  Sunday, March 08, 1998 8:23 PM
To:  Tesla List
Subject:  Re: High Voltage Test Equipment

Hi Malcolm,
>
>----------
>From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
>
>Hi Terry,
>
>> From:  terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
>> 
>> 
><snip>
>
>>         My latest voltage divider is 1 inch long!  I thing you and I will
>> have the length extremes covered :-))  1/8th watt surface mount resistors
>> are typically rated for 400V max.  However, in oil, I would push that to
>> 4KV!  (I used to build the damn things).
>
>The voltage ratings associated with film resistors has to do with 
>internal arcing ruining the resistive material, not flashover 
>voltages or heating. I am currently getting in a rash of monitors for 
>repair with the same problems (all the same make surprise surprise!) 
>because as with so many designs, they have used a single 1/2 W 
>resistor to provide starting current for the SMPS from a 330V rail. I 
>am kept employed by people who use these techniques :)
>
>Malcolm
>

        A number of people have expressed concern over how hard I push the
voltage dividers in my system.  There are a number of points I should mention.
        1.      My fiber-optic probes provide total isolation between the
resistive divider and the rest of the world.  If a divider smokes, it will
not cause any harm.  No one will die and nothing expensive gets hurt.
        2.      The whole transducer / divider assembly costs about 12
dollars.  If it burns up, I really don't care.
        3.      As I work, the calibration on the probes gets checked every
few hours.  If a probe fails, I will know soon enough.  

        I designed these probes to be able to go into any situation and take
measurements where needed.  In order to do that, I needed small size, cheap,
and accurate.  Thus, I run the components very close to the limits they can
handle.  I don't care where the spec says they may become unreliable, I care
were they WILL blow up.  In some cases, they may be in for a one-way trip
but I feel the information is worth that small risk.  So far, they have
survived without any sign of failure.  I am a reliability engineer and I too
earn a living on electrical design errors $:-))  However, I have also
learned a few tricks along the way!
        
        Terry