>
>At 04:25 PM 7/21/2001 -0700, 2 wrote:
>
>> >Why not the ceramic (cement) type Rich ? Reliability ? Shrapnel if an
>> >event occurs ?
>> >
>> >Tnx....Phil
>> >
>>/\ To be successful, a glitch resistor must not break down internally
>>during a major fault. If it does, a metal-vapour arc takes place -
>>which limits the V-drop across the resistor to c. 20v instead of the
>>needed several kV. Thus, the desired ability to limit current to a
>>finite value is lost. Shrapnel and internal breakdown are problems with
>>ceramic-type resistors. To find out if a glitch resistor is up to the
>>task at hand, (Note: the meters and their shunts should be protected
>>with suitable glitch-diodes). short the anode supply to ground with a
>>large plastic handle screwdriver. If there is a loud noise, the circuit
>>breaker opens, there is no sign of damage, and the ohms are unchanged,
>>the glitch resistor did its job.
>
>So, under fault conditions the ceramic ("cement") resistors are known to
>be prone to arcing/explosion/etc whereas the glass coated resistors are not
>? (or are less prone ?)
>
/\ ceramic power resistors have the element inside a thick ceramic
case. If the resistance element vapourizes, the case can fragment and
fly apart - much like a bomb casing.. With a glass coated / vitreous
enamel resistor, the element is on the outside. If the element
vapourizes, bits of the coating fly away but the body remains intact.
cheers, Phil
>
>
>>cheers, Phil.
>> >
>> >
>> >>- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
>> >>end
>> >>
>> >>
>> >>--
>> >>FAQ on WWW: http://www.contesting.com/FAQ/amps
>> >>Submissions: amps@contesting.com
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>> >>Problems: owner-amps@contesting.com
>> >
>> >
>> >
>>
>>
>>- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
>>end
>>
>>
>>--
>>FAQ on WWW: http://www.contesting.com/FAQ/amps
>>Submissions: amps@contesting.com
>>Administrative requests: amps-REQUEST@contesting.com
>>Problems: owner-amps@contesting.com
>
>
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>
>
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
--
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