[Amps] HV fuse

[R.Measures]

On Jul 15, 2004, at 3:08 PM, Ian White, G3SEK wrote:

> Oleg Skydan wrote:
>> Hi, All !
>>
>>> On the other hand, for tubes up to the 1500W class, Eimac's and 
>>> Rich's
>>> recommendation is a good one:
>>> >> limit I-peak with a suitable HV glitch R and use circuit 
>>> breakers, or
>>> >>250v fuses, in the primaries of the PS transformers.
>>
>> What do you think about switching HV off with the vacuum relay ?
>> Is it better than fuses/circuit breakers in the primaries of the PS
>> transformer ?
>
> It doesn't need to be as fast as a vacuum relay. With conventional 
> mains switching relays and an electronic anode current sensing 
> circuit, a crowbar short will usually shut down the HV without blowing 
> any fuses.

••  Ian --- The issue is seemingly to prevent  damage to the amplifying 
device from the current peak generated by the stored energy in the 
filter caps. Would a mechanical relay be fast enough to do this?  //   
What kind of a crowbar would be able to function in a 9000V power 
supply?
>
> The glitch resistor protects the tube against the first current surge 
> out of the HV capacitor, so there is no great strain on the relay.

••  If the glitch-R protects the tube,  we need a HV crowbar to protect 
______?
>
> You must always have mains fuses or breakers as well, but hopefully 
> these will only be a backup.
>
>
> -- 
> 73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
> http://www.ifwtech.co.uk/g3sek
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>
Richard L. Measures, AG6K, 805.386.3734.  www.somis.org