>
> Even in wire circuits, electronic devices are faster and
> more reliable. That's why the move has been away from fuses.
> If resistors made good fuses, we would have a resistor panel
> in our houses and not a breaker box. We would use GFI
> resistors, and not GFI breakers, to protect people from
> equipment faults.
>
> 73 Tom
We don't see wide spread use of electronic devices in place of circuit
breakers in our home distribution panels even though they may be far
superior to circuit breakers.
We have to sometimes select the device that is the most economical and yet
provides an acceptable tolerance of protection.
As an example, circuit breakers used for AC mains interruption are very
unreliable compared to a fuse. A breaker can have trip errors as much as
600% or more over what they are speced at. Yet they are used extensively in
electrical circuits instead of the much more reliable fuse because of their
ease of use, convenience for resetting and the assurance that the proper
size device remains in the circuit and to not have to go find a new
replacement.
But if you have a critical circuit a fuse is a much better choice than a
breaker.
**(I have a friend that worked as an electrical power engineer and tested
many new breakers and found very wide tolerances in them)
The same can be said about amplifier protection circuits. The ideal
protection device is usually an electronic type protection circuit. But how
many hams will pay for those type devices?
In commercial use amplifiers it would of course be silly to have to remove
half the amplifier to replace a fuse when the amplifier needed to be quickly
returned to service. But a ham can tolerate the time.
It comes down to compromise. What is better, a circuit with no fuse at all
or a fuse that may not be the ideal device in the particular circuit.
As for grid circuit fuses, as long as the fuse does not cause further damage
to the tube it would seem a good thing to do. As evidence of no further
damage I understand there have been many amplifiers where the grid choke has
opened and not damaged the tubes. Now if there is more evidence that tubes
are damaged in this situation than not, then the fuse may not be such a good
idea.
73
Gary K4FMX
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|