For years I have used panel mounted breakers like the Airpax, ETA,
Potter Brumfield W91X series, Seimens, etc. I think a number of
manufacturers have consolidated a bit, but most make similar packages
that can be uses as a second source for each other. The instantaneous
MH is fine, it really isn't instantaneous but closer than a thermal
breaker I would guess. Just rate it to be above the RMS current you
plan on drawing (also the inrush if you don't have step start should
be considered, and either the delay curve for the breaker chosen for
this, or a slightly larger breaker chosen. Breakers are rated for
line to ground voltage, for a 2 pole breaker. It is very difficult to
find a 480 VAC panel mounted breaker, for instance. However one
realizes that 277 volts is all that is present with respect to ground.
High speed electronic crowbar or overcurrent sensing can be used to
open the primary power and the breaker protects your wiring and iron
from burning up in a direct short. Some breakers can be obtained with
separate trip coils which can be triggered from an overcurrent
circuit to remove AC power that way. Only thing is that you might
drop cooling, filaments and all this way and perhaps you want to keep
a little cooling going until your tube cools down (depends on if
bottle or with handles, etc.).
These breakers are sold at Allied and Newark among other
distributors. Good choices...
73
John
K5PRO
To: <amps@contesting.com>
>Date: Sun, 7 Oct 2001 12:52:48 EDT
>From: ToddRoberts2001@aol.com
>Subject: [AMPS] CIRCUIT BREAKER FOR TRANSFORMER PRIMARY CIRCUIT
>
>Can anyone recommend a suitable panel-mount 2-pole circuit breaker for the
>240V primary circuit of a high-voltage transformer power supply? There are so
>many different types of circuit breakers available : Magnetic -Hydraulic,
>Thermal - Magnetic, medium-delay etc. the choice can be confusing. I would
>assume an instantaneous acting Magnetic-Hydraulic would be the best but even
>those seem to have different time-delay settings in catalogs I have looked
>at. Grainger seems to have a good selection but the catalog listings are
>confusing. I would guess a 20-25 amp rating would be good for a last line of
>defense and compatible with the ratings of my house wiring. Thanks for any
>suggestions. 73 Todd Roberts WD4NGG .
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