Lynn,
You might want to take a look at the circuit breaker to determine that it is
functioning properly.
I would try monitoring the primary current, such that you could measure and
hold the peak value after a trip. Circuit breakers are designed with various
time / overcurrent properties to meet different needs. Circuit breakers
found in a residential service panel often have two types of protection:
instantaneous and time delay.
Time delay protection begins it's timing cycle at 1x the breaker rating. At
this level the breaker would take a very long time to trip, if it tripped at
all. At 3x the breaker rating, I usually expect a trip in ~ 40 - 60 seconds.
Instantaneous protection covers low Z faults. This function is often set to
pick-up at ~ 10x the breaker rating, with no intentional time delay when
that current level is reached. I've seen some molded case breakers that had
instantaneous function only. On this type of breaker, one must keep in mind
that tripping will occur as soon as the set point is reached.
Molded case circuit breakers are a rather simple and crude device. I've
tested a lot of them and identified a good number of bad ones. This is why I
recommend a "peak lock" clamp-on ammeter on the primary to compare
"non-trip" operating current peaks, with those peaks that trip the breaker.
You also mentioned noise. A bad breaker might make an audible buzz prior to
a nuisance trip.
In summary, you might have a bad breaker or a breaker that is not matched to
your needs.
You can test the breaker with a high current, current limited source. An AC
welder and an ammeter will give you a good indication of the breaker
tripping characteristics. I would first test the "long time" trip by quickly
running the current level up to 300% of the trip rating and hold it there.
If it tripped in ~ 30 to 60 seconds I would be happy. If it tripped
instantaneously, it might just be that it is an instantaneous only breaker.
To find the instantaneous trip point, pulse the current on and off as you
raise the value until the breaker trips. The peak hold ammeter function is
really needed for this test. Also remember that the reason for pulsing the
current (as opposed to ramping it up) is because the trip coil on an
instantaneous only breaker will overheat at steady state current levels well
below the trip point.
Hope this is helpful in some way,
73,
Jeff - K1LE - CT ><>
----- Original Message -----
From: "Lynn" <no9z@soltec.net>
To: <amps@contesting.com>
Sent: Thursday, April 10, 2003 9:51 PM
Subject: [Amps] Re: PS project part2
> Thanks for all the input on the ps problem so far. For a little more
> background info, the amp I am using works fine with a smaller ps
> (4kv 1 amp). I built the new ps inorder to obtain higer plate voltage
> and less grid current.
>
> The amp is ok and the radio is ok. I am not going to use 2 amps
> at 5kv. I am just looking for maximum of 3kw out (It should do that
> anyway) and better efficiency. This powersupply will provide
> plenty of juice. I have seen 1 amp continuous with no problem.
>
> I will restate again that I am using a transformer that was designed
> for a choke input, but I am not using one. The email below is
addressing
> what I believe to be the root of the problem. When I key the amp,it has
> about 400 ma of idleing current (no drive). If I send a cw dit or dah,
> sometimes but not always the breaker will trip. Sometimes you hear that
> thud like when turning on a larger 12 volt power supply and the switch is
> flipped at the peak of the ac cycle. And worst case the breaker flips on
> just a couple quick dits. WIth the smaller power supply I can drive
the
> amp to 1.2 kw. With the bigger power supply the breaker will trip when
> the thud occurrs. I have not exceeded 800 watts yet with the new ps.
>
> So I am still looking for a solution of sorts. Please read Bill's
> comments
> below. I am using stepstart which requires about 10 seconds (timer).
>
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