Never mind the blessings, just send money or your first born.
----- Original Message -----
From: "James R Carr" <n7fcf@hctc.com>
To: "Carl" <km1h@jeremy.mv.com>; "Roger (K8RI)" <sub1@rogerhalstead.com>;
<amps@contesting.com>
Sent: Saturday, January 08, 2011 9:32 PM
Subject: Re: [Amps] Fuses
> Oh bless you your worthiness
> ----- Original Message -----
> From: "Carl" <km1h@jeremy.mv.com>
> To: "James R Carr" <n7fcf@hctc.com>; "Roger (K8RI)"
> <sub1@rogerhalstead.com>; <amps@contesting.com>
> Sent: Saturday, January 08, 2011 5:46 PM
> Subject: Re: [Amps] Fuses
>
>
>>I like it when the commoners react fast.
>>
>> You may carry on.
>>
>>
>> ----- Original Message -----
>> From: "James R Carr" <n7fcf@hctc.com>
>> To: "Carl" <km1h@jeremy.mv.com>; "Roger (K8RI)" <sub1@rogerhalstead.com>;
>> <amps@contesting.com>
>> Sent: Saturday, January 08, 2011 8:09 PM
>> Subject: Re: [Amps] Fuses
>>
>>
>>> Excuse us your royal highness
>>> ----- Original Message -----
>>> From: "Carl" <km1h@jeremy.mv.com>
>>> To: "James R Carr" <n7fcf@hctc.com>; "Roger (K8RI)"
>>> <sub1@rogerhalstead.com>; <amps@contesting.com>
>>> Sent: Saturday, January 08, 2011 4:36 PM
>>> Subject: Re: [Amps] Fuses
>>>
>>>
>>>> Can you two get back to earth and keep it somewhat relative to ham amps
>>>> in the under 20KW range (-;
>>>>
>>>> Carl
>>>> KM1H
>>>>
>>>>
>>>> ----- Original Message -----
>>>> From: "James R Carr" <n7fcf@hctc.com>
>>>> To: "Roger (K8RI)" <sub1@rogerhalstead.com>; <amps@contesting.com>
>>>> Sent: Saturday, January 08, 2011 7:21 PM
>>>> Subject: Re: [Amps] Fuses
>>>>
>>>>
>>>>> Down in prosser, WA about 30 years ago they had a problem with a
>>>>> pottato
>>>>> processing plant and a mechanic came running into the panel room and
>>>>> before
>>>>> anyone could stop him threw the main 480v 3 phase breaker. The plant
>>>>> was
>>>>> under full load with motors up the cazoo. When the back emf hit it
>>>>> blew the
>>>>> breaker out of the panel. The guy was lucky he wasn't hurt.
>>>>> I retired in 2000 and there is a whole raft of devices that have come
>>>>> on
>>>>> line since.
>>>>> Jim
>>>>> N7FCF
>>>>> ----- Original Message -----
>>>>> From: "Roger (K8RI)" <sub1@rogerhalstead.com>
>>>>> To: <amps@contesting.com>
>>>>> Sent: Saturday, January 08, 2011 2:38 PM
>>>>> Subject: Re: [Amps] Fuses
>>>>>
>>>>>
>>>>>>
>>>>>>
>>>>>> On 1/8/2011 5:22 PM, James R Carr wrote:
>>>>>>> Agreed, The first instant in time you have the full output of
>>>>>>> Bonnyville
>>>>>>> Dam
>>>>>>> on the fault. But then the impedance of the system kicks in and
>>>>>>> limits
>>>>>>> it.
>>>>>>> But still depending on the size of the utility transformer, it's
>>>>>>> eficiency,
>>>>>>> the length and size of the service conductors, you can still have
>>>>>>> several
>>>>>>> thousand amps at the main panel and down the line. About 20 25 years
>>>>>>> ago
>>>>>>> they had to increase the fault clearing ability all the breakers in
>>>>>>> the
>>>>>>> panels from 5000 amps to 20000 amps due to the increased use of low
>>>>>>> loss
>>>>>> Our mains weren't quite that large, but they were big...It's been too
>>>>>> long for me to remember the actual size.
>>>>>> They used magnetic quenching in arc chutes. They could open under
>>>>>> full
>>>>>> load without self destruction, BUT with big transformers down stream
>>>>>> (Inductive loads) the "kick back" was so bad that reverse EMF would
>>>>>> take
>>>>>> out almost any thing attached to the line. So, if you blew one of the
>>>>>> mains you knew it was going to be an expensive day.
>>>>>>
>>>>>> 73
>>>>>>
>>>>>> Roger (K8RI)
>>>>>>> transformers by the utilities. basically the breaker can clear it
>>>>>>> without
>>>>>>> exploding. It probably will be terminally damaged though. I have
>>>>>>> seen
>>>>>>> buss
>>>>>>> bars twisted into pretsels by a dead short and a breaker that didn't
>>>>>>> clear
>>>>>>> quick enough.
>>>>>>> Jim
>>>>>>> N7FCF
>>>>>>> ----- Original Message -----
>>>>>>> From: "Jim Thomson"<jim.thom@telus.net>
>>>>>>> To:<amps@contesting.com>
>>>>>>> Sent: Saturday, January 08, 2011 2:18 AM
>>>>>>> Subject: [Amps] Fuses
>>>>>>>
>>>>>>>
>>>>>>>> Date: Sat, 8 Jan 2011 08:34:30 +0000
>>>>>>>> From: Ian White GM3SEK<gm3sek@ifwtech.co.uk>
>>>>>>>> Subject: Re: [Amps] Fuses
>>>>>>>>
>>>>>>>> James R Carr wrote:
>>>>>>>>> Where pray tell do you get a hydraulic breaker? I have installed
>>>>>>>>> several thousand over the years but have yet to see one filled
>>>>>>>>> with
>>>>>>>>> oil. As for current limiting devices, the fastest breaker will
>>>>>>>>> hold in
>>>>>>>>> for three to seven full cycles. To be current limiting, a fuse has
>>>>>>>>> to
>>>>>>>>> clear in less
>>>>>>>>> than 1/2 cycle.
>>>>>>>> A fuse provides NO current limiting until it blows; and a breaker
>>>>>>>> provides NO current limiting until it breaks.
>>>>>>>>
>>>>>>>> A lot of damage can be done in those first few milliseconds, which
>>>>>>>> is
>>>>>>>> why the fuse/breaker is only PART of the solution.
>>>>>>>>
>>>>>>>> We always need a surge limiting resistor in the B+ as well, to
>>>>>>>> provide
>>>>>>>> instantaneous current limiting until the fuse/breaker takes over
>>>>>>>> and
>>>>>>>> finally breaks the circuit.
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>>
>>>>>>>> 73 from Ian GM3SEK
>>>>>>>> http://www.ifwtech.co.uk/g3sek
>>>>>>>>
>>>>>>>> ## Agreed. The purpose of the mag-hydraulic breaker is [A] handy
>>>>>>>> dandy
>>>>>>>> way of opening off the 240 v line, without having to kill the
>>>>>>>> dedicated
>>>>>>>> breaker in the
>>>>>>>> main 200A panel. [B] eliminate any follow on current.
>>>>>>>>
>>>>>>>> ## On my latest 7700 vdc supply, I use a Buss HVU series, sand
>>>>>>>> filled
>>>>>>>> HV fuse..rated at 3A..in series
>>>>>>>> with the B+ lead. The HV fuse gets inserted just prior to the kw
>>>>>>>> rated
>>>>>>>> glitch R, which consists of 4 x
>>>>>>>> parallel globar type AS energy absorbing type resistor's, 1.5"
>>>>>>>> diam x
>>>>>>>> 18' long. [ 4 x 200 ohm in parallel= 50 ohms]
>>>>>>>> 7700/50 ohms = 154A. max fault current. Now 154 A of fault
>>>>>>>> current,
>>>>>>>> flowing through a 3 A rated
>>>>>>>> fuse, will open VERY fast. [ the fuse is running at 5100% of it's
>>>>>>>> rating]. I use a 50 ohm glitch R on the
>>>>>>>> smaller supplies as well... with the provisio that a smaller rated
>>>>>>>> HV
>>>>>>>> fuse
>>>>>>>> is used..like 1A, etc.
>>>>>>>>
>>>>>>>> ## I also use a 2nd Buss HV fuse, in the sec of the plate xfmr,
>>>>>>>> [one
>>>>>>>> leg
>>>>>>>> only], between sec and input to
>>>>>>>> FWB. In normal operation, with any B+ to chassis fault, the B+ HV
>>>>>>>> fuse
>>>>>>>> alway's blows open 1st..so the
>>>>>>>> breaker used in the 240 v line is sorta a moot point. That B+
>>>>>>>> fuse
>>>>>>>> concept has been tested 34 x times
>>>>>>>> now, and nothing ever happens..except a blown HV fuse. Once, some
>>>>>>>> of
>>>>>>>> the
>>>>>>>> blown HV fuses were
>>>>>>>> 'refurbished' with a single strand, soldered on the outside..and
>>>>>>>> wrapped
>>>>>>>> with 88 tape. In one case, the
>>>>>>>> wire ga of the single strand refurbished job was too big.. and the
>>>>>>>> end
>>>>>>>> result was the parallel pair of 100
>>>>>>>> ohm, 225 W- WW's were literally incinerated, burnt to a crisp.
>>>>>>>> That
>>>>>>>> was
>>>>>>>> with a 165 uf filter cap..and a 253 lb
>>>>>>>> dahl hypersil xfmr. That particular glitch R was replaced with 4
>>>>>>>> parallel 200 ohm, 225 W, wirewounds
>>>>>>>> [ $12.00 each, from mouser],and the correct size HV fuse. Zero
>>>>>>>> problems
>>>>>>>> since then, and you can literally
>>>>>>>> cro-bar it all day long. I would not trust any of these glitch
>>>>>>>> R's,
>>>>>>>> even
>>>>>>>> big ones..without a prior series HV fuse,
>>>>>>>> not with big uf caps, huge amount's of joules involved, and then
>>>>>>>> trying
>>>>>>>> to
>>>>>>>> rely on a breaker [ or even the
>>>>>>>> 2nd HV AC fuse].
>>>>>>>>
>>>>>>>> ## In one instance, one of the hv lytics [ 3900 uf @ 450 vdc]
>>>>>>>> towards
>>>>>>>> the hot end of the string, arced through a
>>>>>>>> crack in the plywood, and launched itself. Since the fault was
>>>>>>>> before
>>>>>>>> the B+ fuse.... the 2nd HV fuse blew.
>>>>>>>> [ the one located between sec of xfmr and FWB]. The 96 x 6A10's
>>>>>>>> in
>>>>>>>> the
>>>>>>>> FWB were not damaged. In 2 x instances the
>>>>>>>> 240 vac breaker popped open. Once when a screw removed from a 6"
>>>>>>>> fan..and
>>>>>>>> the AL fan swung down like a pendulum
>>>>>>>> and hit one side of the 240 vac buss. [ and blew a chunk out of the
>>>>>>>> fan
>>>>>>>> casing]. The 2nd time was a B+ fault.
>>>>>>>>
>>>>>>>> ## I use a simple 50 ohm-50W WW on my L4B's..with the stock
>>>>>>>> drake HV
>>>>>>>> B+ fuse. [ consist of a .82 ohm, 1 watt carbon R ].
>>>>>>>> The stock .82 Ohm R always blows cleanly in 1/2. I have only
>>>>>>>> had 2
>>>>>>>> x
>>>>>>>> ever blow open since 1977.
>>>>>>>>
>>>>>>>> later... Jim VE7RF
>>>>>>>> _______________________________________________
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>>>>>>
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>>>>>
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>>>>
>>>
>>
>
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