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Re: [Amps] Fuses

To: "Carl" <km1h@jeremy.mv.com>, "Roger \(K8RI\)" <sub1@rogerhalstead.com>, <amps@contesting.com>
Subject: Re: [Amps] Fuses
From: "James R Carr" <n7fcf@hctc.com>
Date: Sat, 8 Jan 2011 19:41:45 -0800
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Are 4-125A's used much anymore? I've accumulated several and a couple of 
sockets. Two appear to be brand new one a JAN, both Eimac and one that 
appears used.
Jim
N7FCF
----- 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 7:00 PM
Subject: Re: [Amps] Fuses


> 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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>>>>>>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>>>>>> _______________________________________________
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>>>>>>>>
>>>>>>>
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>>>>>>
>>>>>> _______________________________________________
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>>>>>
>>>>
>>>
>>
> 

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