[NSRCA-discussion] Power Supplies

[Duane Beck]

Metal-oxide varistor?
http://en.wikipedia.org/wiki/Varistor

Ronald Van Putte <vanputter at gmail.com> wrote:

>MOV?  Hmmm.  Let's see:  Mother Of V???,  Miniature Oval V???  
>
>I know what joules are, but maybe many don't know that they have nothing to do with the family jewels.
>
>Ron
>
>On Jul 2, 2013, at 10:58 PM, Richard Lewis wrote:
>
>> Items that go bang are likely MOV's. they look like big lollipops. They fail like firecrackers.  They are usually in surge/spike protection circuits. Rated in Joules of energy they can absorb they fail when they exceed their total Joule rating.  The higher the voltage they see the faster they rack up the Joules and "POW"...when they fail, they  fail as a short and usually take out another current sensitive element (fuse).
>> 
>> Or, they are really caps and I am full of it...:)
>> 
>> Richard
>> Sent from my mobile device.
>> 
>> On Jul 2, 2013, at 9:36 PM, Ronald Van Putte <vanputter at gmail.com> wrote:
>> 
>>> I have no personal experience with this type of failure, so I really have no comment other than to say that maybe an investment in a couple of the subject ceramic caps might be warranted.
>>> 
>>> Ron
>>> 
>>> On Jul 2, 2013, at 9:25 PM, Astropattern wrote:
>>> 
>>>> Ron, 
>>>> Good article and info. One of the issues I would ask about and that I've heard has happened to others is how robust these power supplies are. I have purchased three of these in the last 18 months and all of them failed with a dramatic loud "gunshot" sound after a few months of use. Usually, they blow within a minute of plugging them in. Careful inspection of the internals reveals a vaporized ceramic cap (always the same one).
>>>> 
>>>> Would be great for someone who knows these well ( both the HP and the Dell versions) and can comment on how these should be operated. I imagine they are designed to be turned on once and left running for years...so plugging them in 4 times during a single weekend probably doesn't sit well. 
>>>> 
>>>> Just curious. $20 a piece is hard to beat. 
>>>> 
>>>> Thanks, 
>>>> 
>>>> John
>>>> 
>>>> Sent from my iPad
>>>> 
>>>> On Jul 1, 2013, at 10:50 PM, Ronald Van Putte <vanputter at gmail.com> wrote:
>>>> 
>>>>> A lot of electric-power pilots are building or buying charge boxes.  Many of the charge boxes contain the HP DL380 G4 DPS-600PB 12V/575W power supply.  
>>>>> 
>>>>> Since they are so inexpensive to acquire and so simple to convert for our use, I'd like to provide some information about them.
>>>>> 
>>>>> These are so called "hot swap" power supplies.  They are really tough and were designed to be used in a computer server 24/7.  Their output is 47 amperes at about 12.5 volts.  You can use two in series to provide 47 amperes at about 25 volts.
>>>>> 
>>>>> You can buy them at places like eBay for about $15 delivered if you shop around, particularly if you look for lots of two or three.  These power supplies cost upwards of $300 when they were in active use, but the servers they were designed to work with have been retired, leaving a lot of these server power supplies as surplus.  Consequently, you can get them pretty cheap. 
>>>>> 
>>>>> I usually show pilots with any measure of soldering skills how to convert them for our use.  The conversion takes about 30 minutes.  The rest, who can't solder or can't follow simple directions, I do the conversion for them.
>>>>> 
>>>>> There is a great description how to do the conversion of the HP model DPS-600PB power supply here:  https://sites.google.com/site/tjinguytech/my-projects/HP47A
>>>>> 
>>>>> Any questions?  E-Mail me offline.
>>>>> 
>>>>> See you at the Nats.
>>>>> 
>>>>> Ron Van Putte
>>>>> _______________________________________________
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