[Milsurplus] Inverter idea

[Dick]

Interesting, Pete:

The instructions that came with my UPS from APC said not to plug a spike 
filter into the output.  What I have done, though, is put an isolation 
transformer between the UPS output and the load.

Dick


----- Original Message ----- 
From: "Peter Gottlieb" <nerd at verizon.net>
To: "Dick" <rertman at ix.netcom.com>
Sent: 11 May, 2005 10:34
Subject: Re: [Milsurplus] Inverter idea


> When I designed inverters at APC all our outputs (SmartUPS series) were 
> filtered and looked like decent sine waves and there was no problem 
> feeding them into any kind of spike filter.  Even the stepped-sine BackUPS 
> series were free of spikes and could be fed into spike filters.
>
> Most spike filters use MOVs, which although they have some capacitance, 
> really react primarily to voltage.
>
> Peter
>
> ----- Original Message ----- 
> From: "Dick" <rertman at ix.netcom.com>
> To: "MILSURPLUS" <milsurplus at mailman.qth.net>; <cosmoline at ba-watch.org>
> Sent: Wednesday, May 11, 2005 1:18 PM
> Subject: Re: [Milsurplus] Inverter idea
>
>
>> Marty and gang:
>>
>> A word of caution.  Don't feed the output of a synthesizer type inverter 
>> into a spike filter.  The filter sees the rise and fall times of the 
>> synth'ed waveform as a spike and clamps it so that the filter appears as 
>> a short to the inverter output.  You get the same warning with a UPS 
>> backup.
>>
>> Happy inverting,
>>
>> Dick
>>
>> ----- Original Message ----- 
>> From: "Marty Reynolds" <cosmoline at ba-watch.org>
>> To: "Jack Antonio" <scr287 at sbcglobal.net>
>> Cc: <milsurplus at mailman.qth.net>
>> Sent: 11 May, 2005 10:07
>> Subject: Re: [Milsurplus] Inverter idea
>>
>>
>>> .
>>>>
>>>> Has anyone tried to see if these inverters can be
>>>> altered to make 400 cycles instead of 60?
>>>>
>>>> Jack
>>>
>>> OK, I just looked into a 175W GE.  3 16-pin dip ICs, one
>>> 20 pin.  Lotsa glue pieces.
>>>
>>> This was 2nd visit, 1st being a year back.  Again I felt
>>> like the nude in the sculpture looking @ the skull saying
>>> "Alas poor Yorrick."
>>>
>>> These modern inverters are some kinda neat.  They're PWM
>>> to deliver 115VAC rms independent of load.  Waveform is
>>> series of steps that approximate a sine.  Each step made
>>> of lots little PWM interior spikes.  And they're always
>>> delivering ~300V p-p.
>>>
>>> If you find the answer Jack, call - don't write!
>>>
>>> Makes you wonder how they come to market so cheap
>>>
>>> Time flies like an arrow
>>>
>>> Fruit flies like a bananna
>>>
>>>   Groucho
>>
>>
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>
>