Re: (ET) Aaargghh!!!!

["David Roden" <etpost drmm net>]

On 26 May 2017 at 11:13, bushman165s--- via Elec-trak wrote:

> when you finally closed the disconnect, a surge of current caused the
> diode/s to short. 

I don't see what you're getting at here.  The tractor was off.  Why would 
a 
current surge result from closing the disconnect?  What am I missing?

The diode(s) probably shorted when Michael applied power to the charger.  
Shorted diodes would be a short circuit right across the full transformer 
secondary, making for a BIG load. That's what caused the odd sound and the 
breaker trip.

> I have been using solid state rectifiers to replace the diodes for a
> while now. 

I don't quite understand this.  Granted, I'm an old guy, but in the 
nomenclature I learned in the 1960s and 1970s, that's what silicon diodes 
like the original 1N3493 are -- solid state (semiconductor) rectifiers.

Maybe I'm just not familiar with these modules.  Can you provide a 
weblink? 
Thanks.

> The rectifiers are 10x quieter, also.

Don't see how; nothing in a rectifier makes noise.  

As I said, I've never used the ET charger, but I would expect that any 
noise 
would come from the transformer.  It's good old 60 Hz hum.  

Louder hum (more like a buzz, really) is characteristic of a classic 
battery 
charger ferroresonant design, which the GE uses.  

That's what the cap is for.  Briefly, with the extra transformer winding, 
it 
introduces magnetic saturation in the core to stabilize the output 
voltage. 

Here's a much better and more complete explanation than mine above: 

http://www.electroncoil.com/ferroresonant_transformers.php

If the transformer is making less noise, I'd worry that it may not be 
doing 
what it's supposed to do.




David Roden - Akron, Ohio, USA

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