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Generators & Electric Motors General Discussion Antique Generators and Old Electric Motors: Questions and answers about restoring and showing old power generation systems.

Generators & Electric Motors General Discussion

Unable to Field Flash


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  #11  
Old 12-23-2018, 11:23:06 AM
Cavalry Cavalry is offline
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Default Re: Unable to Field Flash

I was able to once again resuscitate the pile. It would not take a flash with the standard 12v method, the hand turning AC drill method was equally ineffective, but 10 seconds spinning the drill with another drill did the trick. Thanks to all that helped get it going again.
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  #12  
Old 12-23-2018, 01:10:48 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: Unable to Field Flash

Quote:
Originally Posted by Cavalry View Post
...THe AVR appeared to be working during the same disconnected field test the field outputs had current.
It's not at all clear what you meant to say here - at least to me...


Quote:
As soon as I reconnect the field to the AVR I am back to 5VAC output at the generator.
That should be enough for a SX460 to self-flash. (at least according to the SX460 specs.)

Quote:
The stamford manual suggests field flashing while running and the AVR connected via 12VDC to field with a blocking diode. I tried this and instantly smoked the AVR.
Well, that's weird. I'd double check and be sure you have things connected as the SX460 manual describes. I can't imagine why this test, properly conducted, would smoke an SX460. Unless, of course your field is under 15 ohms, you had the diode installed wrong, connected the 12V to the wrong place, or your field needs more than the SX460's 4 amp rating.

What is your field resistance? And how much current does the field need?

For what it's worth, I've used SX460's on several brushless sets, and never needed to flash them, not even once. I have a hunch that the field polarity matters, and it's not obvious that reversing it will do any damage on the brushless sets I'm familiar with. So, if you understand the risks, it might be worth swapping the F+ and F- drive to your static field coil.
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Old 12-25-2018, 01:18:42 AM
Cavalry Cavalry is offline
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Default Re: Unable to Field Flash

Quote:
Originally Posted by Jim McIntyre View Post
It's not at all clear what you meant to say here - at least to me...

What I was attempting to say was during the test where I applied unregulated 12vdc to the field for testing, I also checked the output of the AVR to make sure it was working.


Quote:
Originally Posted by Jim McIntyre View Post
Well, that's weird. I'd double check and be sure you have things connected as the SX460 manual describes. I can't imagine why this test, properly conducted, would smoke an SX460. Unless, of course your field is under 15 ohms, you had the diode installed wrong, connected the 12V to the wrong place, or your field needs more than the SX460's 4 amp rating.

What is your field resistance? And how much current does the field need?
Everything was connected correctly, field was 30ohms. I have no clue what the field other requires other than I=V/R




Quote:
Originally Posted by Jim McIntyre View Post
For what it's worth, I've used SX460's on several brushless sets, and never needed to flash them, not even once. I have a hunch that the field polarity matters, and it's not obvious that reversing it will do any damage on the brushless sets I'm familiar with. So, if you understand the risks, it might be worth swapping the F+ and F- drive to your static field coil.
I tried swapping the field polarity, same lack of magnetism.
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