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Author Topic: What changed ??  (Read 6404 times)

potter

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What changed ??
« on: December 11, 2014, 11:49:17 AM »

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Generator output what changed???

« on: Today at 04:22:02 AM »


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Hi all could sure use some help, I have been using a lister sr1 with a Brush gen head as a construction gen set.
It has run all the tools fine for about three weeks until a few days ago the air compressor at times would load up and not start, this
got progressively worse until it now will not start at all.
It will no longer run the table saw which it ran fine until this happened with the air compressor. All the other tools run fine including a second air compressor that is also capacitor start.
I have put my Kill a watt on it and the output is the same as before this happened 124 volts at 62.5 hz no load.
Could sure use any tips on what I could check, everything else it seems to run just fine with no loss of power.





dieselgman

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Re: What changed ??
« Reply #1 on: December 11, 2014, 12:01:57 PM »
I would first take a careful look at the brushes inside the genhead. A key piece of information that is missing from your post - what load currents are you reading? (specifically for the equipment that you can no longer start up).

What does the genny do when the heavy loads are applied? How much voltage drop at the loads?

dieselgman
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potter

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Re: What changed ??
« Reply #2 on: December 11, 2014, 02:24:17 PM »
sorry the voltage drops down to 97 volts when trying to start them the table saw blade oscillates back and forth the air compressor is only a small portable the other one that it runs fine is twice the size and rated wattage.

Thob

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Re: What changed ??
« Reply #3 on: December 12, 2014, 01:28:26 AM »
Does the engine slow down and grunt a lot, lots of black smoke (diesel?), etc?  Or does the engine sound like it's running along just fine?  Check the Hz with the kill-a-watt and see if it's loosing RPM under load, that will make it hard to maintain the voltage.

If the engine isn't slowing down a lot, then it sounds like you've lost voltage regulation.  Does it have an AVR?
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potter

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Re: What changed ??
« Reply #4 on: December 12, 2014, 11:25:30 AM »
   Thanks Thob yes the RPM does drop and no it does not have a AVR it only has an aux field winding and a bridge rectifier I am now thinking the aux field winding must be shorting .I have cleaned the slip rings and not much more to blame >:(

ronmar

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Re: What changed ??
« Reply #5 on: December 12, 2014, 09:16:42 PM »
I didn't notice if you said this was a regulator equipped gneerator head or harmonically/capacitor regulated?  IF harmonic, are you still using the original bridge rectifyer?  The original on mine was a board with individual diodes connected in a matrix.  If one of the diodes has failed or become disconnected this would limit your output, particularly under load.  IF a diode shorted, it would cause more noise/pulse in the output.   There are far better quality bridge rectifiers out there and they are not very expensive.  Surplus center usually has them cheap, I will edit a link in below.

One of these should work.  I replaced mine first thing and bought a spare just in case...
http://www.surpluscenter.com/Electrical/Transformers-Bridge-Rectifiers/Bridge-Rectifiers/35-AMP-1000-VOLT-KBPC3510-BRIDGE-RECTIFIER-22-1206.axd
« Last Edit: December 12, 2014, 09:22:30 PM by ronmar »
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potter

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Re: What changed ??
« Reply #6 on: December 12, 2014, 09:47:35 PM »
Thanks ronmar I do have a few bridges on hand and will give a new one a try but it will be a few days before I can get to it .

   Thanks  Chris

Horsepoor

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Re: What changed ??
« Reply #7 on: December 14, 2014, 03:46:29 AM »
I buy mine at MPJA.com and they happen to be on sale at half the price.
http://www.mpja.com/mobile/50A-1KV-Bridge-Rectifier-KBPC50-10/productinfo/31094%20BR/
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potter

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Re: What changed ??
« Reply #8 on: December 17, 2014, 09:45:27 AM »
Thanks guys finally got a chance to check the gen, It was the bridge rectifier all is running well again. ;D

   Chris