Jack_K
Member
- Messages
- 360
- Location
- Australia
One of the many generators that I have is an Ag-Tronic powered by a twin opposed briggs, Not sure on the exact capacity. The problem is that from the factory they don't appear to have ever had an AVR however one has been fitted to this one. At some stage someone must've had excitation issues so they then modified the AVR so that when it is cranking it applies 12v to the brushes. In order to do that they have connected the negative brush holder to the frame. It looks like before that there was also a button to manually excite it.
The issues I am having with it is that it occasionally needs to be restarted to excite it and it is also I believe unsafe. I can measure an uneven voltage around 115v between either L or N and earth. The generators output is a stable 230v
Based on the only diagrams I found I thought this was ok as it was made in the USA so the diagram had two 115v outputs with the frame as Neutral. I was curious as to if an RCD would function like this so I plugged in an RCD and then an RCD tester. When the tester was plugged in it seemed to load up the generator for some reason. That's when I realised something was wrong.
I did a better inspection and found that this generator was weirdly manufactured differently to a USA spec one. There is only a 230v winding not referenced to earth as well as an excitation winding.
The 115v to earth seems unsafe and I think this is all because of the AVR's lack of transformer isolation.
I have drawn a dodgy diagram which I had only intended for me to read.
I think the solution is to fit a small isolation transformer between the 230v output and the AVR. I am having a little bit of difficulty finding a suitable one though. I had originally thought of replacing the AVR however ones suitable for a separate excitation winding seem to cost more than the generator is worth. I might still end up with the same issue if the excitation problem remains.
Does anyone have any ideas or explanations?
I would like to have the windings isolated from earth and the ability to install an Earth Neutral link.
And here is the diagram for how the USA destined version would likely be like (although a later model branded as Coleman)
The issues I am having with it is that it occasionally needs to be restarted to excite it and it is also I believe unsafe. I can measure an uneven voltage around 115v between either L or N and earth. The generators output is a stable 230v
Based on the only diagrams I found I thought this was ok as it was made in the USA so the diagram had two 115v outputs with the frame as Neutral. I was curious as to if an RCD would function like this so I plugged in an RCD and then an RCD tester. When the tester was plugged in it seemed to load up the generator for some reason. That's when I realised something was wrong.
I did a better inspection and found that this generator was weirdly manufactured differently to a USA spec one. There is only a 230v winding not referenced to earth as well as an excitation winding.
The 115v to earth seems unsafe and I think this is all because of the AVR's lack of transformer isolation.
I have drawn a dodgy diagram which I had only intended for me to read.
I think the solution is to fit a small isolation transformer between the 230v output and the AVR. I am having a little bit of difficulty finding a suitable one though. I had originally thought of replacing the AVR however ones suitable for a separate excitation winding seem to cost more than the generator is worth. I might still end up with the same issue if the excitation problem remains.
Does anyone have any ideas or explanations?
I would like to have the windings isolated from earth and the ability to install an Earth Neutral link.
And here is the diagram for how the USA destined version would likely be like (although a later model branded as Coleman)
