Model Train Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
2,085 Posts
Discussion Starter #1
Before I tear a loco apart ....

On a pre/post war AC motor, if you disconnect the field winding from the frame, would the motor (field & brushes) be electrically isolated from both sides of rail power? Seems like it would but I though I get a second opinion.
 

·
Registered
Joined
·
2,527 Posts
Perhaps this will help you? I believe the answer to your question would be a yes that removing the frame connection from the field coil would isolate the motor as it would only be connected to the hot center rail at that point.

Edit: that also depends on how the locomotive is wired. I believe they're typically wired as in the diagram below, but in some cases such as the 1654 2-4-2 locomotive, one of the brushes is actually grounded to the frame instead.

 

·
Registered
Joined
·
2,085 Posts
Discussion Starter #3
Perhaps this will help you? I believe the answer to your question would be a yes that removing the frame connection from the field coil would isolate the motor as it would only be connected to the hot center rail at that point.

Edit: that also depends on how the locomotive is wired. I believe they're typically wired as in the diagram below, but in some cases such as the 1654 2-4-2 locomotive, one of the brushes is actually grounded to the frame instead.

I agree. A field wire can be detached. A frame grounded brush would preclude isolation the motor

And I would need to ensure the E-unit's coil grounding vis-a-vis ithe drum motor connections. But they should be isolated by default.
 

·
Registered
Joined
·
8,854 Posts
Others have already answered, but yes, removing the field wire should do it.
 
1 - 4 of 4 Posts
Top