Re: AC Split phase motor????

["R.E.Burnett" <R.E.Burnett-at-xxxxxxxxxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Thanks Bert,

It sounds like you nailed it.  The instantaneous HV on the motor case
probably found the nearby mains windings very tempting !

This is one reason why I connect my motor chassis to the utility ground
instead of the RF ground.  The RF ground is very noisy when the coil is
running,  and this must put considerable stress on the insulation between
the case and the windings.

I opened up the damaged motor,  but unfortunately the run winding of
my motor had opened deep inside the stator,  and I didn't have the
patience to rewind it.  I agree about the follow-through current.

						Cheers,

						-Richie,


> Original poster: "Bert Hickman" <bert.hickman-at-aquila-dot-net> 
> 
> [snip] 
> 
> In the case of your motors, I wonder if a sudden power arc hitting the
> grounded motor might have been sufficient to generate a short, high
> voltage transient on the case of the motor due to the presence of lead
> inductance between the motor and true RF ground. If this transient was
> sufficient to cause a flashover between the elevated case and a stator
> winding, the resulting follow-through current from the LV mains to
> ground might blow open up the connection to a winding at the point of
> the flashover. Depending upon where the open occurs, the motor might be
> easily repairable without rewinding.
> 
> -- Bert --
> Bert Hickman
> Stoneridge Engineering
> Email:    bert.hickman-at-aquila-dot-net
> Web Site: http://www.teslamania-dot-com