Help understanding a GE tapchanger

[stevenal]

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1671143998/tips/DOC005_cvrzwk.pdf[/url]

Can anyone help me understand the purpose of the 84X/TDO normally closed contact and the diode on the right side of this drawing? The two resistors brake the motor once it gets on step, but the midpoint connection confuses me. This seems to be a common GE design. Thanks.

 

[pwrengrds]

Motor inrush reduction circuit.

 

[stevenal]

I fail to see how it can reduce inrush. When on step (33 is closed) the 84X contact is open. The contact closes once it is off step, but I would expect the inrush to be over by then.

 

[stevenal]

I believe the diode provides DC for braking. 84X/TDO opens 1s after it gets back on step, taking the diode out of the circuit.