Originally posted by Ufopolitics
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Originally posted by Ufopolitics
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@UFO
It is my understanding that we have agreed on all the critical angles making up the connect/disconnect sequence including the 'final agreement' which was including the brush width in the calculation...the sweep angle...the roll off angle or what ever we want to call it.
We are both at a disadvantage, it seems, by not having the complete motor specs. But in fact the only critical spec missing from this 10 pole arrangement is the brush width which is very important. A 36º comm segment will sweep over an 18º brush from 1º ON to 0º OFF in 53º. A 36º comm segment will sweep over a 36º brush from 1º ON to 0º OFF in 71º.
If the sweep angle is 53º then there is 37º for connect and disconnect. Firing at 27º or 20º leaves a 10º or 17º disconnect.
If the sweep angle is 71º then there is 19º for connect and disconnect. I think we can see there is an issue with this structure.
The position of the brush is unimportant. The size of the brush can be critical.
For your second image, C2 has just disconnected at 21º from the SSB, C1 is therefore 36º + 21º = 57º back from the SSB. The brush appears to be 18º wide. To obtain the connection angle we need to back up the coil by 18º. This places the C1 bisector 36º + 18º + 21º = 75º back from the SSB, 15º forward of the NSB.
The timing margin appears to be 10º assuming a minimum 5º firing angle.
If it transpires that the brush is not 18º but 36º then we lose the margin and find ourselves in a deficit of 3º.
If Sam can confirm the brush width then we will know for certain what is achievable with this motor.
Happy Hunting
mark
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