autotransformer open circuit vs closed circuit

[jbouverette]

just a simple question,

what does the diagram for a 3p open circuit transition autotransformer look like? are the neutrals permanently wired together?

i am fully aware of the drawbacks, found plenty of info on closed circuit but none on open circuit. thanx

 

[jraef]

If by "neutrals" you mean the star point of the transformer, then yes. Here is a link that shows a diagramatic comparison of the open transition and the Korndorfer closed transition type. For the closed transition they use a manually operated starter to illustrate the point, but you can just substitute electro-mech contactors if you like.

http://www.seamanship.co.uk/engineering/EKsamplepages/Motor starters.htm

"Venditori de oleum-vipera non vigere excordis populi"