![GATE EE 2010 Electrical Machines - Transformers Question 58 English](https://gateclass.cdn.examgoal.net/examside/questions/07216ea2bb4495b59e98899d60125946086e5629e0213e8031ff24025e84f40c.jpg)
![GATE EE 2009 Electrical Machines - Transformers Question 21 English](https://imagex.cdn.examgoal.net/HJhQzeEgPV6YpoVxw/XG7cx4VtWOfRaWa9XSDgUAoErEQf7/5KNLOEq61Rtia6ip9Jjkpa/image.png)
The figure above shows coil $$1$$ and $$2,$$ with dot markings as shown, having $$4000$$ and $$6000$$ turns respectively. Both the coils have a rated current of $$25$$ $$A.$$ Coil $$1$$ is excited with single phase, $$400$$ $$V,$$ $$50$$ $$Hz$$ supply.
In the auto-transformer obtained in Question $$30,$$ the current in each coil is
![GATE EE 2009 Electrical Machines - Transformers Question 22 English](https://imagex.cdn.examgoal.net/HJhQzeEgPV6YpoVxw/XG7cx4VtWOfRaWa9XSDgUAoErEQf7/5KNLOEq61Rtia6ip9Jjkpa/image.png)
The figure above shows coil $$1$$ and $$2,$$ with dot markings as shown, having $$4000$$ and $$6000$$ turns respectively. Both the coils have a rated current of $$25$$ $$A.$$ Coil $$1$$ is excited with single phase, $$400$$ $$V,$$ $$50$$ $$Hz$$ supply.
The coils are to be connected to obtain a single-phase, $${{400} \over {1000}}\,\,V,$$ auto-transformer to drive a load of $$10$$ $$kVA.$$ Which of the options given should be exercised to realize the required auto-transformer?