A $$4$$ pole dynamo with wave wound armature has $$51$$ slots containing $$20$$ conductors in each slot. The induced $$emf$$ is $$357$$ volts and the speed is $$5800$$ $$rpm$$. The flux per pole will be

The function of oil in a transformer is

Auto-transformer is used in transmission and distribution

Keeping in view the requirement of parallel operation, which of the $$3$$-phase connections given below are possible?