SOLUTION

A synchronous motor is said to be ‘floating’ when it operates at no load and without losses.

Floating in Synchronous machine

Suppose that a synchronous machine is driven by a prime-mover and its stator windings are connected to a three-phase ac supply. The operation of the machine is synchronized such that no current flows through its stator windings. Under this condition, the excitation emf E in the armature windings is exactly equal to the bus-bar voltage V. The machine is neither receiving nor delivering any power to the bus bar. It is the prime-mover that supplies power to meet the losses in the machine, Under this condition, we say that the synchronous machine is floating on the bus bar.

or

When synchronized, the generated emf of the incoming machine is just equal to the bus-bar voltage. The synchronous machine will be just Floating on the bus bar, i.e. it will neither deliver nor receive any power. The prime mover driving the machine will be supplying the no-load losses only.