Final answer:
Changing the rotation of a three-phase bank can have significant effects on a customer, particularly in causing three-phase motors to run in reverse and creating power quality issues. Doubling the frequency of rotation in a generator doubles the output emf, potentially affecting the electricity supply if not properly managed.
Step-by-step explanation:
If the rotation of a three-phase bank was changed, the effect it would have on the customer depends on how the rotation change impacts the generator connected to the three-phase system. In an electrical generator, the electromagnetic force (emf) generated is dependent on several factors, including the speed of rotation. When the frequency of rotation of a generator's coil is doubled, this will result in the output emf also doubling, assuming that all other factors remain constant. This is due to Faraday's Law of electromagnetic induction, which states that the emf induced is directly proportional to the rate of change of the magnetic flux linkage or, in simpler terms, the speed of rotation of the coil in the magnetic field.
However, when we consider a real-world scenario, such as the operation of a three-phase power system that is used to supply electricity to a customer, changing the phase rotation (or phase sequence) could cause a problem with any three-phase motors that the customer may have. If the phase rotation is incorrect, motors can run in reverse, potentially causing equipment damage and safety risks. It would also affect any equipment that relies on the phase sequence for proper operation.