Final answer:
An imbalance in phase-to-phase voltage can lead to decreased efficiency due to asymmetric load distribution and increased power dissipation, causing excess heat and stress.
Step-by-step explanation:
A small imbalance in phase-to-phase voltage can result in decreased efficiency. This is because such an imbalance typically causes an asymmetrical loading and distribution of power, which in turn can increase power dissipation in the system. An imbalance can cause excessive heat, increased stress on electrical components, and can lead to a variety of undesirable effects that reduce the overall efficiency of an electrical system. Moreover, electrical devices are designed to operate optimally within specific voltage ranges, and when these are not maintained, both performance and efficiency can suffer.