The power supplied by utility company should be satisfactory. The polyphase voltage supplied at consumer terminals should be balanced. If that is not the case and some unbalanced polyphase voltage is supplied to a consumer operating synchronous or induction motors, the result will be a decreased efficiency of power machinery and it will also have a decrease in the maximum power output.
Electrical motors when called upon to deliver full load when their terminal voltages are unbalanced are exposed to considerable damage due to overheating that takes place.