Rated voltage is the working voltage of the motor under normal conditions, it must not be extrapolated over long periods of time, in the event of damage to the motor; is the design voltage of the motor. By the old NBR 7094 standard, the entire electric motor must be able to operate satisfactorily when supplied with both voltage 10% below and 10% above rated voltage, provided the frequency is rated. The new standard NBR 7094 establishes a new system for the operation of the motor under frequency and voltage with deviations from the nominal values 6004 ZJEM. The combination of frequency and voltage variations is framed in two zones: A and B.

The motor must be able to operate continuously in zone A, but with some deviations in the rated characteristics. The temperature rise may also be higher than that which would occur in normal operation. In zone B, the engine must also be able to operate for a limited time, however, with deviations higher than those in zone A and with a higher temperature rise. In both operating zones, the engine must be capable of delivering its nominal torque.