Direct start is the starting system in which the electric motor receives full voltage at the moment of departure. The cage rotor motor can start motor frame at full load and with current rising from four to eight times the rated current, according to type and number of poles. The conjugate at the starting reaches approximately 1.5 times the nominal torque. The factors that prevent the starting of the motors directly from the secondary network are the power of the motor is higher than the maximum allowed by the local concessionaire and the load to be moved, it requires slow and progressive drive.
This is the simplest starting method since no special motor drive devices are used. Only contactors, circuit breakers or switch switches are used which allow the motor to be supplied with full voltage at the moment of starting. The motors can only be started directly from the mains if the following conditions are met, the rated capacity of the mains is satisfactorily high so as to make the motor starting current irrelevant, the starting current of the motor being of low value because its power is and the starting of the motor is done without load, which reduces the duration of the starting current.