The simplest and cheapest method of starting an engine is undoubtedly the direct starting, but in this method, the current takes on extremely high values, being between 4 and 12 times the value of the nominal current, which forces the person in charge of the system electrical power to oversize the power system, circuit breakers, fuses, and other devices that are an integral part of the electrical circuitry https://www.mrosupply.com/motors/dc-motors/washdown-motors/2525647_11301900_leeson/ that powers the motor. Alternative methods that decrease direct startup can be achieved with the use of contactors and timers.
Two types of MIT starters that use this technique are star-delta starters and compensatory starters, based on autotransformers. In both the star-delta starter and the starter with compensating switch, the electric motor starts at reduced voltage and the instant at which the rated voltage is applied to the motor occurs at about 80% (self-compensating) and 90% -Δ) so that the current peak is decreased. The compensating switch can be used for starter motors under load, where the star-delta switch is inadequate. With it, we can reduce the starting current, avoiding overload in the mains, leaving, however, the motor with a sufficient torque for acceleration and starting.