If an increase in speed is desired, the SCR must be turned on to apply large pulses of instant power, and when lower speeds are desired, power is removed and a gradual coasting down in speed occurs.

• 发动机低速转动时需要连续的窄脉冲流维持速度。当需要提高速度时，必需开启SCR，产生瞬间大功率脉冲；当需要降低速度时，SCR会降低功率，从而逐渐降低速度。