In some places, allowing only a specific direction by the motor running, even when the power supply phase sequence
for some reason (such as outside line after overhaul wrong) while inverted, but also to ensure that the motor running in the specified direction. Otherwise, it will cause physical and equipment do so. The phase sequence can be used for this determination is to be controlled. Circuit shown in Figure 3-90. When the power supply phase sequence is correct, that is, U, V, W phase sequence when, Ne neon bulb does not light, relay device KA pull, press the start button SBi, contact KMi pull the motor starts running forward. If the power supply phase sequence right, Ne shiny, KA released. Press SBi, KMz suction units, the motor will change the phase sequence followed by people power, the motor still running forward start.