Phase sequence indicator circuit made with incandescent lamp and capacitor

Some equipment does not allow the motor to reverse, which requires phase sequence identification during installation to ensure that the motor wiring is correct. The phase sequence indicator as shown in the figure is simple and easy to make. First, clamp one of the insulated handle alligator clips to one phase of the power supply as the starting phase L1 for determining the phase sequence. The other two alligator clips with insulated handles only need to touch the other two phases of the power supply. The phase sequence of the power supply can be determined through the difference in brightness of the two light bulbs. Assume that after connecting the wires as shown in the figure, the light bulb that lights up is the L2 phase. The dimmed light bulb is the L3 phase. When making, the capacity of C cannot be selected too large, otherwise the bulb will be easily burned out. Practice proves. The combination of a 1μF capacitor and two 40W bulbs is not only durable, but also has a satisfactory brightness difference between H1 and H2.