BLOG

How to connect the five speed control wires on a variable-speed motor

Release time:

2026-03-24

The wiring of the five control wires for a speed-controlled motor must be determined based on the motor type (single-phase/three-phase) and control method.

The wiring of the five control wires for a speed-controlled motor must be determined based on the motor type (single-phase/three-phase) and control method. A common configuration consists of three power wires (U/V/W) and two control wires (P/N or +10V/COM). Correct connection is key to achieving smooth speed control.

For three-phase variable-speed motors, the five wires typically consist of three phase wires (U, V, W) and two control signal wires (P, N). When wiring, connect U, V, and W to the speed controller’s output terminals L1, L2, and L3, respectively; connect P (+10V) to the speed controller’s analog input terminal; and connect N (COM) to ground to enable speed signal control. Some models may use star or delta connections: the star connection shorts the three winding ends together, suitable for low-voltage starting; the delta connection connects the ends in a closed loop, suitable for high-torque operation.

For single-phase speed-controlled motors (such as electric fan motors), the five wires are typically the common wire (black), high speed (red), medium speed (white), low speed (blue), and start wire (yellow). In this case, first connect the black wire to the yellow wire via a capacitor, connect the black wire to the neutral wire, and connect the red, white, and blue wires to the live wire via a switch to achieve multi-speed control. You can use a multimeter to measure resistance and determine the connections: the two wires with the highest resistance should be connected to the capacitor, and the wire with the lowest resistance corresponds to the high-speed setting.

Regardless of the wiring method, always disconnect the power supply before proceeding, and refer to the equipment manual to confirm the wire sequence to avoid motor damage caused by reverse wiring. Interface definitions may vary between different brands of speed controllers; for example, if +10V and COM are used to receive external speed control signals, they must be matched with the controller.

Back

Recent information