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The direction of rotation of an electric motor can be changed anytime and easily at the motor terminals. In three-phase motors, the windings configuration can easily be changed from a star or Y connection to a delta or mesh connection at the motor terminal box.
Three-phase Electric Motors
The windings of AC motors can either be connected in star(Y)-connection or in delta(Δ)-connection.The standard that deals with this winding connection and designated marking of the terminal box is IEC 60034-8. According to this standard, the phases of motor windings are defined by W, U, V
Star or Y Connection
Short-circuit the terminals W2, U2 and V2 and connect the mains to the W1, U1 and V1 to get a star(Y)-connection. See diagram below:
Delta(Δ) Connection
When connecting the end of a phase to the start of another phase you get a delta(Δ)-connection. Connect W2 to U1, U2 to V2, V1 to W1 as shown below:
How to Change the Rotation of a Three-phase Electric Motor
The direction of rotation for the motor shaft of an AC motor is defined in IEC 60034-8 as either CW (clockwise) or CCW (counter-clockwise), when looking into the motor shaft. The direction of rotation of a three-phase AC motor can be changed at the terminal box. This is done by interchanging two of the line cables, e.g switch L1 and L2.
When dealing with a single-phase motor, YOU MUST ALWAYS CHECK the wiring diagram from the manufacturer's manual to get direction on how to change the direction of rotation of the motor.
