Why does a 3 phase motor change its direction of rotation when changing any tow phases?

changing sequnce of wireconnection actually change the path of flow of current in the primary circuit which in turn change the direction of magnetic feild in the core so the direction of motion of motor chnges from clock to anti clock or vice versa

A3 phase motor has three windings by applying electricity we create three magnetic fields with120 degrees apart causing the induction motion to change direction you can simply change the input power sequence meaning that change the magnetic field direction and thats what we are using during control a motor to be operated in both directions.

A simple way of understanding why this happens is this -  The direction of rotation in a3 phase motor depends upon the sequence in which the magntic poles are created by the respective phase lines. This inturn creates a rotating magnetic field.  By interchanging any two phases (lines) the sequence of pole formation is being changed ie, the direction of the rotating magnetic field is reversed. Hence the direction of rotation of the motor also changes accordingly. Hope this helps.

The direction of the rotating magnetic field is reversed which cause the direction of rotor rotation to change

If the3 phase motor is fed with3 phase wires only meaning it is internally connected in Star (wye) or Delta then swapping over2 of the3 supply wires will reverse the rotation. For single phase motors it depends on the type of motor. Certain single phase motors such as permanent capacitor or shaded pole motors are not built to be reversed and are often fitted to equipment such as fans and pumps that do not require reversing Where a3 phase motor has3 windings - single phase induction motors usually have2 windings, a run winding connected all the time and a start or auxiliary winding that is only connected for a few seconds at start up. to Reverse a single phase induction motor the flow of current in one of the windings needs to be reversed not both so reversing the supply will not work. As both windings are effectively in parallel when supply is switched on. In a universal series motor which used brushes and has a field winding and an armature winding again reverse the flow of current in one of the windings to reverse the direction. This motor is typically used in power tools especially the power drill which often has a reversing switch on it. The previous answers saying reversing of a AC single phase motor is not possible are wrong the answerers are obviously not familiar with the various different types of single phase motors available.

In case of two phase changing, the megnatic flux direction is changed that's why the motors rotation is changed

The magnetic field rotation direction will be changed

because the magenitc field was reversed

When any two phases of three phase motor interchanged the direction of rotation of rotating flux will reverse reversing the rotation direction.

The3 phases RYB are120 degrees apart from each other in the sequence R to Y to B which form a circular rotation in clockwise or anti clockwise direction.  

Therefore, changing the sequence will reverse the direction of rotation.

Three motor has3 winding on the stator that if the rotor run can effect build induction magnet that raise rotation..the3 winding has pole position when they start to end of wire...if the direction opposite to connect that it make a change direction rotation because the way of induction magnet is opposite.