Originally Posted by
T-Man
Rotation and phase angle and position are two different parts of three phase transformer wiring. You can change rotation by changing two primary phases or messing with the secondary connections. Delta is a three wire connection, usually 240 or 477 voltages. Wye connections are 4 wire connections that include a neutral grounded leg and the 3 phase voltage is usually 208 or 416. Customers that use three phase should have motors or equipment that is designed to operate in one direction, so finding rotation is important. in future applications it's a good policy to mark rotation in a convenient location so if you change out the source you know which way to set up the new set. You can turn off all the breakers on the customers side then energize the tub and only turn on one breaker to one motor to see if it turns in the correct direction. Usually larger 3 phase motors have an arrow on their case showing their correct rotation. Wye and Delta can rotate in the same direction the voltage may be a problem in some cases. You can use vectoring, rotation meters, and trial and error as long as your not damaging customer equipment.