Three phase tester - electronic rotating field direction indicator

9-60 — elektor september 1982 three phase tester -three phase tester When connecting three phase motors to the power source, confusion can arise if the cable markings are incorrect, illegible or non-existant. How do you deal with this problem? The simple answer lies in the circuit described here, where an optical indication of power on each of the three phases is provided together with an indication of the direction of motor rotation. The completed circuit is self- powered and compact and can be fitted as a permanent indicator if desired. Those of our readers who are familiar with three phase mains power supplies will no doubt be fullly aware of the confusion that can arise if, for one reason or another, the supply cables lose their identification. The problem is increased by the fact that either the motor being connected will not run at all ( in which case the fault will in- variably be blamed on the motor), or the motor will run the reverse direction. The latter case brings wi...