FIELD: electrical engineering. SUBSTANCE: a.c. drive has induction motor 1, starting and running capacitors 2 and 3, magnetic starter 4 with make contact groups 5,6,7, START buttons with contact groups 8 and 9, and STOP button with contact group 10. Pushing START button makes magnetic starter 4 operate, and supply voltage is applied to motor 1. While START button is ON, starting capacitor 2 is energized. START button is released after motor 1 gains rated speed. This de-energized starting capacitor 2. Electric motor runs with running capacitor 3 energized. ON-state of magnetic starter 4 is attained due to self-holding of starter coil by make contact 5. For stopping motor 1 STOP button 10 should be pushed. EFFECT: improved performance characteristics due to improved reliability as result of reduced quality of contact members passing starting current; improved efficiency due to reduced number of contact resistors inserted during starting movement. 1 dwg
