AC contactor power-saving silent operation circuit (4)

The circuit shown in the figure is an application example of achieving high-voltage (380V) starting and low-voltage (220V) operation of the AC contactor in a manual Y-△ step-down starter, achieving energy-saving and silent effects. When the start button ST is pressed, it will be powered for 1km, and its normally open contact will be closed, and it will be powered for 3km. The 3KM normally closed auxiliary contact is opened, the main contact is closed, and the M winding of the motor is connected in a Y-shaped connection for voltage reduction start. When the motor speed reaches or approaches the rated speed, press the run button STN to cause 3KM to lose power and release, 2KM to gain power (380V) to pull in, and motor M switches from Y connection to △ connection operation. Almost at the same time, the normally closed auxiliary contact of 2KM acts to cut off the power supply L3ˊ, and the normally open auxiliary contact connects the center line N, causing the 2KM coil to change from high voltage (380V) to low voltage (220V), achieving silent power-saving operation.