Y-△ voltage reduction control circuit controlled by DC relay

After the power switch is turned on in this circuit, the motor will not start immediately, but will be delayed for a specified period of time, which can be used for automatic intermittent lubrication of machine tools
    . The usual Y-shaped starter is controlled by a time relay. The shortcoming of the timer electrical control is that it cannot
automatically adjust the starting time as the load changes. The Y-△ starter controlled by DC relay can automatically adjust the starting
time within a certain range according to the load. The Y-△ pressure reducing starting circuit controlled by
    DC relay is shown in Figure 4-32. Press the start button SB2, the contactor KM1 is electrically attracted, and at
the same time, the contactor KM2 is also electrically attracted and self-locking, the main contacts of KM1 and KM2 are closed, and the motor is connected in a Y shape to reduce pressure and start. DC relay
Kl is affected by the starting current and immediately pulls in. One set of its normally open contacts closes to ensure that KM1 closes, and the other set of moving contacts closes to
electrically pull in the time relay KT. When the current drops to the rated value, KI loses power and is released, and KM1 is released immediately. The KM1 movable contact is disconnected, causing the contactor KM3
to be electrically closed. The motor is connected in a △ shape and runs under full pressure. When stopping, just press the stop button SB1.
    The function of KT delayed disconnection contact is to ensure that KM1 will be disconnected when Kl cannot be released due to fault, and its time limit setting must be greater than
the maximum starting time of the motor.