Diagram of LV DPT starting in one stage as a function of time and dynamic braking in EMF function

When the start button SB2 is pressed, power is supplied to the coil of the electromagnetic relay KM3, after which the coil of the relay becomes self-energized using its contact KM3.4, which shunts the start button SB2. In this case, the blocking contact KM3.3 is opened to prevent the voltage relay coil KV1 from turning on and the power contact KM3.1 is closed, which leads to the start of the motor M1. Until the contact of the electromagnetic relay KM2 is activated, the armature of the motor M1 is fed through the resistor R2, that is, the motor operates in the first stage. Time switch KT1 operates after closing of contact KM3.2 and after specified time delay its contact KT1 is closed. The relay coil KM2 is energized via contact KT1 after a time equal to the time delay of the time relay. Actuation of the electromagnetic relay KM2 leads to the closure of its contact KM2, which shunts the resistor R2, the armature of the motor M1 receives power directly, the motor goes to the second stage. When the stop button SB1 is pressed, the relay coil KM3 stops receiving power, its contacts return to the initial position, after which the coils of electromagnetic relay KM2 and time relay KT1 also do not receive power, their contacts also return to the initial position. Opening of KM3.1 contact turns off power supply of engine armature. Since the contact KM3.3 of the relay KM3 is closed, the voltage relay KV1 receives power from an armature in which current is induced due to its rotation in the magnetic field of the excitation winding of the OS of the motor M1. After actuation of the voltage relay KV1, its contact KV1 is closed, supplying power to the coil of the electromagnetic relay KM1, which in turn closes its contact KM1, which makes a parallel connection of the resistor R1 to the armature circuit of the motor M1. This resistor limits the current passing through the circle of armature windings. This current creates a magnetic field around the armature windings, which counteracts the magnetic field of the OS excitation winding. This results in a brake torque. After the armature stops, the current in its circle disappears, the windings of relays KV1 and KM1 cease to receive power and their contacts return to their original position.