SU29897A1 - The method of zero-directional start-up of a three-phase asynchronous motor with rings - Google Patents

Description

The present invention relates to the field of zero-down start-up of three-phase asynchronous motors. As is well known, a normal asynchronous motor is floated using a starting rheostat, which costs up to 100 horses for a generator. The forces range from 10 to 20% of the engine cost. Therefore, the use of the system, which makes it possible to start without a trigger, greatly reduces the cost of installation and gives great savings in non-ferrous metals, which in large quantities are used to manufacture starting resistors.

Most of the still-free start-and-connection schemes of Gerges and Schwnfer that have been proposed, the dual power supply of Dparov and so on, require special windings. The proposed scheme can be applied to a normal asynchronous motor connected to a star, in the stator winding of which only a few are made during: connections.

The proposed connection scheme for the windings of a three-phase asynchronous motor is shown in the drawing, where / is the stator winding, 2-rotor winding, 3 is a bipolar short-circuit switch. When the motor is turned on, the two ends of the rotor winding are connected between the zero point, the stator windings

15b):

H end of one of the phases of the latter. The third end of the rotor winding, which is disconnected from the zero point, comes to some intermediate lead from one of the two stator phase windings interconnected. After powering on and accelerating the engine, all three ends of the stator winding are shorted to zero point using the knife switch 3. At the same time, the brushes are raised and the rotor rings are short-circuited. Thus, as can be seen from the above, it is proposed to use a mixed connection of the stator windings of the rotor, wherein the circuit is chosen in such a way that the resistance of the windings themselves plays the role of a starting resistor.

According to the authors, when starting up in this way, for motors with different numbers of slots in the stator and rotor, a good starting torque and starting current that does not go beyond normal limits are obtained.

The subject matter of the invention.

The method of zero-free start-up of a three-phase asynchronous motor with rings and windings connected to a star, characterized in that when the motor is connected to the network, the two ends of the rotor winding are connected between

.iulevby point of the stator winding and the end of one of the phases of the latter, disconnected from the specified zero point, the third end of the rotor winding to any intermediate branch from one of the two stator phase windings interconnected

switching on and unwinding the motor short-circuits all three ends of the stator winding to the zero point with the help of a short-circuited two-pole knife switch 3 and at the same time raise the brushes short-circuited the rotor ring.

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