SU1206874A1 - Device for protection of electric machine converter against wire breaks - Google Patents

Description

The invention relates to an electrical equipment and is intended to protect an electric motor converter from a motor-generator against accidental increases in the rotational frequency, which could be caused by a break in the bottom of the motor excitation windings.

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The aim of the invention is to improve the accuracy of operation by eliminating the influence of the output voltage of the generator on the response threshold, simplifying the setting, reducing the mass and. device dimensions.

Fig. 1 shows a diagram of the proposed device j in Fig. 2 — time diagrams of its operation.

The ddk protection device from over-speeding of a motor-converter with a driving motor 1 and synchronous generator 2, equipped with an automatic regulator 3 of the rotation frequency and actuator 4 with a protection circuit, providing connection of the electric motor 1 to the power supply, network 5, contains the first transformer b, primary winding 7 of which is connected to the output of the synchronous generator 2, and the secondary winding 8. its first output is connected to the first output of the LC circuit 9, consisting of successively connected droplets 10 and 11. The capacitor device comprises actuating switch 12, winding 13 is shunted by the smoothing capacitor 14 and the terminal 15 is turned on and the protection circuit

starter 4. The device has the first 16 and second 17 thyristors and saturation of the second transformer 18 5 through the primary wrapping 19 of which the second output of the LC circuit 9 connects to the second output of the secondary winding 8 of the first transformer 6, to the midpoint of which the first winding 13 of the actuator is connected relay 12, the second output connected to the middle point of the secondary winding 20 of the second transformer 18, through the cathode-anode p: First thyristor 16 - to the first output

and through the cathode-anode of the second thyristor 17 to the second output of the secondary winding 8 of the first transformer 6, while the first output of the secondary winding 20 of the second transformer is connected to the control elec- trode:

0

five

0

five

0

the first 16 thyristor, and its second output - with the control electrode of the second 17 thyristor. The starter 4 is provided with a protection circuit providing automatic shutdown of the electric motor from the supply mains in the event of an emergency mode, as well as the Start and Stop buttons for manual switching on and off of the electric motor.

The device works as follows.

After connecting the electric motor 1 to the mains supply 5 by means of the starter 4, a variable voltage appears at the output of the synchronous generator 2, the frequency of which is maintained at a predetermined level by the automatic rotation speed regulator 3. The output voltage of the generator 2 is fed to the input of the primary winding 7 of the first transformer 6, while the secondary winding 8 of the first transformer is induced

, EMF, and the primary winding 19 of the second transformer 18 flows an electric current, inducing the EMF in the secondary winding 20 of the second transformer.

FIG. 2 shows the graphs: a — voltages on the secondary winding 8 of the transformer 6; b - LC circuit current 9 flowing through the primary winding 19 of the second transformer. 18; in - current pulses in the secondary winding 20 of the second transformer 18, - supplied to the control electrodes of the thyristors 16 and 17; d - voltage supplied to the winding 13 of the executive relay 12.

During normal operation of the converter with a rotational speed not exceeding the nominal value

five

O

with

II ohm

), unlocking pulses

(The yokes in the control electrodes of thyristors 16 and 17 (Fig. 2c) coincide with negative voltage half-periods on the anodes of these thyristors (Fig. 2a). The thyristors remain closed, the winding of the relay 12 is de-energized. Motor 1 is connected to mains 5.

With increasing rotation frequency of the converter above the nominal

55 values (fJ with

IOM

)

unlocking

current pulses in the control electrodes of thyristors 16 and 17 are the same j

give with positive half cycles

voltages on their anodes. The thyristors are unlocked, the relay 12 is triggered by the action of a voltage applied to the winding 13 (Fig. 2d), the contact 13 is opened, breaking the protection circuit of the actuator 4. The electric motor 1 is disconnected from the power supply network 5.

12068744

The positive effect of the invention is to increase the accuracy of the protection device, which is determined by the stability of the resonant frequency of the LC circuit and does not depend on the magnitude of the generator voltage, as well as simplifying the tuning and reducing the mass and dimensions of the device.

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Editor G. Volkova

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Compiled by O. Orlov

Tehred M. Parotsay Proofreader L. Pilipenko

Order 8726/55 Circulation t1 i Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch GOSH Patent, Uzhgorod, Proektna St., 4

Claims (1)

DEVICE FOR PROTECTION AGAINST OVER ROTATION FREQUENCY OF THE ELECTROMECHANICAL CONVERTER of the type electric motor-generator, equipped with an automatic speed controller and a starter with a protection circuit that connects the electric motor to the mains supply, containing the first transformer, the primary winding of which is connected to the output of the generator the first output is connected to the first output of the LC circuit, consisting of, simplifying the understatement of the mass and dimensions, introduced the first, second tirysaturated second t ansforcherez kotoposledovatelno primary winding connected inductor and capacitor, and the output relay, the winding of which is shunted by the smoothing capacitor and including The contact ~. it is included in the starter protection circuit, characterized in that, in order to increase the accuracy of operation by eliminating the influence of the value of · the generator output voltage on the trigger threshold of the swarm, it has torus; and the mater, the second output of the LC circuit, is connected to the second output of the secondary winding of the first transformer, to the midpoint of which the first output of the actuator relay is connected, the second output connected to the midpoint of the secondary of the second transformer, through the cathode-anode of the first thyristor to the first output and through the cathode-anode of the second thyristor to the second terminal of the secondary winding of the first transformer, while the first terminal of the secondary winding of the second transformer is connected to the control electrode of the first, and its second output is the gate electrode of the second thyristor. Q