SU1582308A1 - Device for starting and protecting induction motor from emergency conditions - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to save energy. The goal is achieved by the fact that fully controlled two-way conductor power switches 1 in load phases, current sensors 3, pulse driver 4, two reed switch soft starters 5 and 6, and protection relay 9 are entered into the device. Normally open contacts of the first reed switch soft start are turned on diodes 13 to the control electrodes of the power switches 1. Diodes 13 are connected in parallel with the closing contacts of the second reed switch soft start. The power circuit of the protection relay includes the contacts of the thermal relay 12. 1 slug.

Description

The invention relates to electrical engineering, namely, semiconductor voltage regulators, can be used in industrial, consumer and transport electrical engineering, especially to control and protect inductive loads, simultaneously performs the functions of an electromagnetic contactor, automatic current switch, thermal relay of a compensator of reactive power .

The purpose of the invention is to save energy.

 The drawing shows a circuit diagram of a voltage regulator.

The controller contains controlled power switches of double-sided conductivity 1 connected in series with load 2, current sensors 3, pulse formers 4 connected through the normally open contacts of the first reed switch soft starter 5 to the control electrodes of power switches 1, and the winding of the relay 5 is on in series with the winding of the second reed switch soft start 6, a button with a reed blocking contact 7, a stop button, a normally closed contact 8 of the third reed switch 9, and relay 6 has a time m - specifying chain consisting of pa. parallel connected adjustable capacitor resistor. The power supply circuit of protection relay 9 in parallel includes three normally open rep-con 10, placed inside the turns of the phase conductors 11, and the relay has a timing chain similar to relay 6, thermal protection relay 12, the main element of which is a mercury thermometer having thermal contact with radiators of power switches 1. The thermometer has built-in contacts (a, b), closed by a mercury column at 60. ° C. Contacts A and B are connected in series to protection redundancy circuit 9. Two soft start relays and protection relays are reed. The diodes 13 are connected to the output of the control unit 14, consisting of a current sensor 3 and a pulse driver 4,

 The device works as follows.

First, the power voltage is applied to the power keys 1, then press

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the start button, thereby closing the trigger circuit of the soft start relay 5 and 6. Relay 5, with its contacts, switches the control pulses through diodes 13 to the power switches 1, thereby opening them only in one direction. Load 2 is connected to the network. After the operation of the relay 6, which is triggered with a delay of 0.1-1 s relative to the operation of the relay 5, the diodes 13 are turned off, thereby opening the power switches 1 completely. This ensures that the load is stepwise connected to the network, which is especially important for loads such as, for example, asynchronous motors with a squirrel-cage rotor. The current sensor 3 and the pulse shaper 4, forming the control unit 14, are used to automatically adjust the angle from / to the load (current) function, which is important for synchronous motors (idle stroke - load). With increasing load, the load current increases, which leads to a decrease in the angle d and vice versa. The result is a high load power factor in any mode.

Emergency modes. Instantaneous overload, short circuit. The current sensors are normally open reed contacts 10 placed inside the turns of the phase conductors 11. The response current of the reed switches 10 is somewhat greater than the starting current. When any of the reed switches 1Q is triggered, the operation circuit of the protection relay 9 closes, which is triggered by opening the holding circuit of relay 5 and 6. Releasing relay 5, removing impulses from control electrodes, load, 2 is disconnected from the network. Relay 9 has a time setting circuit RC for protection against false alarms.

Thermal protection with a long increase in the load current is greater than the rated current, but less than the starting current. Overload currents contribute to the release of more power to the radiators of power switches 1; The temperature of the radiators also increases at 60 ° C; Thermometer 12 (thermal relay) closes its contacts A, B, including the circuit of protection relay 9 and then everything happens as in the case of instantaneous overload.

The positive effect is achieved while simplifying the circuit, since the functions of contactless switching on and off in manual and automatic (short circuit and overload protection) modes are achieved with a constant power circuit, and reed relays and contacts are extremely simple, reliable, cheap.

Compared with the prototype, the device has the property of automatically stabilizing the power factor when the load changes by means of incomplete control power switches due to current coupling.

Claims (1)

Invention Formula A device for starting and protecting an asynchronous electric motor from emergency modes, containing a double-sided thyristor switch for connecting to the corresponding phases of the mains supply, a control unit whose inputs have terminals for plugging into the corresponding phases of the mains supply, three diodes whose anodes are connected to the corresponding the outputs of the control unit, serially connected Stop and Start buttons, characterized in that, in order to save electricity by stabilizing the power factor of the protected ektrodvigatel 82308 reed soft-start relay, the closing contacts of the third reed relay, intended for installation in the ring turns of the corresponding phases, are connected in parallel, their first output is connected through the winding of the same relay to the terminal for connecting the DC source. ten 20 to minus 1, the second terminal has a terminal for connecting a positive current source to the plus, parallel to the indicated winding, an adjustable resistor and a capacitor are connected, to the free output terminal of the Start button there is a chain of serially connected windings of the first reed switch soft start, parallel to which a second adjustable resistor and a second capacitor are included, the free terminal of the winding of the first reed switch soft starter has a terminal for connection to the positive power source, with Rim output Stop button through normally closed contact of the third reed switch is connected to the minus terminal for connecting a source of constant current H30 Nogo, thermal switch made in the form of mercury Temperature sensor intended for mounting in a radiator power switch valves, normally open contact which is included 25 when the load on the shaft and cola-jc. changes in parallel to the closing contacts of the mains voltage baths, three reed reed relays are added to it, while the closing contacts of the first reed switch of the soft start are connected between the cathodes of the diodes 40 and control transitions corresponding to the phases of the thyristor switch bilateral conduction, parallel to each diode are included the corresponding closing contacts of the second d $ dami. The third reed switch, parallel to the Start button, is on closing the contact of the first reed relay, and the control unit is made in the form of series-connected current sensors and a pulse shaper, in addition, the inputs of the current sensors are the inputs of the control unit, and the output of the pulse shaper is its output . Parallel to the closing contacts Dami. The third reed switch, parallel to the Start button, is the closing contact of the first reed relay, and the control unit is made in the form of serially connected current sensors and a pulse shaper, while the inputs of the current sensors are the inputs of the control unit, and the outputs of the pulse shaper