SU1356113A2 - Apparatus for heat protection of electric motor - Google Patents

Abstract

The invention relates to electrical engineering and is intended to protect against overheating of electrical installations of alternating current. The purpose of the invention is to expand the functionality of the device by indicating incomplete operation modes. An increase in the temperature of the windings 1 of the electric motor leads to the closing of all the triacs 3, the current flows through the shunt RC chains 4. At the same time, the voltage drop across the shunts 5. is insufficient for opening the optocouplers 8 and the phase indicators 9 are off. The trigger voltage of the threshold element 16 is selected less than the voltage drop across the shunts 5, the signal of the logical unit is saved at the output of the threshold element, the logical zero signal appears at the output of the 4-НЕ 17 signal, which leads to an indication. . torus 18 triggered protection. In the event of a break in one of the windings 1 of the electric motor, there is no voltage drop on the corresponding shunt sufficient to open the optocoupler 8 and turn on the phase indicator 9. 1 il. c (L 00 JV O5 00 1H

Description

The invention relates to thermal protection of electrical installations of alternating current, can be used for thermal protection of an electric motor and is an improvement of the known device according to the author. No. 127406

The purpose of the invention is to expand the functional capabilities of the device by indicating non-phase modes of operation.

The drawing shows a schematic diagram of the proposed device.

The device for thermal protection of an electric motor, the windings 1 of which are connected to the phases of the supply network 2, consists of triacs 3, shunt RC circuits 4, shunts 5, bridge rectifiers 6, resistors 7, optocouplers 8. and indicators 9 phases in each phase of the posistor 10 current limiting

a resistor 11, an RC flip-flop 12, a transistor switch 13, a diode buffer stage 14, a three-phase single-phase rectifier 15, a threshold element 16, a logic element 4I-NE 17, a protection actuation indicator 18.

The device works as follows.

When power is applied to the protected motor, through its windings 1, an operating current begins to flow, creating a voltage drop across the shunts 5. This voltage is rectified. bridge rectifiers 6 and, entering the input of optocouplers 8, opens them. In this case, all phase indicators 9 are turned on, which indicates the normal operation of the motor

An increase in the temperature of the windings 1 of the electric motor leads to the closing of all the triacs 3 and the current of the windings 1 flows through the shunting RC - chains 4, the parameters of which determine the magnitude of this current. At the same time, the voltage drop across shunts 5 is insufficient to open the optocouplers 8 and the phase indicators 9 find

c in the off state. But, for example, gQ on with the phase indicator connected to the triggering of the threshold element corresponding to the three inputs of lot 16 is chosen less than that of the pylinic element 4ID, the output codentation of voltage on the shunts 5, and at the output of the threshold element 16 the signal corresponds to level 1, and since the optocouplers 8 are in the closed state, four 1 are fed to the input of the logic element 4I-NOT 17, and the output

The signal is O, which leads to the inclusion of a protection indicator 18. In case of other damages, the output of the logic element 4И-НЕ 17 is present in signal 1 and the protection trigger indicator 18 will be turned off.

In the event of a break in one of the windings, 1 electric motor on the corresponding shunt does not create a voltage drop sufficient to open the optocoupler 8 and turn on the phase indicator 9. Similarly, the scheme works with breaks in other phases.

When the engine is turned off, which is equivalent to the case of three phases being cut off simultaneously, all indicators are in the off state.

Thus, the use of this device allows you to expand its functionality by indicating the normal operation of the electric motor in the types of damage that has occurred: thermal protection tripping, phase breaks.

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formula of invention

Device for thermal protection of an electric motor according to auth. № 1274061, exc. its reason is that, in order to expand the functional capabilities of the device by indicating non-full-phase modes

35 works, in addition, shunts, bridge rectifiers, resistors, optocouplers and indicators are introduced in each of the three phases of the mains supply, the threshold element, the logical element 4И-НЕ,

40 protection actuation indicator and power source, and in parallel to the shunt in each phase, connected in series to the winding of the electric motor, is connected the input of the bridge terminal 45, to the output of which through the resistor is connected the input of the optocoupler, whose output is connected in series with the phase indicator to the power source, the connection point the output is connected in series with the indicator of the protection operation to the power source, the output of the threshold element, the input to the fourth input of the logic element 4Y-NOT orogo connected to the output of the bridge rectifier 1 audio phases.

Claims (1)

Formula I Device No. 1274061 to ensure that the device’s capabilities are available by indicating 35 non-phase modes of operation, shunts, bridge rectifiers, resistors, optocouplers and indicators in each of the three phases of the supply network, a threshold element, a 4I-NOT logic element, a protection operation indicator are additionally introduced into it. and a power source, and parallel to the shunt in each phase, connected in series with the motor winding, the input of the bridge rectifier is connected, the output of which through the resistor is connected to the input of the optocoupler, the output of which is connected is connected in series with the phase indicator to the power source, the opto5θ output connection point with the phase indicator is connected to the corresponding of the three inputs of the 4I-NOT logic element, the output of which is connected in series with the protection operation indicator to the power source, and the fourth input of the 4Y-NOT logic element is connected output of a threshold element * whose input is connected to the output of a bridge rectifier of one cc phase.