SU1123076A1 - Device for protecting three-phase motor - Google Patents

Abstract

1. A DEVICE FOR PROTECTING A THREE-PHASE ELECTRIC MOTOR. Contains .e first, second and third blocks with magnetically controlled elements arranged in the magnetic field of the conductor of each phase of the motor on the supply side; fourth, fifth and sixth blocks with magnetically controlled1 .1 and elements, located in the magnetic field of the conductor of each phase of the electric motor, respectively, from the side of the neutral, the seventh block with magnetically controlled elements, located in the magnetic field of the conductor of one of the phases of the electric motor with one hundred They are powered, the outputs of the first and fourth, second ip of the third and sixth blocks with magnetic elements are connected respectively to the inputs of the first, second and third elements AND, the outputs of which are connected to the authority, connected to the output of the seventh unit with magnetically controlled elements, characterized in that in order to extend the functionality by protecting the motor from winding short circuits and phase failure, a fourth, fifth is additionally introduced into it. the sixth, seventh, eighth and ninth elements And, the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth and eleventh elements of the TIME, first, second and third elements of the MEMORY, the element BAN, at In this case, the outputs of the first, second and third elements I are connected via the first, second and third elements of TIME, respectively, to the first element of the MEMORY, the output of which is connected to the reacting organ, and the output of the first block with the magnetogravable elements is connected to ONE of the fourth, fifth, and seventh And elements, the output of the second block with magnetically controlled I elements connected to one of the inputs of the fifth, sixth and ninth elements And, the output of the third block with magnetic elements connected to one of the inputs of the fourth, sixth and eighth elements And, the output of the fourth block with the magnetically controlled elements are connected to one of the inputs of the eighth element I, the output of the nth block with the magnetically controlled elements is connected to one of the inputs of the seventh element I, the output of the sixth block with the magnetic control elements connected It is connected to one of the inputs of the ninth element I, and the outputs of the fourth, fifth and sixth elements of AND are connected via the fourth fifth and sixth elements of the TIME respectively to the second element of MEMORY, the output of the seventh, eighth and ninth elements of I are connected through the seventh, eighth and the ninth elements of the TIME respectively to the third element of the MEMORY, the output of the second element of the MEMORY through the series-connected elements of the PROHIBITION and the tenth element of the TIME connected to the executive body, the output of the third element of the MEMORY inen with blocking input

Description

element BAN and eleventh element TIME, the output of which is connected to the executive body.

2, Device POP.1. REPLACE that the first, second, third, fourth and fifth, and sixth blocks with magnetically controlled

the elements are made in the form of a reed switch with a winding connected to a source of operating current, with the polarities of the windings of the first, second and third blocks opposite to the polarities of the windings of the fourth, fifth and sixth blocks.

The invention relates to electrical engineering, in particular, to a relay protection technique, and can be used as protection of electric motors against interfacial and winding short circuits, as well as protection against phase failure without the use of gok transformers, iiSBecTHO device for maximum current protection of electric bodies of bodies against short of short circuits containing a reed switch and an actuator, however, this device has a low sensitivity to short circuits inside an electric motor. The device closest to the invention is motor protection, which contains blocks with magnetocontrollable elements located in the magnetic field of the conductors of the phases of the motor, AND logic elements, each of which is connected to the outputs of two blocks of the corresponding phase, and an executive body to which the output from the 2 j blocks is connected. However, the device is not aware of soe, it does not react to the end-turn of the electric motor and to an open phase. The purpose of the invention is to expand the functionality of the device by turning off the motor during winding and phase failure. The goal is achieved by those. In the device for protection of a three-phase electric motor, containing the first, second and third blocks of magnetically controlled elements located in the magnetic field of the conductor of each of the phases of the electrode player on the supply side, the fourth, fifth and sixth blocks with magnetically controlled elements, located in the magnetic field of the talker of each of the phases of the electric motor, respectively, on the neutral side of the seventh unit with magnetic elements, located in the magnetic field of the conductor The second phase of the motor on the supply side, the outputs of the first and fourth, second and fifth, third and sixth blocks with magnetically controlled elements are connected respectively to the inputs of the first, second and third elements, the outputs of which are connected to the actuator, To which the output of the seventh block with magnetically controlled elements is also connected, the fourth, fifth, sixth, seventh, eighth and ninth elements are additionally introduced. And the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth and one The eleventh elements are TIME, the first, second and third elements are MEMORY, the element is BANNED, while the outputs of the first, second and third elements are AND connected through the first, second and third elements of TIME respectively to the first element P.MAMY, the output of which is connected to the reacting authority, moreover, the output of the first block with magkito-guided elements is connected to one of the inputs of the fourth, IRO and Seventh And elements, the output of the second block with magnetic-controlled elements is connected to the code one from the input I tgr, sixth and ninth And elements, The output of the third block with magnetoelastic elements is connected to one of the inputs of the fourth, sixth and eighth elements, And the output of the quarter A block with max-controlled elements is connected to one of the inputs of the eighth element And, the output of the fifth block with magnetic control unit .1 and elements connected to one of the inputs of the seventh element And, the output of a six-unit with magnetic-controlled elements is connected to one of the inputs of the ninth element And, and the outputs of the fourth, fifth and sixth elements of And are connected through the fourth, fifth and sixth elements TIME respectively to the second element MEMORY, the outputs of the seventh, eighth and ninth elements AND connected through the seventh, eighth

and the ninth elements of the TIME respectively to the third element of the MEMORY, and the output of the second element of the MEMORY through the series-connected element BAN and. tenth element. TIME is connected to the executive body, the output of the third element of the PLGNT is connected to the blocking input of the BANNER element and one-tenth element of the TIME, the output of which is connected to the executive body, the first, second, third, fourth, fifth and sixth blocks with the magnetic control elements EPOL-, neng in the form of a reed switch with a winding connected to the source of operational hok, and the polarity of the windings of the first, second and third blocks are opposite to the polarity of the winding: the fourth, fifth and sixth blocks o

"And figure 1 shows the functional diagram of the device; FIG. 2 illustrates the execution of blocks with magnetic elements; FIG.

The proposed device (Fig. 1) contains blocks 1-7 with magnetically electrically fusible elements located in the magnetic field of the conductors so that the first and fourth, second and fifth, are. the third and sixth blocks form a signal at the output to different semi-diversified alternating current feeding the electric motor 8. At that, the blocks 1,2,3 and 7 are installed in the breaker outputs of the switch, 4-6 blocks from the zero outputs of the electric motor 8,

The first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth logical elements of AND 9-17, respectively, are connected to the outputs of blocks 1-6.

The output of block 1 is connected to one of the inputs of the elements 9,12,13 and. 15; output block; and 2 connected to one of the inputs of elements 10, .13,14 and 17; the output of block 3 is connected to one of the inputs of elements 11,12,14 and 16; the output of block 4 is connected to one of the inputs of elements 9 and 16; the output of block 5 is connected to one of the outlets of elements 10 and 15; the output of block b is connected to one input of elements 11 and 17.

The first, second, third, fourth, fifth, sixth, seventh, and ninth elements of TIME 18-26, respectively, are connected to the outputs of the AND elements.

Block 7 and the tenth and eleventh elements BPEMJR 27 and 28 are connected to the executive body 29, which turns off the switch 30, the first element MEMORY 31 is connected to the outputs of the elements TIME 18-20 and the second element MEMORY 32 is connected to the outputs elements TIME 24-26 the third element MEMORY 33 is connected, with the outputs

elements 32 and 33 to the element BAN 34.

Block 7 is executed in B1: -. A normal reed switch and performs the functions of protection against three-phase r.3. at the moment of switching on the switch, when the engine is running, the hoist is still not rotating. The tripping current of the heckron (i.e., the bus current at which it is triggered) is selected to 4HO in the same way as in a conventional maximum current protection.

Blocks 1 are made in the form of reed switches 35 and 3.6 with windings 37 and 38, respectively. With

5 3VOM polarity of the direct current supplied to the winding 37 of the reed switches 35, on which blocks 1-3 are executed, should be opposite to the polarity of the current supplied to the winding 38 of each of the reed switches 36,

0 on which blocks 4-6 are executed. In order for the reed switches to give a signal only in one half period of alternating current, a constant current is applied to their windings, sufficient for

5 srabhtyvany. Then the reed switch disappears only in one half-wave of alternating current for the time of exceeding the amplitude of alternating current by the magnitude of the operation current.

0

Dropout is used to emit a signal,.

To improve speed and reliability, the device can be supplemented with the exact same circuitry as

5 in FIG. 1, the connection of the -I elements and the complementary circuit produce exactly the same / but to the outputs shown by a dotted line (FIG. 1). Each block is executed with at least two

0 magnetically controlled elements. When performing a block on two reed switches, the polarity kx of the control windings is opposite. In this case, the device makes a comparison of the phases of the currents in both half-waves of the transducer

5 current.

Elements 21-23 are set to a time equal to the time that the signals from the corresponding blocks coincide when the phases of the currents of the electric motor bodies shift by 60-70 °. On elements 24-26 with a shift of 150-160, on elements 18-20 - c. 80-90. Elements 18-26 compares the coincidence times of positive or negative

5 half-waves of current.

The device works as follows

In load or motor start mode, the angle between the current vectors

0 of its phases is equal to 120, and there is no signal at the outputs of elements 18-26, since the coincidence time of signals at the inputs of the elements to which they are connected is less than

5 on them. In case of interfunctional short circuit (short circuit), the nitri of the electric motor or the connecting cable, the phase in the damaged phase from the side of the neutral leads changes to opposite, by the time of coincidence of the signals from the blocks with the magnetically controlled elements of this phase exceeds the 143-20, and a signal appears at the input of the first element MEMORY 31, which is stored for the time of the indicated signals. The actuator 29 switches off the switch 30. With a 9-YET short circuit inside the motor, the phase shift between the currents of the damaged and one of the intact phases becomes less than 60 °. The coincidence time of the signals from the blocks of these phases exceeds that set on elements 21–23. And a signal appears at the input of BAN 34. There is no signal at its blocking input, since none of the elements 24–26 is lost. After a time delay exceeding that established on elements 24-26, the element TIME 27 sends a signal to the executive body. When one of the motor phases is broken, the currents of the other two are in antiphase. The coincidence times of the signals coming from blocks 1 and 5 or 2 and b, or 3 and 4 to elements 15-17, respectively, exceed the time set on elements 24-26, and a signal appears at the output of element MEMORY 33 (element 33 remembers the signal for mismatch., as elements 31 to 32). After a time delay (0.5-1 s) element 22 sends a signal to the isp. body body. The time delay is set for the purpose of failure of protection when the asymmetrical short circuit external to the motor, when the currents are in two damaged phases at the first moment of the short circuit. close to antiphase. Since the angle between the current of the damaged and intact phases with this short-circuit. may be small, perhaps the appearance of the signal at the output of the elements 21-23. But the excessive protection operation is blocked by the signal received from element 33 to the inverse input of the BAN 34 element. With a three-phase short-circuit. when the motor is turned on (when the motor is still. does not rotate) the magnetic control element of block 7 is activated and sends a signal to the actuator. Thus, the proposed device protects the electric motor from phase to phase and short circuits and from phase failure, does not require complex equipment, and be used to protect electric motors of different power.

g

 "

+37 ff .5,6

Claims (2)

1. DEVICE FOR PROTECTING A THREE-PHASE ELECTRIC MOTOR, containing the first, second, and third blocks with magnetically controlled elements located in the magnetic field of the current path of each of the phases of the electric motor on the supply side, the fourth, fifth and sixth blocks with magnetically controlled elements located in the magnetic field of the current lead of each phase the motor, respectively, from the neutral side, the seventh block with magnetically controlled elements, · located in the magnetic field of the current path of one of the phases of the motor from the side of the power supply the outputs of the first and fourth, second and fifth, third and sixth blocks with magnetically controlled elements are connected respectively to the inputs of the first, second and third elements And, the outputs of which are connected to the executive body, to which the output of the seventh block with magnetically controlled elements is also connected, characterized in that in order to expand the functionality by protecting the motor from bit circuits and phase failure, it is additionally introduced the fourth, fifth, sixth, seventh, eighth and ninth th elements AND, first, second, third, fourth, fifth, sixth, seventh / eighth, ninth, tenth and eleventh elements TIME, first, second and third elements MEMORY, power outputs first-time PROHIBIT, while the th, second and third elements AND are connected through the first, second and third TIME elements, respectively, to the first MEMORY element, the output of which is connected to the reacting organ, the output of the first block with magnetically controlled electric connected to one of the inputs of the fourth, fifth and seventh elements And, the output of the second block with magnetically controlled elements is connected to one of the inputs of the fifth, sixth and ninth elements And the output of the third block with magnetically connected elements is connected to one of the inputs of the fourth, sixth and eighth And elements, the output of the fourth block with magnetically controlled elements is connected to one of the inputs of the eighth element And, the output of the fifth block with magnetically controlled elements is connected: to one of the inputs of the seventh element And, output One of the sixth block with magnetic control. with B 1123076 The connected elements are connected to one of the inputs of the ninth element AND, and the outputs of the fourth, fifth and sixth elements AND are connected through the fourth, fifth and sixth elements TIME, respectively, to the second element MEMORY, the outputs of the seventh, eighth and ninth elements AND are connected through the seventh, eighth and the ninth elements TIME respectively to the third element MEMORY, and the output of the second element MEMORY through series-connected elements BAN and the tenth element TIME is connected to the executive body, the output of the third element MEMORY is connected to a blocking input. the element BAN and the eleventh element TIME, the output of which is connected to the executive body. 2. DEVICE ARE 1, characterized in that the first, second, third, fourth, fifth, and sixth blocks with magnetically controlled elements are made in the form of a reed switch with a winding connected to an operating current source, and the polarities of the windings of the first, second and third blocks are opposite to the polarity windings of the fourth, fifth and sixth blocks.