SU925220A1 - Device for differential-phase motor protection - Google Patents

Abstract

1. DEVICE FOR DIFFERENTIAL-PHASE ELECTRIC MOTOR PROTECTION, containing current transformers for each phase on the side of the power inputs and zero outputs, the secondary of which are connected to the inputs of the current converter unit, the outputs of which are. to the input of the phase-equalizing unit, the output of the latter is connected to the input of the executive body, and the output of the executive body is included in the motor disconnecting circuit, characterized in that, in order to ensure self-monitoring of health and increase reliability, two additional current transducer blocks are included, the inputs of which are included in series with the inputs of the aforementioned current transducer block, and the outputs are connected to the inputs of two additionally introduced phase-matching blocks, the outputs of each phase-matching The unit is connected to the input of one of the three newly introduced self-monitoring units of operability, and the outputs of the latter are connected to the input of the executive body. 2. Device POP.1, DIFFERENT in that each of the self-monitoring of serviceability blocks contains a three-position polarized relay, the working winding of which is connected to the output of the corresponding phase-matching unit, the end of the working winding and the beginning of the brake winding to the minus of the power source, the end of the brake winding to the left contact. a three-position polarized relay, the measur of which through a resistor and signal signal to the positive power source, the right contact through the diode to the input of the actuator and to the input of the power supply About% self-serviceability. 3. The device in accordance with claim 1, ex (the control unit itself; it contains three precision relays, one winding terminal of each of them is connected through the opening of the relay contacts. The motor switch is turned off to the positive power source, and the second output of each intermediate relay connected through one of the three additional thyristors to the minus of the power source; the control output of each thyristor is connected through a resistor to the output of the health control unit, the serially connected contacts of the first and The second intermediate relay as well as the second and third intermediate relay are connected to the tripping circuit of the motor switch; moreover, a diode is connected between the connection point of the first and second intermediate relay and the connection point of the second and third intermediate relay.

Description

The invention relates to the field of electrical engineering, namely, to the technique of relay protection and can be used as a differential phase protection of an electric motor against phase-to-phase faults. The devices of differential-phase protection of electric motors are known, which contain current transformers for each phase on the input side and zero outputs, to which the units for comparing the electrical quantities in phase are connected, and the latter are connected to the actuator l. The closest in technical solution to the proposed device is differential phase protection of an electric motor containing current transformers for each phase from the side of power supply inputs and zero leads, the secondary windings of which are connected to the inputs of the unit eobrazovateley current outputs of which are inputs to fazosravnivayuschego unit outputs the latter - to the input of executive enforcement agencies and executive yield - a motor-off circuit 2j. Its disadvantage is the possibility of false positives and failure in the event of the failure of one of its elements, as well as the inability to control these failures. The purpose of the invention is to ensure self-monitoring of operability and increased reliability. This is achieved in that the device for differential-phase protection of an electric motor additionally introduces two current transducer blocks, the inputs of which are connected in series with the inputs of the above-mentioned current transducer block, and the outputs are connected to the inputs of two additionally introduced phase-equalizing blocks of the the input of one of the three newly introduced self-monitoring blocks of health, and the outputs of the latter — to the entrance of the executive body, each of which blocks self-checking and rectified comprises three position polarized relay operating coil whose beginning under respective keys to the output unit fazosravnivayuschego end Started whose winding and brake winding start j g / mnusu power source, a brake winding end - to the left three-position contact polarized relays. Measles through a resistor and a signal lamp to the power supply source, the first contact through the diode to the input of the actuator and to the input of the self-checking unit of serviceability, the actuator containing three intermediate relays, one winding terminal ka; the opening contacts of the position relay are turned off by the motor switch to the power supply plus, and the second output of each intermediate relay is connected via one of three additional thyristors to the power supply minus controlling the output of each The thyristor is connected through a resistor to the output of the self-monitoring unit, the serially connected contacts of the first and second intermediate relays, and the second and third intermediate relays are connected to the opening circuit of the motor switch, and between the point of connection of the contacts of the first and second intermediate relays The third intermediate relay is connected diode. Figure 1 shows the scheme of the proposed device, on the FKG, 2 - cxei-tb: blocks of current transducers, phase shifters -1 and 1111 of their blocks and blocks of self-control for operability; on - scheme of the executive unit. The device contains an electric motor 1, current transformers 2-7, conclusions 8-19 secondary windings of current transformers, inputs 20-31 of current transducer blocks, blocks of 32 current transducers, outputs 33-44 blocks of current transducers connected to the same-name inputs of phase-equalizing blocks 45, outputs 46 phase-matching blocks, inputs 47 blocks self-monitoring of health, blocks 48 self-checking of health, outputs 49 of the block self-monitoring of health, diodes 50-51, inputs 52 of the actuating block, the executive block 53 acting on the shutdown of electrodes igatel. CxeNibi blocks. 32 current transducers, phase-equalizing units 45 and self-monitoring units 48 are operable, contain transreactors 54-59, resistors 60-77, diodes 78-95, resistors 96-101, two-winding three-position polarized relays 102, working windings of each polarized relay 103, brake the winding of each polarized relay 104, the left contact 105 and the right contact 106 of each polarized relay, resistors 107, signal 108. The circuit of the executive unit 53 contains the opening contacts 109 of the position relay The motor is turned off, closed with the field turned on the output of an electric motor switch, output intermediate relays 110-112 with their contacts 113-115 respectively, Thyristors 116-118, resistors 119-121, diode 122.

The device works as follows.

In the normal mode of operation of the electric motor with the flow of current siarpysKH 3g and Rear, coinciding in phase in half a period of half a year. At half a wave, for example, current C, diodes 78 and 80 of each of blocks 45 are closed, current flows through the chains 100, 79, 61 and 101, 81, 65, and diodes 79 and 81 are open. The windings 103 of the caddy relay 102 are shunted through pairwise open diodes 78, 80 or 79, 81 and the relay 102 do not operate (the resistance of resistors 60–77 is D.1 times less than the resistance of the winding of relay 102).

For interfax; Fas: -: s: short circuits inside the motor, the current on the zero side changes the phase compared to the input current. If these currents are in antiphase, then with a positive half-wave of the current, such as phase C, in each phase-matching unit diodes 78 and 81 will be closed, and diodes 79 and 80 will be open. Chains 100, 79 ,. 61 and 100, VO, 64 will flow current and I-run diodes 94, but since diodes 78 and 81 are closed, current flows through circuit 101, 95, 46, 47, 103.

Relay 102 of each block 48 is triggered, closes its right contacts 106 and through diode 50 becomes Cc1 mop, and through diode 51 supplies plus to the control outputs of the thyristors 116-118, intermediate relays 110-112 work and their contacts 113-115 create a circuit on motor disconnection

In case of a three-phase short circuit at the terminals of the electrode-kgatel at the start, when the engine is not yet rotated, the hot current from the side of the cool-off leads of the electric jigsaw, goes to transreactors 35, 57, 59 of block 32 and feed through the.,; 68, 69; 74, 75 voltage with reverse sign. about/; .Greenreactors 54, 56, 58 and actuation occurs in a similar manner,

If one of the elements of the current or phase-current block block is damaged, the block is triggered

health self-monitoring unit connected to the output of the faulty unit. The tripping protection of the motor is not triggered}} 1Т, since for the actuation of the execution unit it is necessary to operate at least two phase-matched b EYES,

For example, if the fault type diode 78 fails, the output 33 of the unit 32, which is simultaneously the output of the secondary winding of the transreactor 54, is directly connected to the positive half of the current through the diode 95 to the output 46 of the block 45. In this case, the winding 103 of the self-monitoring unit 4B is flowed by current , the relay 102 triggers and closes the right contact 106 and through diode 50 it becomes self-grip, and through diode 51 it supplies a plus to the control output 119 of the thyristor 116 of the executive unit 53. At this, the signal lamp 108 lights up, indicating a false operation. e unit 45, execution unit 53 is not activated.

Similarly, the detection of any of the faults of blocks 32 or 45, causing the appearance of a plus at the output 46.

When a negative polarity signal appears at the output 46, which corresponds, for example, F; ep, the breakdown of diode 95, relay 102. triggers, closes its left contact 105 and with the help of winding 104 it becomes on CciMO pickup, and lamp 108 signals a faulty condition research unit 45,32

Relay 102 is returned by removing the faulty unit 48, which is structurally combined with unit 45, or by disconnecting the device power supply after disconnecting the damaged electrostatum: gate. It is not removed from the replacement of the faulty unit

In case of failures of sidewalls 32 or 45, the protection remains operable.

Thus, the proposed device has a higher reliability than similar ones, as well as a self-checking of serviceability, simple maintenance, and is realized on the elements produced by industry.

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Claims (3)

1. DEVICE FOR DIFFERENTIAL-PHASE PROTECTION OF ELECTRIC MOTOR, containing current transformers for each phase from the side of power inputs and yule outputs, the secondary windings of which are connected to the inputs of the block of current converters, the outputs of which are to the inputs of the phase-comparing block, the output of the latter being connected to the input of the actuator and the output of the executive body is included in the motor shutdown circuit, characterized in that, in order to ensure self-monitoring of serviceability and increase reliability, two additional and a block of current converters, the inputs of which are connected in series with the inputs of the aforementioned block of converters, current, and the outputs are connected to the inputs of two additionally introduced phaeo-comparing units, the outputs of each phase-comparing unit are connected to the input of one of the three newly introduced self-monitoring units, and the outputs of the latter to the input executive body. 2. Device pop. 1, characterized in that each of the self-serviceability control units contains a three-pole polarized relay, the beginning of the working winding of which is connected to the output of the corresponding phase-comparing unit, the end of the working winding and the beginning of the brake winding are negative of the power source, the end of the brake windings - the left kontaktu.trehpozitsionnogo polarized relay, the armature of which via a resistor and the signal lamp to the positive power source, the right contact through diode - to the input of the executive authority and to the input _of a block self-monitoring of serviceability. $ 3. The device according to claim 1, the condition is that the executive body ^ contains three intermediate * relays, one terminal of the winding of each of them is connected through the disconnecting contacts of the position relay. the motor circuit breaker to the plus of the power source, and the second output of each intermediate relay is connected through one of three additional thyristors to the minus of the power source, the control output of each thyristor is connected via a resistor to the output of the self-monitoring unit, the contacts of the first second intermediate relay, and the second intermediate i.tretego relay trip circuit connected to the motor circuit breaker, the connection point between the first contact and the second intermediate relay and the junction point of the second and third intermediate relay connected diode. I