CN2133970Y

CN2133970Y - Phase interruption and overload protector for power transformer and motor

Info

Publication number: CN2133970Y
Application number: CN 92209983
Authority: CN
Inventors: 李林山; 李林成
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-05-23
Filing date: 1992-05-23
Publication date: 1993-05-19
Anticipated expiration: 2002-05-23

Abstract

The utility model relates to a phase interruption and overload protector for power transformer and motor, which has the advantages of low cost, high reliability, simple structure and convenient operation. The utility model is composed of a protective circuit of electric current sampling and phase interruption, a protective circuit of phase sampling and phase interruption, a protective circuit of power voltage transformation and overload, a protective circuit of motor overload, a power supply circuit and an output circuit.

Description

Phase interruption and overload protector for power transformer and motor

The utility model relates to a kind of power transformer motor overload of loss of phase protector.

Existing power transformer, motor owing to lack safety precautions such as the phase failure, overload, burn in the use easily, have an accident.

It is low that the purpose of this utility model provides a kind of cost, dependable performance, simple structure, power transformer easy to use, the motor phase failure, overload protective device.

Advantage of the present utility model is: 1. the utility model adopts multiple phase failure detection means, guarantees that open phase protection safety is timely.2. the utility model adopts multiple overload detection means, guarantees that overload protection is safe and reliable.3. the utility model circuit has modular construction, is convenient to machine debugging.4. the utility model circuit structure is simple, and cost is low, is convenient to popularize.

Fig. 1 is the utility model schematic block circuit diagram.

Fig. 2 a, b, c, d, e are the utility model circuit theory exploded views.

Fig. 3 is Fig. 2 a, b, c, d, e location diagram.

Referring to Fig. 1: the utility model is connected to form by current sampling open-phase protection circuit, phase-samplomh open-phase protection circuit, power transformer overload protecting circuit, motor overload protection circuit, power circuit and output circuit. The current sampling open-phase protection circuit, annular AC transducer LBA1, LBA2, LBA3 are enclosed within respectively in A, B, the C three-phase circuit in the described current sampling open-phase protection circuit, the Same Name of Ends of LBA1, LBA2, LBA3 links to each other with triode BGA7, BGA8, BGA9 base stage with resistance R A1, RA2, RA3 by diode BGA1, BGA2, BGA3 respectively, and the colelctor electrode of triode BGA7 links to each other with in-phase end with the end of oppisite phase of operational amplifier ICA respectively through resistance R A6, RA7; The phase-samplomh open-phase protection circuit, phase transformer BB1～BB3 is elementary in the described phase-samplomh open-phase protection circuit is connected on respectively in the ABC three-phase circuit, secondary Same Name of Ends is respectively through potentiometer RWB1～RWB3, diode BGB1～BGB3 links to each other with resistance R B5 one end, and the resistance R B5 other end links to each other with the end of oppisite phase of the voltage comparator that is made up of ICB; The power transformer overload protecting circuit; described power transformer overload protecting circuit comprises the identical circuit of three covers; respectively by annular AC transducer LBCi(i=1～3) be socketed on A, B, the C three-phase power line transformer LBCi(i=1～3) end and diode BGCi(i=1～3) Link to each other diode BGCi(i=1～3) the secondary identical comparator circuit of four line structures that is connected with, every road comparator includes a slice operational amplifier ICCi(i=1～12); The motor overload protection circuit, AC transducer LBD is enclosed within A, B in the described motor overload protection circuit, the C three phase mains is arbitrary goes up mutually, a secondary end is through potentiometer RWE1, diode BGE1, resistance R E3, RE4 series arm and the comparator in-phase end that is made up of operational amplifier 1CE link to each other; Operational amplifier ICA, the ICB of described each holding circuit, ICi(i=1～12), the ICE output links to each other with output circuit base resistance RF1 one end respectively, and the colelctor electrode of triode BGF1 is connected with relay J and diode BGF2 parallel branch. It also comprises a power circuit the utility model, voltage transformer BE primary coil two ends are connected on respectively power transformer or motor magnetic switch output, secondary tap L2 links to each other with the bridge rectifier input, the output of bridge rectifier and the circuit of three-terminal voltage-stabilizing integrated IC8, the IC9 that are connected in parallel, diode BGG1 input terminal links to each other, secondary tap L3 links to each other with the input of another bridge rectifier, the output of bridge rectifier and the circuit of three-terminal voltage-stabilizing integrated IC10 that is connected in parallel, diode BGG2 input links to each other. In the current sampling open-phase protection circuit; wherein 12 cover comparator circuits are to construct like this; operational amplifier ICCi(i=1; 12) in-phase input end is connected to resistance R Ci(i=1; 12); press button QAi(i=1,12) the T shape networking that and QBi(i=1,12) connects; described press button QAi(i=1; 12) be connected in parallel to resistance R QAi(i=1,12), described press button is connected in parallel to resistance R QBi(i=1; 12; described amplifier ICCi(i=1,12) output is connected with diode BGOi(i=1,12).

Referring to Fig. 2 a, it is the utility model current sampling open-phase protection circuit schematic diagram. LBA1, LBA2, LBA3 are annular AC transducers among the figure, are enclosed within respectively in low-pressure end A, B, the C three-phase circuit of power transformer, or go in the motor three phase mains loop. When having electric current to pass through in the three-phase power line; because electromagnetic induction makes AC converter LBA1～LBA3 coil two ends will produce induced electromotive force; behind diode BGA1～BGA3 and capacitor C A1～CA3 rectifying and wave-filtering, produce d. c. voltage signal; through being added in respectively after resistance R A1～RA3 current limliting between the base stage and emitter stage of transistor BGA7～BGA9; BGA4～BGA6 shields; RA4 is the negative feedback resistor of BGA4～BGA9, makes them be forward bias. When power transformer low-pressure end A, B, C three-phase, or when having electric current to pass through in the motor three-phase power line, AC transducer LBA1～LBA3 two end-coils are the output AC voltage signal simultaneously, makes three transistor BGA7～BGA9 simultaneously Conducting, at this moment capable of regulating potentiometer RWA1 and RWA2 and resistance R A5, making branch piezoelectric crystal BGA7 colelctor electrode is that the A point obtains 0.25 volt of d. c. voltage signal, this voltage signal is by resistance R A6, RA7 is added to respectively the anti-phase and in-phase input end of computing integrated amplifier ICA, and (RA8 is that computing integrated amplifier negative feedback resistor RA8 and RA6 are divided by and are the multiplication factor of operational amplifier, other operational amplifier effects are identical), operational amplifier output this moment electronegative potential, not conducting of diode BGA10, carrying out pipe BGF1 base voltage is that zero volt is in cut-off state, relay J is as the load of carrying out pipe BGF1, there is not electric current to be in normally off by its normally closed some J1-1, because the suction coil two ends of relay J are serially connected in respectively in the magnetic switch suction coil loop of power transformer or motor and go, its normally closed point also is in normally off, and at this moment power transformer or motor normally move. When power transformer output low-pressure end ABC three-phase or motor three-phase power line wherein have one to open circuit mutually; disconnected phase power line does not just have electric current just not have Voltage-output by the coil two ends of AC converter correspondingly; corresponding transistor also is in cut-off state because forward bias disappears; because three emitter-base bandgap gradings of transistor BGA7～BGA9 and colelctor electrode are connected respectively; wherein any transistor cut-off can both make the A point be in about 9～10 volts of high potentials; this high potential passes through RA6; RA7 adds to the anti-phase and in-phase input end of operational amplifier ICA; operational amplifier is just exported high level and is added in diode BGA10 at this moment; after the BGA10 conducting; after resistance R F1 current limliting; make execution pipe BGF1 be saturation state; its collector current reaches maximum; make and carry out pipe BGF1 load-relay J suction coil generation magnetic field and adhesive; normally closed some J1-1 disconnects simultaneously; cut off the magnetic switch suction coil power supply of power transformer or motor; the magnetic switch normally-closed contact is disconnected; power transformer or motor are just at once out of service, have reached the protection purpose that prevents from burning out because of phase shortage power transformer or motor. Its characteristics: 1. component seldom, cost is low easily to be produced, fault rate is very low. 2. service life is long, and drop-away time is exactly highly sensitive very accurate in 1 second. 3. the scope of application is wide, and this protection is suitable for the electric motor circuit breaking protection of various low-voltage power transformers below 1,000 kilovolt-amperes and 1.5 kilowatts to 200 kilowatts. 4. use and fall wide ranges, approximately three phase mains falls 2.5%, can misoperation.

Referring to Fig. 2 b: be the utility model phase-samplomh open-phase protection circuit schematic diagram.Phase transformer BB1～BB3, elementary being connected on respectively in the power transformer output low-pressure side ABC three-phase circuit, phase transformer BB1～BB3 time level is responded to 6 volts of alternating voltages respectively through adjusting potentiometer RWB1～RWB3 dividing potential drop, through diode BGB1～BGB3 and capacitor C B1～CB6 rectifying and wave-filtering and resistance R B1～RB3, obtain 4 volts of d. c. voltage signals respectively at the B point, because the phase place of power transformer high-pressure side and low-pressure side three-phase respectively differs 120 degree, because of phase transformer BB1～BB3 secondary coil two ends are in parallel, so A point direct voltage is three groups of sums, this voltage signal is a reference voltage through the inverting input that resistance R B5 offers operational amplifier ICB, input preliminary election setting voltage is 10 volts simultaneously, adjusts potentiometer RWB4 and the acquisition of resistance R B4 dividing potential drop by stabilized voltage power supply 7812 outputs after capacitor C B9～CB11 and the filtering of resistance R B1 bridge-type.Operational amplifier ICB is a desirable voltage comparator, the inverting input reference voltage is higher than and preestablishes 3 volts of homophase input voltages, operational amplifier output this moment negative potential, carrying out pipe BGF1 base voltage is that zero volt is in cut-off state, relay J is as the load of carrying out pipe BGF1, there is not electric current to pass through, its normally closed some J1-1 is in normally off, because the suction coil two ends of relay J are serially connected in magnetic switch suction coil one end of power transformer respectively, still have electric current to pass through, magnetic switch is not threaded off, and power transformer normally moves.

When power transformer high-pressure side (elementary) wherein has one to open circuit mutually and lacked a phase place; the corresponding phase line of low-pressure side also lacks a phase place so; also lack a phase place so the device of phase place power transformation simultaneously BB1～BB3 is corresponding; the direct voltage of time utmost point reduces 1/3rd thereupon so; this moment, operational amplifier ICB input promptly was that reference voltage B point also reduces 4 volts; the operational amplifier while, input end was in high potential; cause operational amplifier ICB output high level; make through diode BGB4 conducting and resistance R F1 current limliting and CF1 buffering and to carry out pipe BGF1 and be saturation condition; its collector current reaches maximum; make the suction coil of carrying out pipe BGF1 load-relay J produce magnetic field and adhesive; normally closed some J1-1 disconnects simultaneously; cut off the magnetic switch suction coil power of power transformer; the magnetic switch normally-closed contact is disconnected, reached the purpose of protection transformer and transformer load.

Referring to Fig. 2 c, show the utility model power transformer overload protecting circuit schematic diagram.This circuit comprises the identical circuit of three covers, is socketed in respectively on A, B, the C three-phase power line, and the C point of every cover circuit all connects the similar comparator circuit of four tunnel principles, and the mode with square frame in the accompanying drawing is represented.Be example with the first cover circuit, the first cover comparator circuit below, its operation principle and formation are described.

AC transducer LBC(annular) is enclosed within respectively in the power transformer low-pressure side ABC triple line, when the ABC triple line has electric current to pass through, because electromagnetic induction makes AC transducer LBC1 coil two ends will produce induced electromotive force, through diode BGC1, obtain the d. c. voltage signal that the power transformer rated current is responded at the C point behind capacitor C C1～CC2 rectifying and wave-filtering, by starting button QA1 give delay capacitor CQB1 be flushed to load voltage value send into operational amplifier ICC1 simultaneously input as specified reference voltage and in advance by setting voltage (promptly press Electricity Department rules power transformer promulgated by the ministries or commissions of the Central Government allow super stream multiple accurate permit delay time and setting voltage) as the inverting input reference voltage, this voltage by stabilized voltage power supply 7812 output voltages through RWC1, the RC4 dividing potential drop obtains.Operational amplifier is a desirable voltage comparator, operational amplifier ICC1 output this moment negative level, carrying out the pipe base stage is that zero volt is in cut-off state, relay J does not have electric current to pass through as the load of carrying out pipe BGF1, its normally closed some J1-1 is in normally off, because the suction coil two ends of relay J are serially connected in an end of power transformer magnetic switch suction coil respectively, still have electric current to pass through magnetic switch and do not thread off, power transformer normally moves.

When power transformer surpasses the rated current multiple, the electromotive force of being responded to, through diode BGC1, the d. c. voltage signal behind capacitor C C1, the CC2 rectifying and wave-filtering is given time delay resistance RQB1 and is given delay capacitor CQB1 charging, when arriving charging termination, this stage is the time-delay stipulated time.It promptly is the power transformer magnetic switch action moment.When operational amplifier in-phase input end current potential is higher than inverting input and preestablishes current potential when capacitor C QB1 arrives charging termination; promptly export high level; diode BGO1 conducting makes execution pipe BGF1 be saturation condition through resistance R F1 current limliting and capacitor C F1 buffering; its collector current reaches maximum makes the suction coil of carrying out pipe BGF1 load-relay J produce magnetic field and adhesive; normally closed some J1-1 disconnects simultaneously; cut off power transformer magnetic switch suction coil power, the normally closed point of magnetic switch disconnects the purpose that has reached protection transformer and load.

Referring to Fig. 2 d, show the utility model motor overload protection circuit theory diagrams and power circuit principle figure.

AC transducer LBD(annular) is enclosed within the arbitrary phase line of ABC three phase mains; when electric current passes through; because electromagnetic induction; AC transducer LBD coil two ends will produce induced electromotive force; through potentiometer RWD1, RWD2, RWD3 dividing potential drop; obtain rated direct voltage through diode BGD1, capacitor C D1～CD2 and resistance R E1 and be about 2 vor signals and send into the D point, the other parts circuit is identical with the power transformer overload protecting circuit.Transfer RWD1, RWD2, RWD3 to make the D point obtain 2 volts of left and right sides voltages, can be fit to 5.5 kilowatts to 40 kilowatts overloads.

Voltage transformer BE primary coil two ends are connected on power transformer or motor magnetic switch output respectively; after execution pipe BGF1 is saturated 80 milliamperes of electric inflow places are arranged; long-time so electric inflow place; three terminal regulator 7812 can generate heat; reduce its useful life; be connected on the magnetic switch output; having cut off power supply when magnetic switch suction coil causes the relay J adhesive because of the phase failure or overload disconnects normally closed point; power transformer and motor have not only been protected; and protected the working power of this protector simultaneously; protective tube BX specification is 2A, plays a part to prevent the overload of power supply transformation and the burning ring.Secondary LE2～LE3 is 14 volts, directly sends into three terminal regulator 7812,7912 respectively through the direct voltage of total silicon bridge Q1 and Q2 and capacitor C E1, CE2, CE5, CE6 rectifying and wave-filtering.Here 7812 parallel connections can improve electric current provides enough required power for 3A gives 13 operational amplifiers, makes protector normal in service more reliable.Three terminal regulator 7812 is that IC8, IC9 and 7912 are positive 12 volts and bear 12 volts of IC10 output voltage stabilizing, and CE3, CE4, CE7, CE8 are respectively three terminal regulator IC8, IC9 and IC10 filtering and to the buffering of required power supply, Chong Zu electric charge is made stand-by power supply at ordinary times.BGE1 and BGE2 are connected in three terminal regulator 7812,7912 input and output two ends respectively in parallel.

Fig. 2 e shows the utility model output circuit schematic diagram.The base stage of triode BGF1 links to each other with the negative pole of BGA10, BGB4, BGC2, BGD2 through resistance R F1 among the figure, triode BGF1 collector electrode links to each other with the parallel branch of diode BGF2, relay J, the contact J1-1(figure part omitted of relay J) link to each other with the master control current supply circuit of power transformer or motor.

Claims

1, power transformer motor overload of loss of phase protector is characterized in that it comprises:

The current sampling open-phase protection circuit, annular AC transducer LBA1, LBA2, LBA3 are enclosed within respectively in A, B, the C three-phase circuit in the described current sampling open-phase protection circuit, the end of the same name of LBA1, LBA2, LBA3 links to each other with triode BGA7, BGA8, BGA9 base stage with resistance R A1, RA2, RA3 by diode BGA1, BGA2, BGA3 respectively, and the collector electrode of triode BGA7 links to each other with in-phase end with the end of oppisite phase of operational amplifier ICA respectively through resistance R A6, RA7;

The phase-samplomh open-phase protection circuit, phase transformer BB1～BB3 is elementary in the described phase-samplomh open-phase protection circuit is connected on respectively in the ABC three-phase circuit, secondary end of the same name is respectively through potentiometer RWB1～RWB3, diode BGB1～BGB3 links to each other with resistance R B5 one end, and the resistance R B5 other end links to each other with the end of oppisite phase of the voltage comparator of being made up of ICB;

The power transformer overload protecting circuit, described power transformer overload protecting circuit comprises the identical circuit of three covers, be socketed on A, B, the C three-phase power line by annular AC transducer LBCi (i=1～3) respectively, transformer LBCi (i=1～a 3) end links to each other with diode BGCi (i=1～3), the secondary identical comparator circuit of four line structures that is connected with of diode BGCi (i=1～3), every road comparator includes a slice operational amplifier ICCi (i=1～12);

The motor overload protection circuit, AC transducer LBD is enclosed within A, B in the described motor overload protection circuit, the C three phase mains is arbitrary goes up mutually, a secondary end is through potentiometer RWE1, diode BGE1, resistance R E3, RE4 series arm and the comparator in-phase end of being made up of operational amplifier 1CE link to each other;

Operational amplifier ICA, the ICB of described each protective circuit, ICi (i=1～12), ICE output link to each other with output circuit base resistance RF1 one end respectively, and the collector electrode of triode BGF1 is connected with relay J and diode BGF2 parallel branch.

2; by the described power transformer motor of claim 1 overload of loss of phase protector; it is characterized in that it also comprises a power circuit; voltage transformer BE primary coil two ends are connected on power transformer or motor magnetic switch output respectively; secondary tap L2 links to each other with the bridge rectifier input; the output of bridge rectifier and the circuit of three-terminal voltage-stabilizing integrated IC8 that is connected in parallel; IC9; diode BGG1 input terminal links to each other; secondary tap L3 links to each other with the input of another bridge rectifier; the output of bridge rectifier and the circuit of three-terminal voltage-stabilizing integrated IC10 that is connected in parallel, diode BGG2 input links to each other.

3; by the described phase-samplomh open-phase protection circuit of claim 1; it is characterized in that wherein 12 cover comparator circuits are to construct like this; operational amplifier ICCi(i=1; 12) in-phase input end is connected to resistance R Ci(i=1; 12); push-button switch QAi(i=1,12) and QBi(i=1,12) the T shape networking that connects; described push-button switch QAi(i=1; 12) be connected in parallel to resistance R QAi(i=1,12), described push-button switch is connected in parallel to resistance R QBi(i=1; 12; described amplifier ICCi(i=1,12) output is connected with diode BGOi(i=1,12).