CN2110939U - Multifunctional protection circuit breaker for motor - Google Patents

Abstract

The utility model provides a multifunctional protection circuit breaker for a motor which is used for protective systems of various three-phase asynchronous motors on three-phase three-wire system low-voltage distributing lines and three-phase four-wire low-voltage distributing lines. On the basis of the current leakage protection, the overload protection and the short-circuit protection of a current leakage circuit breaker series DZ15L, the utility model is newly provided with a protection device for instantaneous release of unbalance three-phase current. The multifunctional protection circuit breaker for a motor is characterized in that the multifunctional protection circuit breaker for a motor can make instantaneous action when the three-phase unbalance electric current is >=2 times, which improves the protection performance of the circuit breaker.

Description

Multifunctional protection circuit breaker for motor

The utility model belongs to the threephase asynchronous protective device, particularly a kind of circuit breaker with kinds of protect function.Be suitable for the supporting use of all size motor on three-phase three-wire system and the three-phase four-wire low-voltage distribution line.

Used DZ15L series residual current circuit breaker, its structure mainly is made up of contact system, arc control device, operating mechanism, detection of electrical leakage system, electromagnetic trip system, fluid pressure type electromagnetism overcurrent release (abbreviation overcurrent trip) system and insulation crust.Its performance is that motor is made electric leakage, overload and short-circuit protection.The overcurrent trip characteristic is: thread off in 2 hours when operating current is 1.2 times of release rated current, make overload protection; But threaded off, and made short-circuit protection in 6 times of return time 〉=1 second in 12 times＜0.2 second.The earth leakage protective characteristic is: threaded off in 0.2 second during leakage current 〉=50mA and cut off the electricity supply.

In actual applications, when three-phase current unbalance appears in motor, or even during the serious unbalanced open phase fault of three-phase current, the phase to phase fault electric current is 1.73 times of running current.At this moment, overcurrent trip needs certain hour just can thread off, and long-time running causes sending out of motor heating in winding, even burns.According to probability statistics, motor 76% circuit inter-burnout-ing, 10% electric leakage is burnt, and 10% overload is burnt.Change greatly in the rural area seaonal load, the phase failure is more frequent, only utilizes existing overcurrent trip that open phase fault is done indirect protection, can not protect motor effectively.Therefore, solving phase failure instantaneous trip problem in the motor motion, is the major subjects of protection motor.

For addressing this problem; write by the Shanghai City part-time engineering college in 1977; in electronic technology lecture＜four〉" transistor switching circuit " book that Science Press publishes the 234th page; explained and be entitled as " core transistor formula threephase asynchronous open phase protection "; it is according to after the phase failure occurring; motor three-phase current phase difference becomes 180 ° by 120 °, utilizes the characteristic of magnetization of square magnetic magnetic ferrites material, is wound with two identical windings on this magnetic core.Three-phase power line serial is respectively crossed three magnetic cores, obtains six groups of induced signals, with these signals fellow disciple combination of circuits together.During three characteristics of the middle term current balance type, 120 ° of three-phase current phase differences, synchronization magnetic core coil induced signal can not occur simultaneously; Induced signal will occur simultaneously after the phase failure occurring, can obtain interrupt signal at gate output.Interrupt signal is widened signal pulse through monostable trigger-action circuit again, sends time delay process to and drives inverter at last, is carried out by relay and cuts off the electricity supply.This method can detect the part open phase fault.For example high voltage supply, low-voltage distribution, the equipment electricity consumption phase failure on the three-phase three-wire system power line; The three-phase four-wire system luminous power mixes the equipment electricity consumption phase failure on the modified line road.After the phase failure appearred in these situations, the middle phase failure did not all have return current.But resemble the high voltage supply on the mixed modified line road of three-phase four-wire system luminous power, during the low-voltage distribution phase failure, the middle phase failure all has pair zero line return current, and this electric current is provided through the motor winding by two work.The above-mentioned open phase protection of result just can not detect (its reason is seen below and stated).In recent years, the open phase protection made from regard to useful this principle on the market has with starting equipment to be used, and the product that cooperates with residual current circuit breaker also arranged.No matter the operating circuit interrupt signal of these products is with which kind of mode to handle, or how the DC power supply mode changes, and the method for its input is all the same.

Resemble motor winding inter-turn, phase fault very not serious (equal overcurrent trip rated current 2 times time) in addition, residual current circuit breaker and above-mentioned open phase protection all can not instantaneous trips, cause motor fault to enlarge.Therefore solve the motor winding inter-turn, the phase fault instantaneous trip also is very significant.

Task of the present utility model is that a kind of improved motor protection circuit breaker will be provided, and it has kept overload, short circuit, the creepage protection function of former residual current circuit breaker, has increased the unbalance protection of three-phase current function newly.New function is not only to open phase fault instantaneous trip in the various supply lines, and can be in three-phase imbalance current error 〉=2 times the time to motor winding inter-turn and phase fault instantaneous trip.

Task of the present utility model is finished as follows: the identical overcurrent trip coil of two tools and an electromagnetic trip coil are set in the circuit breaker, and three tripping coils act on respectively on the trip link of operating mechanism.Three phase mains is connected on respectively on three binding posts in upper end, and fixed contact and binding post are integral.Three moving contacts are affected by operating mechanism, engage with corresponding fixed contact or separate, and play the effect of quick break-make power supply.Be connected on the load wiring terminal after one phase moving contact feeder line string overcurrent instrument transformer (newly-increased small-sized core-theaded type current transformer is called for short) and the zero-sequence transformer.In addition the two-phase moving contact draws feeder line and is connected with the head end of overcurrent trip coil, and the tripping coil tail end draws feeder line and went here and there the current transformer of corresponding phase respectively, goes here and there zero-sequence transformer more jointly to the load wiring terminal.Reach the overcurrent trip load current value more than 1,2 times the time when the electric current that flows through circuit breaker connects, release was threaded off in two hours, and electric current is big more, and it is fast more to thread off, and plays overload protective function; When electric current reached more than 6 times, the release instantaneous trip played the short-circuit protection effect; When three-phase imbalance current error 〉=2 times, inducing fault-signal by three current transformers is switched on to solenoid by controlling organization, the magnetictrip action power dump, relatively electric leakage is when reaching 50mA when three-phase electricity is arbitrary, and detection of electrical leakage is by the magnetictrip action power dump.Various like this functions cooperatively interact, and just can effectively protect the motor safe operation.

Here set forth newly-increased three-phase imbalance current detecting basic principle again: three identical current transformers that install additional are the center tapped windings by two identical minor winding coileds, and core material is the ordinary silicon steel disc.During these three current transformers of three-phase equilibrium electric current process, will produce six groups of induction sine wave signals, through unidirectional Rectified alternating current of continuous constant amplitude of gate circuit output; When flowing through the three-phase current unbalance of current transformer, gate circuit output be a unidirectional Rectified alternating current of interrupted constant amplitude or the unidirectional Rectified alternating current of constant amplitude not continuously.The signal of gate circuit output is again through differential circuit, and the unidirectional Rectified alternating current of constant amplitude can not pass through differential circuit, then differential circuit no-output continuously; And interrupted constant amplitude and continuously not the unidirectional Rectified alternating current of constant amplitude can pass through differential circuit, export a spike behind the differential.This spike directly drives inverter because pulse duration is too narrow, and relay will have little time action, so carry out pulse widening through monostable trigger-action circuit again.The pulse signal of having widened is through a time delay process.When pulse signal was discontinuous, delayer did not provide triggering signal; When the pulse signal consecutive hours, delayer provides the conducting of signal triggering controllable silicon, is threaded off by magnetictrip and cuts off the electricity supply, and reaches the purpose that unsymmetrical current is detected.

Circuit work power is obtained by the capacitance decompression halfwave rectifier, does not produce the zero-sequence transformer disturbing magnetic field.DC power supply, three-phase imbalance current detecting and detection of electrical leakage electronic component are contained on the circuit board jointly.This circuit breaker only needs to install three current transformers additional in bottom, former residual current circuit breaker lower end, loads onto circuit board on current transformer, as long as rationally deploy, makes itself and zero-sequence transformer not produce magnetic interference mutually and gets final product.So former residual current circuit breaker structure does not change, simultaneously electronic component is with low cost, three-phase current unbalance instantaneous trip especially, and performance improves, but that cost rises is very few.

Present technique can not only be implemented in the residual current circuit breaker, and can be implemented in the various low pressure starting equipments.Current transformer is owing to be signal transmission device spare, and magnetic field is very weak, and magnetic disturbance is very little.

Below with reference to accompanying drawing utility model is described in further detail.

Fig. 1 is the profile of the motor multifunctional protective circuit breaker concrete structure that the utility model proposes.

Fig. 2 is the circuitry figure of the utility model circuit breaker.

Fig. 3 is M1 among Fig. 2, M2, M3 current transformer winding diagram.

Fig. 4 (1) is current transformer induction voltage waveform figure when being three-phase balance; (2) be G point oscillogram among Fig. 2.

Fig. 5 (1) is a square magnetic ferrite core induced signal oscillogram; Induced signal oscillogram when (2) being three-phase balance; Induced signal oscillogram when (3) being the phase failure.

Current transformer induction voltage waveform figure when Fig. 6 (1) is three-phase current serious uneven (phase failure of C phase); (2) be G point oscillogram among Fig. 2.

Fig. 7 (1) is three-phase imbalance current error current transformer induction voltage waveform figure when equaling 2 times; (2) be G point oscillogram among Fig. 2; (3) be to analyze negative and door when different input voltage, to export situation map.

Table 1 is the corresponding numerical tabular of Fig. 4 (2) waveform.

Table 2 is corresponding numerical tabulars of Fig. 6 (2) waveform.

The concrete structure of this circuit breaker is described below in conjunction with Fig. 1.

This device mainly is made up of contact system 1, arc control device 2, operating mechanism 3, overcurrent release system 4, current transformer 5, zero-sequence transformer 6, electronic component circuit board 7, electromagnetic trip system 8 and insulation crust 9.

The electrical connection and the circuitry operation principle of this device are described in conjunction with Fig. 2 circuitry figure.

Three-phase alternating-current supply is connected on respectively on A phase, B phase, three binding posts of C phase, is connected or the disjunction circuital current by switch HK.A mutually with C mutually feeder line be connected on overcurrent trip coil DT respectively ₁, DT ₂On, tripping coil DT ₁, DT ₂Tail end draws feeder line string overcurrent instrument transformer M respectively ₁, M ₃, went here and there zero-sequence transformer H again to the load wiring terminal of correspondence, middle B phase feeder line passes from electromagnetic trip coil J bottom goes here and there overcurrent instrument transformer M again ₂, zero-sequence transformer H is to the load wiring terminal.

The three-phase imbalance current detection circuit is at first by current transformer M ₁, M ₂, M ₃Respond to three-phase ac signal on the auxiliary winding, these three concrete winding modes of instrument transformer are seen Fig. 3, and they are two center tapped windings that the identical number of turn is formed, winding W ₁, W ₂Form M ₁, W ₃, W ₄Form M ₂, W ₅, W ₆Form M ₃According to W among Fig. 3 ₁-M ₆Ending of the same name is connected on by D ₁-D ₆On the negative AND circuit of forming.W ₁, W ₄, D ₁, D ₂Inspection C phase fault signal, W ₃, W ₆, D ₃, D ₄Inspection A phase fault signal, W ₂, W ₅, D ₅, D ₆Inspection B phase fault signal (its method is with reference to Fig. 6 (1) waveform and the corresponding numerical tabular of table 2).R ₁, R ₂, R ₃Be three gate resistors.D ₇, D ₈, D ₉Form the negative OR circuit of three inputs, can obtain arbitrary phase fault signal at the G point.Negative and the door course of work are with reference to analytical method shown in Fig. 7 (2).Waveform among Fig. 4, Fig. 6 and numerical tabular draw according to Fig. 7 methods analyst.

When three-phase balance, three instrument transformer output waveforms such as Fig. 4 (1), negative and door output voltage numerical value such as table 1, a then negative or door G point obtains the voltage waveform shown in Fig. 4 (2).This waveform is a unidirectional Rectified alternating current corrugating of three continuous constant amplitudes; When the serious uneven promptly middle phase failure of three-phase current did not have return current, current transformer output waveform such as Fig. 6 (1), table 2 were gate circuit input and output voltage numerical value, G point waveform such as Fig. 6 (2).This waveform is a unidirectional Rectified alternating current corrugating of interrupted constant amplitude; When the three-phase imbalance current error equaled 2 times, induction voltage waveform such as Fig. 7 (1) analyzed the G point equally and can obtain waveform shown in Fig. 7 (2), and this waveform is a unidirectional Rectified alternating current corrugating of constant amplitude not continuously.Be not difficult to know by inference, three-phase current unbalance performance one is big mutually, two-phase hour, i.e. delta connection motor winding disconnection fault outside can not detecting because of the electric current variate is little in the motion, just can detect fault-signal when motor starting.

This circuit carries out differential to above-mentioned G point waveform to be handled.According to RC differential circuit operation principle: the saltus step part that the output pulse can be given prominence to input pulse, its output voltage values only is decided by the saltus step amount of input pulse, and is irrelevant with input voltage value.Though above-mentioned G point output is not very big square pulse of saltus step amount or rectangular pulse, but the unidirectional pulsating direct current electrical waveform of the continuous constant amplitude of G point is with constant amplitude and interrupted constant amplitude unidirectional pulse direct current waveform are not compared continuously, the two kinds of waveforms in back have tangible saltus step amount, and preceding a kind of waveform is continuous and constant amplitude, does not possess the impulse hits condition.So this circuit R ₄C ₁, the differential circuit of composition is no signal output when three-phase balance, and signal output is arranged when three-phase current unbalance.Because differential circuit is irrelevant to input voltage value, therefore so the unidirectional direct voltage of continuous constant amplitude that motor starting electric current and different capacity motor current are responded to does not have impulse disturbances to differential circuit, to adapt to multiple power electric motor supporting for a kind of specification current transformer.

The undersuing of saltus step removes to trigger BG after being exported by differential circuit ₁, BG ₂The monostable trigger-action circuit of forming makes the burst pulse of input handle through monostable trigger-action circuit, at BG ₁The positive pulse of certain width of collector electrode output and amplitude.R ₆Be the common resistance of two pipes, play self-supporting bias.Be connected in parallel on the C of input ₂Be anti-tampering usefulness, it plays the high frequency bypass effect.D ₁₀, D ₁₁Be two light-emitting diodes, just often D ₁₁Bright, D during fault ₁₀Bright D ₁₁Whether normally go out, two pipes do not flash the residence with monostable upset, play this device effect of differentiating.

The positive pulse of monostable trigger-action circuit output is through D ₁₂To by R ₇C ₄The time delay process charging of forming.As signal consecutive hours, C ₄Charging voltage raises gradually, diode D when reaching 1.4 volts ₁₃Forward conduction, the G utmost point of triggering controllable silicon SCR, controllable silicon conducting.Electric current from power supply C through diode D ₁₆, electromagnetic trip coil J is to controllable silicon anode A, negative electrode K, end another phase power supply A and go up mutually.The electromagnetic trip coil produces the high-intensity magnetic field adhesive in flakes of will threading off under the function of current, promote connecting rod, the tripping mechanism action power dump.Unidirectional controllable silicon S CR, its reverse DC break down voltage is more than 1200V.D ₁₂Be anti-C ₄In charging process, be provided with to the power supply discharge.Same C ₄R in parallel ₁₁Be to discharge C ₄Residual voltage is provided with, and purpose is consistent each delay time.R ₁₂, C ₅Be the extremely anti-tampering usefulness of SCR control.R ₁₃, R ₁₄, C ₆Be connected in parallel on the controllable silicon anode and cathode, purpose is the pulse voltage that absorbs power supply, and misoperation does not take place the protection controllable silicon.

The earth leakage protective part is by zero-sequence transformer H, diode D ₁₈, C ₈Form signal deteching circuit, arbitrary leakage current relatively reaches 50mA when above in the three-phase, the auxiliary winding L of zero-sequence transformer H ₁Induce signal, through D ₁₈Rectification obtains a positive pulse and goes to trigger the controllable silicon conducting, and the electromagnetic trip coil gets electric dropout and cuts off the electricity supply.L ₁C ₈Resonance has improved the sensitivity of electric leakage action at 50 He Zhi.L ₂Be the leak(age) test coil, after it utilizes the low-voltage alternating-current electrical short of capacitance decompression, L ₁Induce signal and make switch motion, whether working properly just can test out the earth leakage protective part.Current direction is from power supply A phase, coil L ₂, test knob AN, capacitor C ₉C ₁₀To power supply C phase.

This circuit adopts capacitance decompression halfwave rectifier mode, C ₉C ₁₀Series connection is gone up mutually at power supply C, and the positive half cycle of power supply obtains direct voltage through the D15 rectification, obtains 12 volts of direct voltages and use for gate circuit and monostable trigger-action circuit after R15D17 voltage stabilizing, C7 filtering.D14 provides a path to the power-half cycle.R16R17 is that capacitor C 9C10 residual voltage discharges resistance.

The last open phase protection of delivering in 1977 that illustrates that again this specification begins to mention can not detect the reason of return current open phase fault.Fig. 5 is the accompanying drawing according to former extracts.Fig. 5 (1) is the spike signal that square magnetic magnetic ferrites magnetic core coil is produced when sine-wave current magnetizes; (2) be three-phase current each coil spike figure that can not occur simultaneously just often; (3) be the spike figure that each coil occurs simultaneously that has no progeny in mutually.Can see that in Fig. 5 (1) spike is created in the moment of current over-zero; the waveform that contrasts Fig. 7 (1) so as can be known; waveform during three-phase current unbalance can obtain the spike figure of Fig. 5 (2) equally, and the three-phase imbalance electric current is non-detectable with this open phase protection from analyzing as can be known.

Claims (4)

1, a kind of circuit breaker, in insulation crust, contact system, overcurrent release system and detection of electrical leakage systematic order are electrically connected, and it is characterized in that: the overcurrent release system also surveys electric current with an electronic type three-phase imbalance check system and is connected.

2, circuit breaker according to claim 1 is characterized in that straight-through current transformer is the centre cap double winding secondary coil of being made by common silicon steel material.

3, circuit breaker according to claim 1 is characterized in that the negative OR circuit output point of three inputs, and the capacitor of connecting connects with monostable trigger-action circuit.

4, circuit breaker according to claim 1 is characterized in that monostable trigger-action circuit input high-frequency bypass capacitor in parallel over the ground.

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