CN1094863A - The guard method of three-phase electric equipment and automatic protector for electrical equipment thereof - Google Patents
The guard method of three-phase electric equipment and automatic protector for electrical equipment thereof Download PDFInfo
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- CN1094863A CN1094863A CN 93104791 CN93104791A CN1094863A CN 1094863 A CN1094863 A CN 1094863A CN 93104791 CN93104791 CN 93104791 CN 93104791 A CN93104791 A CN 93104791A CN 1094863 A CN1094863 A CN 1094863A
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Abstract
A kind of three-phase electric equipment, the guard method that is particularly useful for three phase electric machine and automatic protector for electrical equipment thereof of being used for; it is characterized in that, change into the phase voltage of three phase supply power supply corresponding and have three line voltages of common reference potential point with the line voltage of described power supply.According to the variation of this line voltage electric equipment, especially motor are carried out negative sequence component, overvoltage, protection such as under-voltage.This automatic protector for electrical equipment also comprises the current protection part, and this part can be carried out protections such as short circuit, the phase failure, current imbalance, overcurrent and anti-frequent operation to load current.
Description
The present invention relates to a kind ofly to be used for the three-phase electric equipment, be particularly useful for the guard method of three phase electric machine and with the automatic protector for electrical equipment of this method design.
Owing to the variation of load, it is asymmetric to cause that three phase mains becomes under the symmetrical threephase source normal condition.Load is except three phase symmetry load, also be connected to the input or the excision of many single-phase loads, each large capacity single phase load, phase voltage all can change, thereby cause the variation of line voltage, it will cause produce between the line electric voltage over press of power supply, under-voltage, the line voltage uneven, therefore, the supply voltage phenomenon of symmetry fully is relative, and the asymmetric phenomenon of voltage is absolute.
The imbalance of three phase mains asymmetric meeting causing threephase load electric current.The power line broken string, joint loose contact and electric equipment internal fault etc. all can make the imbalance of load current more serious.Therefore, the unbalanced phenomenon of the load current of three-phase electric apparatus equipment also is absolute.
It is not all right that single overcurrent protection is only adopted in the protection of three-phase electric apparatus equipment.Must they be identified at the initial stage that above-mentioned abnormal conditions occurs, in the time might threatening the electric equipment safe operation, cut off the electricity supply, and can not wait until that fault progression just cuts off the electricity supply to the critical condition of device damage.Not so, electric equipment damages easily, and will shorten greatly its useful life.
Three-phase electric apparatus equipment mainly is threephase motor, and with the line voltage power supply of three phase mains, therefore threaten the change in voltage of motor safe operation is the line Voltage unbalance to threephase motor, and line overtension or low excessively usually.The negative sequence component that the imbalance of line voltage causes must rely on the unbalance protection of line voltage to protect.
In three phase mains; each line voltage swing is by corresponding two phase voltages decision; therefore the size of outlet voltage and the difference between the line voltage can not be directly reacted in the variation of phase voltage simultaneously, and this just causes being difficult to be realized by the variation of phase voltage calculation outlet voltage with simple hardware circuit the various overproof protection of the line voltage of three phase electric machine.
Main purpose of the present invention is to propose a kind of phase voltage with the three phase supply power supply and changes into proportional and have the guard method of three-phase electric equipment of three line voltages of common reference potential point and an automatic protector for electrical equipment that is made of this method with this power line voltage.
The method and apparatus that provided is provided, can realizes representing the line Voltage unbalance protection of motor negative sequence component.
A further object of the present invention is that the method and apparatus that is provided can realize the overvoltage and the under-voltage protection of line voltage.
Another purpose of the present invention is that the method and apparatus that is provided can realize the electric apparatus of load capability of overload of three-phase, short circuit and load current unbalance protection.
Another purpose of invention is that the method and apparatus that is provided can realize the logic open phase protection.
Of the present invention also have a purpose to be that the method and apparatus that is provided can have the function of anti-frequent operation.
The guard method that is used for the three-phase electric equipment, is particularly useful for three phase electric machine of the present invention, described three-phase electric equipment is with the threephase load electric current
Work is characterized in that it is the guard method with line voltage of common reference potential point that described guard method comprises the three phase supply power conversion, and described line voltage protection method comprises step and is:
(a) extract three and the proportional phase voltage of each phase voltage of described three phase mains from the three phase mains of giving the electric power devices of described three-phase
(b) with above-mentioned phase voltage
Be transformed to proportional and have three line voltages of common reference potential point with each line voltage of described three phase supply power supply
;
(c) according to described three line voltages
Variation described three-phase electric equipment, especially three phase electric machine are carried out the protection of thrin at least of line Voltage unbalance, overvoltage, under voltage.
Line Voltage unbalance protection in the described step (c) can further comprise:
With described line voltage
Change three and the proportional line voltage of each line voltage magnitude D. C. value U into
AB, U
BC, U
CA;
With above-mentioned three line voltage D. C. value U
AB, U
BC, U
CASubtract each other in twos is U
AB-U
BC, U
BC-U
CA, U
CA-U
ABForm corresponding and represent the Voltage unbalance signal △ U of the line voltage direct current difference of motor negative sequence component size with the difference of line voltage magnitude in twos
AB, △ U
BC, △ U
CA;
With the above-mentioned voltage signal △ U that do not weigh
AB, △ U
BC, △ U
CAIn each compare with a reference voltage and a negative reference voltage of predetermined representative motor negative sequence component size separately, as arbitrary described Voltage unbalance signal △ U
AB, △ U
BC, △ U
CAProduce line Voltage unbalance guard signal during greater than described reference voltage or less than negative reference voltage;
Promote the protection executive circuit to finish the protection of line Voltage unbalance with described line Voltage unbalance guard signal.
Overvoltage protection in the described step (c) can further comprise step:
With described line voltage D. C. value U
AB, U
BC, U
CACompare with an overvoltage reference voltage separately, as line voltage D. C. value U
AB, U
BC, U
CAAny produce the overvoltage protection signal during less than described overvoltage reference voltage;
Promote described protection executive circuit with described overvoltage protection signal and finish overvoltage protection.
Overvoltage protection in the described step (c) can further comprise step:
With described line voltage D. C. value U
AB, U
BC, U
CACompare with an overvoltage reference voltage separately, as line voltage D. C. value U
AB, U
BC, U
CAAny produce the under voltage protection signal during less than described under voltage reference voltage;
Promote described protection executive circuit with described under voltage protection signal and finish under voltage protection.
Described guard method can further comprise current protection, and described current protection comprises step and is:
(a) with the described threephase load electric current I in the described three-phase electric apparatus equipment of powered operation
A, I
B, I
CBe converted to corresponding three-phase alternating current, magnitude of voltage
;
(b) with above-mentioned three-phase alternating voltage value
Change into its amplitude also promptly with the threephase load electric current
The proportional three-phase dc magnitude of voltage of amplitude U
a, U
b, U
c;
(c) with above-mentioned dc voltage value U
a, U
b, U
cEach compare with a plurality of predetermined reference voltage levels respectively corresponding to overcurrent, when described three-phase dc voltage U
a, U
b, U
cIn any greater than in described a plurality of reference voltages any and produce the load over-current guard signal when continue surpassing in time with the corresponding predetermined time interval of this reference voltage;
(d) described overcurrent protection signal is promoted described protection executive circuit and finish the load over-current protection.
Described current protection also can comprise the load short circuits protection, the steps include:
With described three-phase dc voltage U
a, U
b, U
cEach compare with a predetermined reference voltage respectively corresponding to load short circuit current, when described three-phase dc voltage U
a, U
b, U
cIn any during greater than described reference voltage the output protection signal drive described protection executive circuit and finish the load short circuits protection.
Described current protection further comprises the power supply open phase protection, the steps include:
According to logical relation
Be three-phase when simultaneously load current being arranged corresponding to run well or three-phase simultaneously during no-load current corresponding to not powering up and not exporting the open phase protection signal to load, output one open phase protection signal promotes the protection executive circuit and realizes open phase protection under other arbitrary phase failure state.
Described current protection can further comprise the load current unbalance protection, the steps include:
With described three-phase dc voltage U
a, U
b, U
cSubtract each other in twos is U
a-U
b, U
b-U
c, U
c-U
aForm and the threephase load electric current
The corresponding voltage difference △ of difference in magnitude U in twos
a, △ U
b, △ U
c;
With above-mentioned voltage difference △ U
a, △ U
b, △ U
cEach each compare with the reference voltage and the negative reference voltage of a predetermined difference corresponding to load current, as arbitrary described voltage difference △ U
a, △ U
b, △ U
cOr △ U
cGeneration load current unbalance protection signal drives described protection executive circuit and finishes the load current unbalance protection during greater than described reference voltage or less than negative reference voltage.
Described guard method can further comprise anti-frequent operation, the steps include:
When the moment excision of described three-phase electric apparatus apparatus of load, described three-phase dc voltage U corresponding to load current
a, U
b, U
cBe zero, when described three-phase dc voltage U
a, U
b, U
cBe to produce an anti-frequent operation signal driving when the zero time surpassing a scheduled time to protect executive component to cut off described power supply, when described three-phase voltage U
a, U
b, U
cBe zero time remaining when surpassing another longer scheduled time, described anti-frequent operation signal disappears automatically, and power supply is connected.
The three-phase electric apparatus automatic protector that designs with the guard method of the described three-phase electric equipment of claim 1 of the present invention, described three-phase electric equipment is with the threephase load electric current
Work is characterized in that described three-phase electric apparatus automatic protector comprises the voltage protection part, and described voltage protection partly comprises:
Receive three-phase voltage, output and the proportional phase voltage U of each phase voltage of described three phase mains of the three phase mains of giving described three-phase electric apparatus power devices
A, U
B, U
CThe phase voltage transducer;
Phase voltage U with above-mentioned phase voltage transducer output
A, U
B, U
CChange and export three proportional and have the line voltage of common reference potential point with each line voltage of three phase mains
; The line voltage generator;
Line voltage with above-mentioned line voltage generator output
Conversion produces corresponding to described line voltage
Maximum difference and represent the maximum line voltage unbalanced signal of motor negative sequence component size between the amplitude, and produce during greater than certain predetermined value and the unbalance protection signal generator of output line voltage unbalance protection signal when the absolute value of described maximum unbalanced signal;
Unbalance protection signal by described unbalance protection signal generator output drives its action and carries out the protection executive circuit that related circuit is protected.
Described unbalance protection signal generator can further comprise:
With described line voltage
; Change three and the proportional line voltage of each line voltage magnitude D. C. value U into
AB, U
BC, U
CAThe AC line voltage converter;
With above-mentioned three line voltage D. C. value U
AB, U
BC, U
CASubtract each other in twos is U
AB-U
BC, U
BC-U
CA, U
CA-U
ABProduce corresponding and represent the Voltage unbalance signal U of the line voltage direct current difference of motor negative sequence component size with the difference of the amplitude of described line voltage in twos
AB, U
BC, U
CALine Voltage unbalance signal generator;
With above-mentioned line Voltage unbalance signal △ U
AB, △ U
BC, △ U
CAEach compare with a reference voltage and a negative reference voltage of predetermined representative motor negative sequence component size, as arbitrary described line Voltage unbalance signal △ U
AB, △ U
BC, △ U
CAProduce and be defeated by the uneven comparator of generating positive and negative voltage of described protection executive circuit line Voltage unbalance guard signal during greater than described reference voltage or less than negative reference voltage.
Described voltage protection part can further comprise:
With described line voltage D. C. value U
AB, U
BC, U
CAEach compares with an overvoltage reference voltage, as line voltage D. C. value U
AB, U
BC, U
CAAny produce the over-voltage comparator that the overvoltage protection signal is defeated by described protection executive component during greater than described overvoltage reference voltage;
With described line voltage D. C. value U
AB, U
BC, U
CAEach compares with a under voltage reference voltage, as line voltage D. C. value U
AB, U
BC, U
CAAny produce the under voltage comparator that the under voltage protection signal is defeated by described protection executive circuit during less than described under voltage reference voltage.
Described protector can further comprise the current protection part, and described current protection partly comprises:
With the described threephase load electric current I in the described three-phase electric apparatus equipment of powered operation
A, I
B, I
CChange corresponding three-phase alternating voltage value into
Current transformer;
With above-mentioned three-phase alternating voltage value U
a, U
b, U
cChange into its amplitude also promptly with the threephase load electric current
The proportional three-phase dc magnitude of voltage of amplitude U
a, U
b, U
cRectifier filter;
With above-mentioned dc voltage value U
a, U
b, U
cEach compare with a plurality of predetermined reference voltage levels respectively corresponding to overcurrent, when described three-phase dc voltage U
a, U
b, U
cIn any greater than any in described a plurality of reference voltages and the overcurrent protection signal generator that produces the load over-current guard signal and this signal is defeated by described protection executive circuit when continue surpassing in time with the corresponding predetermined time interval of this reference voltage.
Described current protection part can further comprise:
With described three-phase dc voltage U
a, U
b, U
cEach compare with a predetermined reference voltage corresponding to load short circuit current, when described three-phase dc voltage U
a, U
b, U
cIn any during greater than described reference voltage the output short circuit current guard signal give the short circuit comparator of described executive circuit;
According to logical relation
Produce an open phase protection signal and be defeated by the phase failure protector of described executive component;
When the moment excision of described three-phase electric apparatus apparatus of load, when three-phase dc voltage U corresponding to load current
a, U
b, U
cBe to produce an anti-frequent operation signal driving when the zero time surpassing a scheduled time to protect executive circuit to cut off described power supply; and when described be that zero time remaining is when surpassing another longer scheduled time; described anti-frequent operation signal disappears automatically, the anti-frequent operation circuit that power supply is connected.
Described current segment further can comprise:
With described three-phase dc voltage U
a, U
b, U
cSubtract each other in twos is U
a-U
b, U
b-U
c, U
c-U
aForm and the threephase load electric current
The corresponding voltage difference △ of difference in magnitude U in twos
a, △ U
b, △ U
cThe current imbalance generator;
With above-mentioned voltage difference △ U
a, △ U
b, △ U
cEach each compare with the reference voltage and the negative reference voltage of a predetermined width of cloth difference corresponding to load current, as arbitrary described voltage difference △ U
a, △ U
bOr △ U
cProduce load current unbalance protection signal during greater than described reference voltage or less than negative reference voltage and give the positive and negative current imbalance comparator of described protection executive circuit.
The guard method of three-phase electric equipment of the present invention as mentioned above and automatic protector for electrical equipment thereof; it is proportional and have three line voltages of common reference potential point with the line voltage of this three phase mains that its core inventive point is that the phase voltage with three phase mains is transformed to; thereby realized having finished the negative sequence component protection of the three phase electric machine of explaining with the line Voltage unbalance with the simple hardware construction circuit; in addition, method and apparatus of the present invention also has functions such as protection such as overvoltage, under-voltage, overcurrent, short circuit, current imbalance, the logic phase failure and anti-frequent operation.
Describe the present invention in detail below in conjunction with drawings and Examples.
Fig. 1 is the structured flowchart of line Voltage unbalance protection part of the present invention;
Fig. 2 (a) and (b) are the line map of two specific embodiments of Fig. 1 neutral voltage generator 2;
Fig. 3 (a) and (b) are two specific embodiment structure charts of Fig. 1 neutral voltage unbalance protection signal generator 3;
Fig. 4 is the functional-block diagram of the whole preferred embodiment of automatic protector for electrical equipment of the present invention;
Fig. 5 is an embodiment electrical schematic diagram of anti-frequent operation circuit in the automatic protector for electrical equipment of the present invention.
Referring to Fig. 1, Fig. 1 is a line Voltage unbalance protection part of finishing main purpose of the present invention.Phase voltage transducer 1 can be by circuits such as electric resistance partial pressure, capacitance partial pressure or transformers with the output of the three phase mains dividing potential drop of its input and have three phase voltages of common reference potential point among the figure
Referring to Fig. 2 (a) and (b), the line voltage generator 2 among Fig. 1 can use shown in Fig. 2 (a) and (b) circuit with the phase voltage of its input
Change into three have the common reference potential point and with the proportional line voltage of each line voltage of power supply
Fig. 2 (a) is a scale operation amplifier, and it is output as
Be the line voltage between A phase, the B phase.Fig. 2 (b) is a transformer, its elementary termination A phase
A, another termination B phase
B, its secondary output line voltage then
ABAll the other line voltages
BC,
CAAvailable as above same circuit obtains.
Line Voltage unbalance guard signal generator 3 among Fig. 1 is with the line voltage of its input
AB,
BC,
CAConversion produces corresponding to line voltage
AB,
BC,
CAThe D. C. value U of amplitude
AB, U
BC, U
CA; And get these voltage U
AB, U
BC, U
CABetween the threshold value of the maximum negative sequence component that allows of maximum difference (it represents the maximum of motor negative sequence component) and a predetermined representative motor compare, when described maximum difference is exported a line Voltage unbalance guard signal during greater than this threshold value.
Referring to Fig. 3 (a) and (b), two specific embodiments of line Voltage unbalance guard signal generator have been provided here.Fig. 3 (a) illustrated embodiment comprises: rectifier filter 31, line Voltage unbalance generator 32, the uneven comparator 33 of positive voltage, the uneven comparator 34 of negative voltage and or door 35.Rectifier filter 31 is general as all-wave, half-wave, bridge rectifier filter circuit, three road ac line voltages
AB,
BC,
CAEach corresponding rectifier filter 31.Rectifier filter 31 is output as and line voltage
AB,
BC,
CAEach proportional line voltage D. C. value U of amplitude
AB, U
BC, U
CA
The subtraction circuit of three operational amplifiers shown in similar Fig. 2 of line Voltage unbalance generator 32 usefulness (a) is to above-mentioned line voltage D. C. value U
AB, U
BC, U
CASubtract each other in twos, i.e. U
AB-U
BC, U
BC-U
CA, U
CA-U
ABWith produce with ac line voltage in twos (
AB,
BC,
CA) the difference of amplitude corresponding and represent the Voltage unbalance signal △ U of the line voltage direct current difference of motor negative sequence component size
AB, △ U
BC, △ U
CAVoltage unbalance signal △ U
AB, △ U
BC, △ U
CAIn can comprise an absolute value maximum and represent the peaked voltage of motor negative sequence component.Because △ is U
AB, △ U
BC, △ U
CAIn which absolute value maximum do not know, so must be with voltage △ U
AB, △ U
BC, △ U
CAEach compares with the uneven comparator 34 of negative voltage that a uneven comparator 33 and of positive voltage with positive voltage set point of representing motor to allow maximum negative sequence component has above-mentioned ejusdem generis negative voltage set point.As Voltage unbalance signal △ U
AB, △ U
BC, △ U
CAIn arbitrary voltage greater than above-mentioned positive set point or less than above-mentioned negative set point, when promptly the absolute value of the maximum difference of representative voltage unbalanced signal surpasses the negative sequence component that motor allows, then by or door 35 outputs one line Voltage unbalance guard signal.Above-mentioned positive and negative Voltage unbalance comparator 33 and 34 can constitute with operational amplifier or this close top grade circuit; Voltage △ U
AB, △ U
BC, △ U
CABut the corresponding a pair of positive and negative Voltage unbalance comparator 33,34 of each voltage; Also can be with △ U
AB, △ U
BC, △ U
CABy one or door only connect a pair of above-mentioned comparator 33,34.Above-mentioned this class circuit belongs to conspicuous in the art technology, no longer launches here to describe.
Fig. 3 (b) has provided the embodiment of another line Voltage unbalance guard signal generator 3.Three ac line voltages of Fig. 1 neutral voltage generator 2 outputs with common reference potential point
AB,
BC,
CAImport three optocoupler components 36 among Fig. 3 (b) respectively; Again through filtering amplify three of 37 outputs each with line voltage
AB,
BC,
CAThe proportional line voltage of amplitude D. C. value U
AB, U
BC, U
CADirect voltage U
AB, U
BC, U
CABy one group or door D
1, D
2, D
3Insert the emitter-base bandgap grading of output triode T from a point; Three voltage U on the other hand
AB, U
BC, U
CABy one group and a door D
4, D
5, D
6From the b point through voltage-stabiliser tube D
7, resistance R
1Insert the base stage of triode T.Produce three voltage U at a point like this
AB, U
BC, U
CAIn maximum; And three voltage U appear in the b point
AB, U
BC, U
CAIn minimum value.So U
ABAll the time equal three voltage U
AB, U
BC, U
CAIn maximum difference, it is representing the operating maximum negative sequence component of motor.With voltage-stabiliser tube D
7Reverse-conducting voltage be chosen to be the maximum negative sequence component that corresponding motor allows, then work as U
AbGreater than D
7Reverse-conducting voltage the time triode T conducting, from its collector resistance R
2Export a line Voltage unbalance guard signal.
Return Fig. 1 now, the protection executive circuit 4 among Fig. 1 receives the line Voltage unbalance guard signal of above-mentioned line Voltage unbalance guard signal generator 3 outputs to finish the line Voltage unbalance protection corresponding to the motor negative sequence component.The protection executive circuit can be combinations such as triode-relay; Also can be combinations such as controllable silicon and/or relay.This is those skilled in the art's known technologies, no longer it is launched to describe here.
Referring to Fig. 4, Fig. 4 is the entire block diagram of the automatic protector for electrical equipment of a preferred embodiment of the present invention.In Fig. 4, the first half of its dotted line is a voltage protection part 42; The latter half is a current protection part 41.
Voltage protection part 42 comprises: by phase voltage transducer 1, line voltage generator 2, rectifier filter 31, line Voltage unbalance generator 32, the uneven comparator 33 of positive voltage, the uneven comparator 34 of negative voltage or door 35 and 53 cores of forming described in Fig. 1 and Fig. 3 (a) of finishing the line Voltage unbalance protection part of main purpose of the present invention of delaying time; By over-voltage comparator 43 and time-delay 54 and or door 36 form overvoltage protection; By under voltage comparator 44, time-delay 55 and or door 36 form under-voltage protection.
The line voltage D. C. value U of over-voltage comparator 43 filters of self-rectifying in the future 31
AB, U
BC, U
CAThrough or the door (not shown) after with over-voltage comparator in the overvoltage reference voltage set compare, as line voltage D. C. value U
AB, U
BC, U
CAIn any greater than described overvoltage with reference to the time produce the overvoltage protection signal through delay time 54 or door 36 and or door 38 remove to drive protection executive circuit 4 and finish the protection of line electric voltage over press.
The line voltage D. C. value U of under voltage comparator 44 filters of self-rectifying in the future 31
AB, U
BC, U
CAThrough or door (not shown) back and under voltage comparator in the under voltage reference voltage set compare, as line voltage D. C. value U
AB, U
BC, U
CAIn arbitrary voltage produce during less than described under voltage reference voltage the under voltage protection signal through delay time 55 or door 36 and or door 38 go to drive the under-voltage protection that protection executive circuit 4 is finished line voltage.Above-mentioned mistake, under voltage comparator 43,44 can constitute with operational amplifier or this close top grade circuit.These belong to apparent technology, repeat no more.Time-delay 53,54 and 55 general available RC integrating circuit constitute; their function is to make each guard signal time-delay a period of time output; if each guard signal is wide less than predetermined delay time; output protection signal not then has only when each guard signal time-delay is integrated to predetermined value (having certain pulse duration) to export.Above-mentioned delay circuit 53,54,55 can be finished the fast-changing effect of anti-power supply.
Current protection part 41 comprises: by current transformer 58,59,60, rectifier filter 48, overcurrent comparator 46 time-delays 56 overcurrent protections of forming; Phase failure protector 49; Anti-frequent operation circuit 47; By current imbalance generator 45, positive and negative current imbalance comparator 50,51 or door 37 and the 57 current imbalance protections of forming of delaying time.
Threephase load electric current by current transformer 58,59,60 during with machine operation
A,
B,
CChange corresponding three-phase alternating voltage value into
; Rectifier filter 48 is with the three-phase alternating voltage value
Change into its amplitude also promptly with the threephase load electric current
A,
B,
CThe proportional three-phase dc magnitude of voltage of amplitude U
a, U
b, U
cThe overcurrent comparator is made up of one group of comparator corresponding to a plurality of voltage setting values of different overcurrent sizes.Three-phase dc magnitude of voltage U
a, U
b, U
cThrough one or the door (not shown) insert this comparator, work as U
a, U
b, U
cIn any greater than in described a plurality of voltage setting values (reference voltage) any and when integration time-delay 56 continues to surpass with the corresponding predetermined time interval of this voltage setting value in time, then export an overcurrent protection signal through or door 39,38 drive protection executive circuits 4 and finish overcurrent protection.Overcurrent comparator 46 can be made up of operational amplifier or this close top grade circuit.
Phase failure protector 49 is one group of logic, and it is according to logical formula
Export an open phase protection signal through or door 39,38 drive protection executive circuits 4 and finish open phase protection.Constituting concrete circuit according to above-mentioned logical formula is to belong to apparent technology, is no longer discussed here.
Short circuit comparator 52 is with direct voltage U
a, U
b, U
cThrough one or door (not shown) and comparator 52 in the reference voltage corresponding to load short circuit current of setting compare, work as voltage U
a, U
b, U
cIn arbitrary voltage during greater than described reference voltage the output short circuit current guard signal through or door 39,38 drive protection executive circuits 4 and finish the short circuit current protection.
Anti-frequent operation circuit 47 is when the moment excision of three-phase electric apparatus apparatus of load, promptly
A,
B,
CEqual zero.Work as U
a, U
b, U
cBe produce when time of zero surpassing a scheduled time an anti-frequent operation signal through or door 39,38 drive protection executive circuits and finish the protection action of cutting off described power supply; and when surpassing another longer scheduled time for zero time remaining; make anti-frequent operation blackout, power supply is connected once more.
Anti-frequent operation circuit 47 can be made of logic and delay circuit.Fig. 5 provides an embodiment of anti-frequent operation circuit 47.D in Fig. 5
51, D
52, D
53Constitute positive or gate (also being negative and door), work as U
a, U
b, U
c(moment is when excising the power supply of motor) M point is by high potential step-down current potential when being suddenly zero, and inverter 55 is exported the short period T that high potentials are scheduled to through integration time-delay 56 time-delays one
1The back arrives the end with door 58, in time T
1In with the door 58 not conductings; M point current potential postpones the long period T that 57 time-delays one are scheduled to through integration on the other hand
2(T
2＞T
1) back arrives the other end with door 58; Because T
2＞T
1, when when an end reaches high potential above the door 58, the other end below it still keeps its M point voltage to become high potential before zero.So this moment and door 58 outputs one anti-frequent operation signal; As the T that postpones 57
2Time-delay finishes then to export an electronegative potential and closes with door 58 and finish anti-frequent operation.Though Fig. 5 provides an anti-frequent operation specific embodiment, the various variations that in fact this logical constitution and used device can be known just like technical staff in the art.
The line construction of current imbalance generator 45 and positive and negative current imbalance comparator 50,51 its effects is with line Voltage unbalance generator 32 and positive and negative Voltage unbalance comparator 33,34 in the voltage protection part.
Work as threephase load
A,
B,
CThen U takes place when uneven in (especially motor load)
a, U
b, U
cBetween have difference, 45 pairs in current imbalance generator and load current
A,
B,
CThe corresponding direct voltage U of amplitude
a, U
b, U
cSubtract each other in twos is U
a-U
b, U
b-U
c, U
c-U
aForm and the threephase load electric current
A,
B,
CThe corresponding voltage difference △ of difference in magnitude U in twos
a, △ U
b, △ U
c; △ U then
a, △ U
b, △ U
cIn positive and negative current imbalance comparator 50,51 with corresponding to the reference voltage and the negative reference voltage of load current amplitude difference, compare, as arbitrary voltage difference △ U
a, △ U
bOr △ U
cProducing load current unbalance protection signal warp or door 37, time-delay 57 or door 38 drivings during greater than described reference voltage or less than described negative reference voltage protects executive circuits 4 to finish the protection of threephase load current imbalance.The effect of time-delay 57, composition are with above-mentioned time-delay 53,54,55.
Protection executive circuit 4 can be chosen suitable element and usually according to the various protection executive circuits of the pattern of wants of working control from the devices such as switch of switch element, relay, contactor, controllable silicon and mechanical action; this is the technology that those skilled in the art know, and describes no longer for example here.
More than by various embodiment the present invention is described in detail.But these specific embodiments can not be as the qualification of scope of the present invention.Design of the present invention and technical scheme thereof will be limited by appended claims.
Claims (15)
1, a kind of guard method that is used for the three-phase electric equipment, is particularly useful for three phase electric machine, described three-phase electric equipment is with the threephase load electric current
Work is characterized in that it is that the guard method with line voltage of common reference potential point, described line voltage protection method comprise step and be that described guard method comprises the three phase supply power conversion:
(a) extract three and the proportional phase voltage of each phase voltage of described three phase mains from the three phase mains of giving the electric power devices of described three-phase
(b) with above-mentioned phase voltage
Be transformed to proportional and have three line voltages of common reference potential point with each line voltage of described three phase supply power supply
(c) according to described three line voltages
Variation described three-phase electric equipment, especially three phase electric machine are carried out the protection of thrin at least of line Voltage unbalance, overvoltage, under voltage.
2, guard method according to claim 1 is characterized in that, the line Voltage unbalance protection in the described step (C) can further comprise:
With described line voltage
Change three and the proportional line voltage of each line voltage magnitude D. C. value U into
AB, U
BC, U
CA;
With above-mentioned three line voltage D. C. value U
AB, U
BC, U
CASubtract each other in twos is U
AB-U
BC, U
BC-U
CA, U
CA-U
ABForm corresponding and represent the Voltage unbalance signal △ U of the line voltage direct current difference of motor negative sequence component size with the difference of line voltage magnitude in twos
AB, △ U
BC, △ U
CA;
With above-mentioned Voltage unbalance signal △ U
AB, △ U
BC, △ U
CAIn each compare with a reference voltage and a negative reference voltage of predetermined representative motor negative sequence component size separately, as arbitrary described Voltage unbalance signal △ U
AB, △ U
BC, △ U
CAProduce line Voltage unbalance guard signal during greater than described reference voltage or less than negative reference voltage;
Promote the protection executive circuit to finish the protection of line Voltage unbalance with described line Voltage unbalance guard signal.
3, guard method according to claim 1 is characterized in that, the overvoltage protection in the described step (C) can further comprise step:
With described line voltage D. C. value U
AB, U
BC, U
CACompare with an overvoltage reference voltage separately, as line voltage D. C. value U
AB, U
BC, U
CAAny produce the overvoltage protection signal during greater than described overvoltage reference voltage;
Promote described protection executive circuit with described overvoltage protection signal and finish overvoltage protection.
4, guard method according to claim 1 is characterized in that, the under voltage protection in the described step (C) can further comprise step:
With described line voltage D. C. value U
AB, U
BC, U
CACompare with a under voltage reference voltage separately, as line voltage D. C. value U
AB, U
BC, U
CAAny produce the under voltage protection signal during less than described under voltage reference voltage;
Promote described protection executive circuit with described under voltage protection signal and finish under voltage protection.
5, as guard method as described in the claim 1,2,3 or 4, it is characterized in that described guard method can further comprise current protection, described current protection comprises step and is:
(a) with the described threephase load electric current in the described three-phase electric apparatus equipment of powered operation
Be converted to corresponding three-phase alternating voltage value
;
(b) with above-mentioned three-phase alternating voltage value
Change into its amplitude also promptly with the threephase load electric current
The proportional three-phase dc magnitude of voltage of amplitude U
a, U
b, U
c;
(c) with above-mentioned dc voltage value U
a, U
b, U
cEach compare with a plurality of predetermined reference voltage levels respectively corresponding to overcurrent, when described three-phase dc voltage U
a, U
b, U
cIn any greater than in described a plurality of reference voltages any and produce the load over-current guard signal when continue surpassing in time with the corresponding predetermined time interval of this reference voltage;
(d) described overcurrent protection signal is promoted described protection executive circuit and finish the load over-current protection.
As guard method as described in the claim 5, it is characterized in that 6, described current protection also comprises the load short circuits protection, the steps include:
With described three-phase dc voltage U
a, U
b, U
cEach compare with a predetermined reference voltage respectively corresponding to load short circuit current, when described three-phase dc voltage U
a, U
b, U
cIn any during greater than described reference voltage the output protection signal drive described protection executive circuit and finish the load short circuits protection.
7, as guard method as described in the claim 5, it is characterized in that described current protection further comprises the power supply open phase protection, the steps include:
According to logical relation
Be three-phase when simultaneously load current being arranged corresponding to running well or three-phase is not exported the open phase protection signal corresponding to not powering up to load during no-load current simultaneously, output one open phase protection signal promotes the protection executive circuit and realizes open phase protection under other arbitrary phase failure state.
8, as guard method as described in the claim 5, it is characterized in that described current protection can further comprise the load current unbalance protection, the steps include:
With described three-phase dc voltage U
a, U
b, U
cSubtract each other in twos is U
a-U
b, U
b-U
c, U
c-U
aForm and the threephase load electric current
The corresponding voltage difference △ of difference in magnitude U in twos
a, △ U
b, △ U
c;
With above-mentioned voltage difference △ U
a, △ U
b, △ U
cEach each compare with the reference voltage and the negative reference voltage of a predetermined difference corresponding to load current, as arbitrary described voltage difference △ U
a, △ U
b, or △ U
cGeneration load current unbalance protection signal drives described protection executive circuit and finishes the load current unbalance protection during greater than described reference voltage or less than negative reference voltage.
9, as guard method as described in the claim 5, it is characterized in that described guard method can further comprise anti-frequent operation, the steps include:
When described three-phase electric apparatus apparatus of load moment is cut, described three-phase dc voltage U corresponding to load current
a, U
b, U
cBe zero, when described three-phase dc voltage U
a, U
b, U
cBe to produce an anti-frequent operation signal driving when the zero time surpassing a scheduled time to protect executive component to cut off described power supply, when described three-phase voltage U
a, U
b, U
cBe zero time remaining when surpassing another longer scheduled time, described anti-frequent operation signal disappears automatically, and power supply is connected.
10, a kind of three-phase electric apparatus automatic protector that designs with the guard method of the described three-phase electric equipment of claim 1, described three-phase electric equipment is with the threephase load electric current
Work is characterized in that described three-phase electric apparatus automatic protector comprises the voltage protection part, and described voltage protection partly comprises:
Receive three-phase voltage, output and the proportional phase voltage of each phase voltage of described three phase mains of the three phase mains of giving described three-phase electric apparatus power devices
The phase voltage transducer;
Phase voltage with above-mentioned phase voltage transducer output
Change and export three proportional and have the line voltage of common reference potential point with each line voltage of three phase mains
The line voltage generator;
Line voltage with above-mentioned line voltage generator output
Conversion produces corresponding to described line voltage
Maximum difference and represent the maximum line voltage unbalanced signal of motor negative sequence component size between the amplitude, and produce during greater than certain predetermined value and the unbalance protection signal generator of output line voltage unbalance protection signal when the absolute value of described maximum unbalanced signal;
Unbalance protection signal by described unbalance protection signal generator output drives its action and carries out the protection executive circuit that related circuit is protected.
11, as automatic protector as described in the claim 10, it is characterized in that described unbalance protection signal generator can further comprise:
With described line voltage
Change three and the proportional line voltage of each line voltage magnitude D. C. value U into
AB, U
BC, U
CAThe AC line voltage converter;
With above-mentioned three line voltage D. C. value U
AB, U
BC, U
CASubtract each other in twos is U
AB-U
BC, U
BC-U
CA, U
CA-U
ABProduce corresponding and represent the Voltage unbalance signal △ U of the line voltage direct current difference of motor negative sequence component size with the difference of the amplitude of described line voltage in twos
AB, △ U
BC, △ U
CALine Voltage unbalance signal generator;
With above-mentioned line Voltage unbalance signal △ U
AB, △ U
BC, △ U
CAEach compare with a reference voltage and a negative reference voltage of predetermined representative motor negative sequence component size, as arbitrary described line Voltage unbalance signal △ U
AB, △ U
BC, △ U
CAProduce and be defeated by the uneven comparator of generating positive and negative voltage of described protection executive circuit line Voltage unbalance guard signal during greater than described reference voltage or less than negative reference voltage.
As automatic protector as described in the claim 11, it is characterized in that 12, described voltage protection part can further comprise:
With described line voltage D. C. value U
AB, U
BC, U
CAEach compares with an overvoltage reference voltage, as line voltage D. C. value U
AB, U
BC, U
CAAny produce the over-voltage comparator that the overvoltage protection signal is defeated by described protection executive component during greater than described overvoltage reference voltage;
With described line voltage D. C. value U
AB, U
BC, U
CAEach compares with a under voltage reference voltage, as line voltage D. C. value U
AB, U
BC, U
CAAny produce the under voltage comparator that the under voltage protection signal is defeated by described protection executive circuit during less than described under voltage reference voltage.
13, as automatic protector as described in the claim 10,11 or 12, it is characterized in that described protector can further comprise the current protection part, described current protection partly comprises:
With the described threephase load electric current in the described three-phase electric apparatus equipment of powered operation
Change corresponding three-phase alternating voltage value into
Current transformer;
With above-mentioned three-phase alternating voltage value
Change into its amplitude also promptly with the threephase load electric current
The proportional three-phase dc magnitude of voltage of amplitude U
a, U
b, U
cRectifier filter;
With above-mentioned dc voltage value U
a, U
b, U
cEach compare with a plurality of predetermined reference voltage levels respectively corresponding to overcurrent, when described three-phase dc voltage U
a, U
b, U
cIn any greater than any in described a plurality of reference voltages and the overcurrent protection signal generator that produces the load over-current guard signal and this signal is defeated by described protection executive circuit when continue surpassing in time with the corresponding predetermined time interval of this reference voltage.
As automatic protector as described in the claim 13, it is characterized in that 14, described current protection part can further comprise:
With described three-phase dc voltage U
a, U
b, U
cEach compare with a predetermined reference voltage corresponding to load short circuit current, when described three-phase dc voltage U
a, U
b, U
cIn any during greater than described reference voltage the output short circuit current guard signal give the short circuit comparator of described executive circuit;
According to logical relation
Produce an open phase protection signal and be defeated by the phase failure protector of described executive component;
When the moment excision of described three-phase electric apparatus apparatus of load, when three-phase dc voltage U corresponding to load current
a, U
b, U
cBe to produce an anti-frequent operation signal driving when the zero time surpassing a scheduled time to protect executive circuit to cut off described power supply; and when described be that zero time remaining is when surpassing another longer scheduled time; described anti-frequent operation signal disappears automatically, the anti-frequent operation circuit that power supply is connected.
15, as automatic protector as described in the claim 14, it is characterized in that described current segment further can comprise:
With described three-phase dc voltage U
a, U
b, U
cSubtract each other in twos is U
a-U
b, U
b-U
c, U
c-U
aForm and the threephase load electric current
The corresponding voltage difference △ of difference in magnitude U in twos
a, △ U
b, △ U
cThe current imbalance generator;
With above-mentioned voltage difference △ U
a, △ U
b, △ U
cEach each compare with the reference voltage and the negative reference voltage of a predetermined amplitude difference corresponding to load current, as arbitrary described voltage difference △ U
a, △ U
b, △ U
cProduce load current unbalance protection signal during greater than described reference voltage or less than described negative reference voltage and give the positive and negative current imbalance comparator of described protection executive circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 93104791 CN1040929C (en) | 1993-04-20 | 1993-04-20 | Protective method for three-phase electrical equipment and automatic electrical appliance protector thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 93104791 CN1040929C (en) | 1993-04-20 | 1993-04-20 | Protective method for three-phase electrical equipment and automatic electrical appliance protector thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1094863A true CN1094863A (en) | 1994-11-09 |
| CN1040929C CN1040929C (en) | 1998-11-25 |
Family
ID=4985369
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 93104791 Expired - Fee Related CN1040929C (en) | 1993-04-20 | 1993-04-20 | Protective method for three-phase electrical equipment and automatic electrical appliance protector thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1040929C (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101976817A (en) * | 2010-09-08 | 2011-02-16 | 河南省电力公司洛阳供电公司 | Start-up protection method and device for commissioning of electric equipment |
| CN103618438A (en) * | 2013-11-28 | 2014-03-05 | 北京鼎汉技术股份有限公司 | Input harmonic wave cancellation method and device for three-phase double-bus power factor correction circuit |
| CN105429102A (en) * | 2015-12-22 | 2016-03-23 | 南京科远驱动技术有限公司 | Protection warning method and system for frequency converter equipped with multiple motors |
| CN106526361A (en) * | 2016-10-25 | 2017-03-22 | 珠海格力电器股份有限公司 | Three-phase drive plate fault determination circuit and three-phase drive plate |
| CN107247242A (en) * | 2017-07-31 | 2017-10-13 | Tcl空调器(中山)有限公司 | Frequency converter failure detection method and device |
| CN108988288A (en) * | 2018-06-27 | 2018-12-11 | 珠海格力电器股份有限公司 | Load short-circuit protection circuit and method and circuit system |
-
1993
- 1993-04-20 CN CN 93104791 patent/CN1040929C/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101976817A (en) * | 2010-09-08 | 2011-02-16 | 河南省电力公司洛阳供电公司 | Start-up protection method and device for commissioning of electric equipment |
| CN101976817B (en) * | 2010-09-08 | 2013-12-18 | 河南省电力公司洛阳供电公司 | Start-up protection method and device for commissioning of electric equipment |
| CN103618438A (en) * | 2013-11-28 | 2014-03-05 | 北京鼎汉技术股份有限公司 | Input harmonic wave cancellation method and device for three-phase double-bus power factor correction circuit |
| CN105429102A (en) * | 2015-12-22 | 2016-03-23 | 南京科远驱动技术有限公司 | Protection warning method and system for frequency converter equipped with multiple motors |
| CN106526361A (en) * | 2016-10-25 | 2017-03-22 | 珠海格力电器股份有限公司 | Three-phase drive plate fault determination circuit and three-phase drive plate |
| CN106526361B (en) * | 2016-10-25 | 2024-02-02 | 珠海格力电器股份有限公司 | Three-phase driving plate fault determining circuit and three-phase driving plate |
| CN107247242A (en) * | 2017-07-31 | 2017-10-13 | Tcl空调器(中山)有限公司 | Frequency converter failure detection method and device |
| CN108988288A (en) * | 2018-06-27 | 2018-12-11 | 珠海格力电器股份有限公司 | Load short-circuit protection circuit and method and circuit system |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1040929C (en) | 1998-11-25 |
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