CN101373207A - Method for detecting off-line type three-phase ac motor malfunction - Google Patents

Abstract

A method for detecting failures in a three-phase AC motor on an off-line basis relates to a method for detecting failures in a three-phase AC motor, so as to solve the problems that stator winding inter-turn short circuits and rotor failures can not be detected effectively, the severity of the failures can not be discriminated, misjudgment can be easily made, and the requirements for the technical level and the practical experience of the maintenance personnel are higher in the conventional method for detecting the failures in a motor. The method comprises the following steps: starting a device for detecting the failures in the three-phase AC motor on an off-line basis; measuring the phase-phase resistance of the stator winding of the three-phase AC motor and calculating the unbalanced degree of the phase-phase resistance; measuring the phase-phase inductance of the stator winding of the three-phase AC motor and calculating the unbalanced degree of the phase-phase inductance; measuring the phase-phase impedance of the stator winding of the three-phase AC motor and calculating the unbalanced degree of the phase-phase impedance; measuring the phase angle of the stator winding of the three-phase AC motor and calculating the maximum value of the phase angle difference; measuring the stator winding of the three-phase AC motor, and calculating to acquire the maximum value of the I/F difference; and determining whether the failures exist in the motor, the severity and the failure type according to the acquired values.

Description

A kind of method for detecting off-line type three-phase ac motor malfunction

Technical field

The present invention relates to a kind of fault detection method of three phase alternating current motor.

Background technology

Three phase alternating current motor has all obtained to use widely in departments such as railway, electric power, metallurgy, chemical industry as the topworks of Electric Traction, plays a part very important aborning.But, cause serious economy loss easily even cause great security incident because protection imperfection or improper use are often broken down.Motor type is a lot, and every class motor has different specifications, version and service condition again.The phenomenon of the failure more complicated of every kind of motor, the technical difficulty of its maintenance job is bigger, requires the maintenance personal to have higher technical merit and experience, could find and judge electrical fault.For a long time, the maintenance personal can only rely on dynamic electric test, static electric test, dynamic mechanically to test three class methods motor status is assessed.Basic electric faults such as the dynamic main test voltage imbalance of electric test, power quality, efficient; Static electric test mainly is the test of insulation resistance and direct current resistance, and many motor windings when breaking down resistance still keep balance, cause erroneous judgement; Main infrared analysis and the vibration analysis method of adopting of dynamic mechanically test is used to detect connectivity problem, misaligns problem and loading problem etc., and can point out air gap whether to have fault, but a large amount of practical experience of the application need of this method of testing.Differentiate motor with above-mentioned conventional method and whether have fault, can not differentiate the order of severity of fault, can not determine how long motor can also use, and more can not diagnose out the fault degree of rotor, erroneous judgement also often occurs.

Summary of the invention

The present invention for solve that the conventional motors fault detection method exists can not effectively detect stator winding inter-turn short circuit and rotor fault, can not differentiate the order of severity of fault, erroneous judgement easily, to the problem that maintenance personal's technical merit and practical experience are had relatively high expectations, a kind of method for detecting off-line type three-phase ac motor malfunction is provided.The present invention is realized by following steps:

Step 1: start the off-line type three-phase ac motor failure detector;

Step 2: record three phase alternating current motor stator winding phase-phase resistance R _AB, R _BCAnd R _CA, obtain phase-phase resistance degree of unbalancedness R by calculating _Imb

Step 3: record three phase alternating current motor stator winding phase-phase inductance L _AB, L _BCAnd L _CA, obtain phase-phase inductance degree of unbalancedness L by calculating _Imb

Step 4: record three phase alternating current motor stator winding phase-phase of impedance Z _AB, Z _BCAnd Z _CA, obtain phase-phase of impedance degree of unbalancedness Z by calculating _Imb

Step 5: record three phase alternating current motor stator winding phase angle Fi _AB, Fi _BCAnd Fi _CA, obtain phase angle difference maximal value Fi by calculating _Max

Step 6: record three phase alternating current motor stator winding I/F _AB, I/F _BC, I/F _CA, obtain I/F difference maximal value I/F by calculating _Max

Step 7: judge whether motor has the order of severity of fault and fault, judged result such as following table according to step 2 to each parameter value that step 6 obtains:

Step 8: according to the fault type of step 2 to each parameter value judgement motor of step 6 acquisition, judged result such as following table:

The electrical fault type	Measured value range
		Homophase, with the turn-to-turn short circuit of winding	(2<Fi max)and(3<I/F max)
Phase fault	(Fi max＝0)and(2<I/F max)
		With short circuit between the coil in the winding	(2<Fi max)and(I/F max＝0)
Joint is loosening	(I/F max＝0)and(Fi max＝0)and(5<R imb)
		Rotor fault	Three pole reactor and impedance increase simultaneously or reduce simultaneously
Rotor casting flaw or disconnected bar	Inductance or impedance are all uneven under the rotor different angles
		The winding fouling or overheating	Three pole reactor and impedance do not increase simultaneously or do not reduce simultaneously

Beneficial effect: the invention provides a kind of method for detecting off-line type three-phase ac motor malfunction based on static circuit analysis (MCA) method, faults such as it can detect effectively that motor stator winding turn-to-turn short circuit, phase fault, joint are loosening, winding pollution, rotor broken bar or casting flaw, and can judge the out of order order of severity, and technical merit and practical experience to the maintenance personal are less demanding, thereby, reduced the economic loss that electrical fault is brought for the safe and reliable operation of motor provides guarantee.

Description of drawings

Fig. 1 is a circuit structure diagram of using the off-line type three-phase ac motor failure detector of the method for the invention.

Embodiment

Referring to Fig. 1, present embodiment is made up of following steps:

Step 1: start the off-line type three-phase ac motor failure detector;

Step 2: record three phase alternating current motor stator winding phase-phase resistance R _AB, R _BCAnd R _CA, obtain phase-phase resistance degree of unbalancedness R by calculating _Imb

Step 3: record three phase alternating current motor stator winding phase-phase inductance L _AB, L _BCAnd L _CA, obtain phase-phase inductance degree of unbalancedness L by calculating _Imb

Step 4: record three phase alternating current motor stator winding phase-phase of impedance Z _AB, Z _BCAnd Z _CA, obtain phase-phase of impedance degree of unbalancedness Z by calculating _Imb

Step 5: record three phase alternating current motor stator winding phase angle Fi _AB, Fi _BCAnd Fi _CA, obtain phase angle difference maximal value Fi by calculating _Max

Step 6: record three phase alternating current motor stator winding I/F _AB, I/F _BC, I/F _CA, obtain I/F difference maximal value I/F by calculating _Max

Step 7: judge whether motor has the order of severity of fault and fault, judged result such as following table according to step 2 to each parameter value that step 6 obtains:

Step 8: according to the fault type of step 2 to each parameter value judgement motor of step 6 acquisition, judged result such as following table:

The electrical fault type	Measured value range
		Homophase, with the turn-to-turn short circuit of winding	(2<Fi max)and(3<I/F max)
Phase fault	(Fi max＝0)and(2<I/F max)
		With short circuit between the coil in the winding	(2<Fi max)and(I/F max＝0)
Joint is loosening	(I/F max＝0)and(Fi max＝0)and(5<R imb)

Rotor fault	Three pole reactor and impedance increase simultaneously or reduce simultaneously
		Rotor casting flaw or disconnected bar	Inductance or impedance are all uneven under the rotor different angles
The winding fouling or overheating	Three pole reactor and impedance do not increase simultaneously or do not reduce simultaneously

In the present embodiment, off-line type three-phase ac motor failure detector in the step 1 is the microcomputer type electrical fault pick-up unit based on single-chip microcomputer or DSP (digital signal processor), the electrical fault pick-up unit that is based on single-chip microcomputer C8051F023 that present embodiment adopted.Judge at first according to the result who records whether motor has the order of severity of fault and fault, wherein R _Imb, L _Imb, Z _Imb, Fi _MaxAnd I/F _MaxValue big more, represent the fault of motor serious more; Judge the fault type of judging motor after the electrical fault again.

Originally execute the off-line type three-phase ac motor failure detector described in the mode step 1 and comprise resistance measuring circuit 3, CPU and mould/number conversion circuit 6, the sinusoidal wave generation and amplitude/phase measuring circuit 1, frequency multiplication and amplitude measurement circuit 2 thereof, inductance measurement circuit 4 and impedance/phase angle/I/F frequency multiplication metering circuit 5, resistance measuring circuit 3, the sinusoidal wave generation and amplitude/phase measuring circuit 1, frequency multiplication and amplitude measurement circuit 2 thereof, the signal output part of inductance measurement circuit 4 and impedance/phase angle/I/F frequency multiplication metering circuit 5 is connected with the input end of analog signal of CPU and mould/number conversion circuit 6 respectively, sinusoidal wave generate and the sine wave signal output terminal of amplitude/phase measuring circuit 1 respectively with frequency multiplication and amplitude measurement circuit 2 thereof, inductance measurement circuit 4 is connected with the waveform signal input end of impedance/phase angle/I/F frequency multiplication metering circuit 5.

The method that records three phase alternating current motor stator winding phase-phase resistance in the step 2 in the present embodiment adopts voltammetry, finishes by the resistance measuring circuit in the off-line type three-phase ac motor failure detector 3, CPU and mould/number conversion circuit 6; Resistance measuring circuit 3 is made up of a connection terminal J1 and ten No. nine resistance R 19, first end of a connection terminal J1 is connected with+3.3V direct supply, second end of a connection terminal J1 is connected with first end of ten No. nine resistance R 19, the second end ground connection of ten No. nine resistance R 19;

CPU and mould/number conversion circuit 6 is that singlechip chip U5 and No. eight capacitor C 8 of C8051F023 are formed by model, the 1st, 2,3,4,5,25,40 and 56 pins of singlechip chip U5 are ground connection all, the 6th, 24 of singlechip chip U5 is connected with+3.3V direct supply with 57 pins, the first end ground connection of No. eight capacitor C 8, the 7th of second end of No. eight capacitor C 8 and singlechip chip U5 is connected with 8 pins, and first end of ten No. nine resistance R 19 all is connected with the 11st pin of singlechip chip U5 with second end of a connection terminal J1; The AB phase, BC that first end of a connection terminal J1 and second end are connected the motor stator winding extension line more respectively mutually and CA mutually, and record phase-phase resistance R respectively _AB, R _BCAnd R _CA, by formula R _Imb=(R _Max-R _Min)/R _AveCalculate and obtain phase-phase resistance degree of unbalancedness R _Imb, R wherein _MaxRepresent R _AB, R _BCAnd R _CAMaximal value, R _MinRepresent R _AB, R _BCAnd R _CAMinimum value, R _AveRepresent R _AB, R _BCAnd R _CAMean value.

Originally the inductance measurement of executing in the step 3 of mode generates and amplitude/phase measuring circuit 1 by the sine wave in the off-line type three-phase ac motor failure detector, frequency multiplication and amplitude measurement circuit 2 thereof, inductance measurement circuit 4 and CPU and mould/number conversion circuit 6 is realized: sinusoidal wave generation and amplitude/phase measuring circuit 1 thereof are the function generator chip U1 of MAX038 by model, an integrated operational amplifier U2A, a capacitor C 1, No. two capacitor C 2, No. three capacitor C 3, No. four capacitor C 4, a resistance R 1, No. two resistance R 2, No. three resistance R 3, No. four resistance R 4, No. five resistance R 5, No. six resistance R 6 and No. seven resistance R 7 are formed, first end of a capacitor C 1 and first end of a resistance R 1 all the 1st pin of and function generator chip U1 are connected, the second end ground connection of a capacitor C 1, the 10th pin of the second end and function generator chip U1 of a resistance R 1 is connected, the 5th pin of the first end and function generator chip U1 of No. two capacitor C 2 is connected, the second end ground connection of No. two capacitor C 2, the 8th pin of the first end and function generator chip U1 of No. two resistance R 2 is connected, the second end ground connection of No. two resistance R 2, the 17th pin of first end of No. three capacitor C 3 and function generator chip U1 all is connected with+5V power supply, the second end ground connection of No. three capacitor C 3, the 20th pin of first end of No. four capacitor C 4 and function generator chip U1 all is connected with-5V power supply, the second end ground connection of No. four capacitor C 4, the 2nd of function generator chip U1,3,6,7,9,11,12,13,15 and 18 pins are ground connection all, the 19th pin of function generator chip U1 is connected with first end of No. three resistance R 3, second end of No. three resistance R 3 is connected with first end of No. five resistance R 5, second end of No. five resistance R 5 all is connected with the positive input pin (i.e. the 3rd pin) of an integrated operational amplifier U2A with first end of No. four resistance R 4, second end of No. four resistance R 4 is connected with+1.6V power supply, first end of No. six resistance R 6 all is connected with the anti-phase input pin (i.e. the 2nd pin) of an integrated operational amplifier U2A with first end of No. seven resistance R 7, the second end ground connection of No. six resistance R 6, second end of No. seven resistance R 7 is connected with the output pin of an integrated operational amplifier U2A (i.e. the 1st pin), the 4th pin of an integrated operational amplifier U2A is connected with+12V power supply, the 11st pin ground connection of an integrated operational amplifier U2A, No. eight resistance R 8, first end of ride on Bus No. 11 resistance R 11 and ten No. two resistance R 12 all is connected with second end of No. three resistance R 3, sinusoidal wave generate and sine wave that amplitude/phase measuring circuit 1 generates through the input of No. three resistance R 3 as frequency multiplication and amplitude measurement circuit 2 thereof;

Frequency multiplication and amplitude measurement circuit 2 thereof are the analog multiplier chip U4 of MLT04 by model, No. two integrated operational amplifier U3A, No. three integrated operational amplifier U3B, No. four integrated operational amplifier U3C, No. five integrated operational amplifier U3D, No. five capacitor C 5, No. six capacitor C 6, No. seven capacitor C 7, No. eight resistance R 8, No. nine resistance R 9, No. ten resistance R 10, ride on Bus No. 11 resistance R 11, ten No. two resistance R 12, ten No. three resistance R 13, ten No. four resistance R 14, ten No. five resistance R 15, ten No. six resistance R 16, ten No. seven resistance R 17 and ten No. eight resistance R 18 are formed, second end of No. eight resistance R 8 is connected with the normal phase input end of No. two integrated operational amplifier U3A (i.e. the 3rd pin), the 4th pin of No. two integrated operational amplifier U3A is connected with+12V power supply, the 11st pin ground connection of No. two integrated operational amplifier U3A, first end of No. nine resistance R 9 and No. ten resistance R 10 all is connected with the inverting input (i.e. the 2nd pin) of No. two integrated operational amplifier U3A, second end of No. nine resistance R 9 and the output terminal of No. two integrated operational amplifier U3A (i.e. the 1st pin) all the 6th pin with analog multiplier chip U4 are connected, the second end ground connection of No. ten resistance R 10, the 2nd of analog multiplier chip U4,8,11 and 17 pins are ground connection all, the 5th pin of analog multiplier chip U4 and first end of No. six capacitor C 6 all are connected with+5V power supply, the second end ground connection of No. six capacitor C 6, the 14th pin of analog multiplier chip U4 and first end of No. seven capacitor C 7 all are connected with-5V power supply, the second end ground connection of No. seven capacitor C 7, second end of ride on Bus No. 11 resistance R 11 all is connected with the normal phase input end (i.e. the 5th pin) of No. three integrated operational amplifier U3B with first end of No. five capacitor C 5, the second end ground connection of No. five capacitor C 5, second end of ten No. two resistance R 12 all is connected with the inverting input (i.e. the 6th pin) of No. three integrated operational amplifier U3B with first end of ten No. three resistance R 13, second end of ten No. three resistance R 13 and the output terminal of No. three integrated operational amplifier U3B (i.e. the 7th pin) all the 7th pin with analog multiplier chip U4 are connected, the 9th pin of analog multiplier chip U4 is connected with the normal phase input end of No. four integrated operational amplifier U3C (i.e. the 10th pin), first end of ten No. four resistance R 14, first end of ten No. six resistance R 16 all is connected with the inverting input (i.e. the 9th pin) of No. four integrated operational amplifier U3C with the output terminal of No. four integrated operational amplifier U3C (i.e. the 8th pin), the second end ground connection of ten No. four resistance R 14, second end of ten No. six resistance R 16 is connected with the positive input pin (i.e. the 12nd pin) of No. five integrated operational amplifier U3D with first end of ten No. five resistance R 15, second end of ten No. five resistance R 15 is connected with+1.6V power supply, the first end ground connection of ten No. seven resistance R 17, second end of ten No. seven resistance R 17 all is connected with the anti-phase input pin (i.e. the 13rd pin) of No. five integrated operational amplifier U3D with first end of ten No. eight resistance R 18, and second end of ten No. eight resistance R 18 is connected with the output pin of No. five integrated operational amplifier U3D (i.e. the 14th pin); Second end of No. three resistance R 3 is connected with the input end 1 of a single-pole double-throw switch (SPDT) S1 of inductance measurement circuit 4, sinusoidal wave generate and sine wave that amplitude/phase measuring circuit 1 generates through frequency multiplication and amplitude measurement circuit 2 frequencys multiplication thereof after the input end 2 of a single-pole double-throw switch (SPDT) S1 in the output terminal of No. four integrated operational amplifier U3C (i.e. the 8th pin) and the inductance measurement circuit 4 be connected; First end of No. eight resistance R 8, ride on Bus No. 11 resistance R 11 and ten No. two resistance R 12 all is connected with second end of No. three resistance R 3, sinusoidal wave generate and sine wave that amplitude/phase measuring circuit 1 generates through the input of No. three resistance R 3 as frequency multiplication and amplitude measurement circuit 2 thereof;

Inductance measurement circuit 4 is by No. six integrated operational amplifier U2B, No. seven integrated operational amplifier U2D, No. two connection terminal J2, a single-pole double-throw switch (SPDT) S1, two No. ten resistance R 20, two ride on Bus No. 11 resistance R 21,20 No. two resistance R 22,20 No. three resistance R 23,20 No. four resistance R 24 is formed, the output terminal 3 of a single-pole double-throw switch (SPDT) S1 is connected with first end of two No. ten resistance R 20, second end of two No. ten resistance R 20 all is connected with the inverting input (i.e. the 6th pin) of U2B with first end of No. two connection terminal J2, the normal phase input end of No. six integrated operational amplifier U2B (i.e. the 5th pin) ground connection, first end of the output terminal of No. six integrated operational amplifier U2B (i.e. the 7th pin) and 20 No. two resistance R 22 all is connected with second end of No. two connection terminal J2, first end of second end of 20 No. two resistance R 22 and two ride on Bus No. 11 resistance R 21 all is connected with the positive input pin (i.e. the 12nd pin) of No. seven integrated operational amplifier U2D, second end of two ride on Bus No. 11 resistance R 21 is connected with+1.6V power supply, first end of 20 No. three resistance R 23 all is connected with the anti-phase input pin (i.e. the 13rd pin) of No. seven integrated operational amplifier U2D with first end of 20 No. four resistance R 24, the second end ground connection of 20 No. three resistance R 23, second end of 20 No. four resistance R 24 is connected with the output pin of No. seven integrated operational amplifier U2D (i.e. the 14th pin).

If sinusoidal wave generate and the voltage magnitude of the sine wave that amplitude/phase measuring circuit 1 generates promptly is input to the 9th pin of singlechip chip U5 by AIN0 (output terminal of an integrated operational amplifier U2A) is U through the voltage magnitude of the analog to digital converter conversion of singlechip chip U5 inside, the sine wave that records through its CPU again _IN0, the angular frequency of establishing the sine wave of generation is ω ₁(can determine ω by the resistance size of adjusting a resistance R 1 ₁Value); If the voltage magnitude of sine wave behind frequency multiplication and amplitude measurement circuit 2 thereof that generates promptly is input to the 10th pin of singlechip chip U5 by AIN1 (output terminals of No. five integrated operational amplifier U3D), through the analog to digital converter conversion of singlechip chip U5 inside, the voltage magnitude of the sine wave after the frequency multiplication that its CPU records is U again _IN1, the angular frequency of establishing the sine wave after the frequency multiplication is ω ₂, ω then ₂=2 ω ₁

First end of No. two connection terminal J2 and second end are connected the AB phase of motor stator winding extension line respectively, the input end 1 of a single-pole double-throw switch (SPDT) S1 is connected with the output terminal 3 of a single-pole double-throw switch (SPDT) S1 earlier, at this moment, if be input to the 12nd pin of singlechip chip U5, be U through the analog to digital converter conversion of singlechip chip U5 inside, the voltage magnitude that records through its CPU again by AIN3 (output terminals of No. seven integrated operational amplifier U2D) _IN3The input end 2 of a single-pole double-throw switch (SPDT) S1 is connected with the output terminal 3 of a single-pole double-throw switch (SPDT) S1 then, at this moment, if be input to the 12nd pin of singlechip chip U5, be U through the analog to digital converter conversion of singlechip chip U5 inside, the voltage magnitude that records through its CPU again by AIN3 _IN3'.

If ${\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="A200810064744E00131.png"\; state="\{\{state\}\}">A</figure-callout>}}_1=\frac{U_{\mathrm{IN}3}}{U_{\mathrm{IN}0}},$ ${\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="A200810064744E00131.png"\; state="\{\{state\}\}">A</figure-callout>}}_2=\frac{U_{\mathrm{IN}3}\&prime;}{U_{\mathrm{IN}0}},$ AB phase inductance then $L_{\mathrm{AB}}=R_{20}\sqrt{\frac{{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="A200810064744E00131.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}^2-{{\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="A200810064744E00131.png"\; state="\{\{state\}\}">A</figure-callout>}}_2}^2}{{{\mathrm{\&omega;}}_1}^2-{{\mathrm{\&omega;}}_2}^2}}.$ In like manner can record BC phase inductance L _BC, CA phase inductance L _CABy formula L _Imb=(L _Max-L _Min)/L _AveObtain phase-phase inductance degree of unbalancedness L by calculating _Imb, L wherein _MaxBe L _AB, L _BC, L _CAMaximal value, L _MinBe L _AB, L _BC, L _CAMinimum value, L _AveBe L _AB, L _BC, L _CAMean value.

Originally execute that impedance measurement in the step 4 of mode generates by the sine wave in the off-line type three-phase ac motor failure detector and amplitude/phase measuring circuit 1, impedance/phase angle/I/F frequency multiplication metering circuit 5 are finished.

Sinusoidal wave generate and sine wave that amplitude/phase measuring circuit 1 generates is input to the input end 1 of No. two single-pole double-throw switch (SPDT) S2 in impedance/phase angle/I/F frequency multiplication metering circuit 5 through No. three resistance R 3, sinusoidal wave through frequency multiplication and amplitude measurement circuit 2 frequencys multiplication thereof after the input end 2 of No. two single-pole double-throw switch (SPDT) S2 in the output terminal of No. four integrated operational amplifier U3C (i.e. the 8th pin) and the impedance/phase angle/I/F frequency multiplication metering circuit 5 be connected.

Impedance/phase angle/I/F frequency multiplication metering circuit 5 is by No. two single-pole double-throw switch (SPDT) S2, No. three connection terminal J3, No. eight integrated operational amplifier U2C, 20 No. five resistance R 25,20 No. six resistance R 26,20 No. seven resistance R 27,20 No. eight resistance R 28 and 20 No. nine resistance R 29 are formed, the output terminal 3 of No. two single-pole double-throw switch (SPDT) S2 is connected with first end of No. three connection terminal J3, one end of 20 No. five resistance R 25 and 20 No. seven resistance R 27 all is connected with second end of No. three connection terminal J3, the second end ground connection of 20 No. five resistance R 25, second end of 20 No. seven resistance R 27 all is connected with the positive input pin (i.e. the 10th pin) of No. eight integrated operational amplifier U2C with first end of 20 No. six resistance R 26, second end of 20 No. six resistance R 26 is connected with+1.6V power supply, first end of 20 No. eight resistance R 28 and 20 No. nine resistance R 29 all is connected with the anti-phase input pin (i.e. the 9th pin) of No. eight integrated operational amplifier U2C, the second end ground connection of 20 No. eight resistance R 28, second end of 20 No. nine resistance R 29 is connected with the output pin of No. eight integrated operational amplifier U2C (i.e. the 8th pin).

First end of No. three connection terminal J3 and second end are connected the AB phase of motor stator winding extension line respectively, and the input end 1 of No. two single-pole double-throw switch (SPDT) S2 is connected with the output terminal 3 of No. two single-pole double-throw switch (SPDT) S2.If be input to the 9th pin of singlechip chip U5, be U through the voltage magnitude of the analog to digital converter conversion of singlechip chip U5 inside, the sine wave that records through its CPU again by AIN0 _IN0If be input to the 13rd pin of singlechip chip U5, be U through the voltage magnitude of the analog to digital converter conversion of singlechip chip U5 inside, the sine wave that records through its CPU again by AIN4 _IN4

AB phase of impedance then $Z_{\mathrm{AB}}=R_{25}(\frac{U_{\mathrm{IN}0}}{U_{\mathrm{IN}4}}-1).$ In like manner can record BC phase of impedance Z _BC, CA phase of impedance Z _CABy formula Z _Imb=(Z _Max-Z _Min)/Z _AveObtain phase-phase of impedance degree of unbalancedness Z by calculating _Imb, Z wherein _MaxBe Z _AB, Z _BC, Z _CAMaximal value, Z _MinBe Z _AB, Z _BC, Z _CAMinimum value, Z _AveBe Z _AB, Z _BC, Z _CAMean value.

Originally execute that phase angle measurement in the step 5 of mode generates by the sine wave in the off-line type three-phase ac motor failure detector and amplitude/phase measuring circuit 1, impedance/phase angle/I/F frequency multiplication metering circuit 5 are finished.

First end of No. three connection terminal J3 and second end are connected the AB phase of motor stator winding extension line respectively, and the input end 1 of No. two single-pole double-throw switch (SPDT) S2 is connected with the output terminal 3 of No. two single-pole double-throw switch (SPDT) S2.If be input to the 9th pin of singlechip chip U5, be Fi through the phase angle of the analog to digital converter conversion of singlechip chip U5 inside, the sine wave that records through its CPU again by AIN0 _IN0If be input to the 13rd pin of singlechip chip U5, be Fi through the phase angle of the analog to digital converter conversion of singlechip chip U5 inside, the sine wave that records through its CPU again by AIN4 _IN4Phase angle Fi then _AB=Fi _IN0-Fi _IN4In like manner can record Fi _BC, Fi _CAObtain Fi by calculating _AB, Fi _BC, Fi _CABetween the maximal value Fi of phase angle difference _Max

Originally executing I/F frequency multiplication in the step 6 of mode measures by the generation of the sine wave in the off-line type three-phase ac motor failure detector and amplitude/phase measuring circuit 1, frequency multiplication and amplitude measurement circuit 2 thereof, impedance/phase angle/I/F frequency multiplication metering circuit 5 and finishes.

The AB phase of the two termination motor stator winding extension lines of No. three connection terminal J3, the input end 1 of No. two single-pole double-throw switch (SPDT) S2 is connected with the output terminal 3 of S2 earlier, at this moment, if be input to the 13rd pin of singlechip chip U5, be U through the analog to digital converter conversion of singlechip chip U5 inside, the voltage magnitude that records through its CPU again by AIN4 (output terminals of No. eight integrated operational amplifier U2C) _IN4The input end 2 of S2 connects the output terminal 3 of S2 then, at this moment, establishes the 13rd pin that is input to singlechip chip U5 by AIN4, is U through the analog to digital converter conversion of singlechip chip U5 inside, the voltage magnitude that records through its CPU again _IN4`.

Then $I/F_{\mathrm{AB}}=\frac{U_{\mathrm{IN}4}\&prime;}{U_{\mathrm{IN}4}}.$ In like manner can record I/F _BC, I/F _CAObtain I/F by calculating _AB, I/F _BC, I/F _CABetween the difference maximal value I/F _Max

Claims (1)

1. method for detecting off-line type three-phase ac motor malfunction is characterized in that it is realized by following steps:

Step 1: start the off-line type three-phase ac motor failure detector;

Step 2: record three phase alternating current motor stator winding phase-phase resistance R _AB, R _BCAnd R _CA, obtain phase-phase resistance degree of unbalancedness R by calculating _Imb

Step 3: record three phase alternating current motor stator winding phase-phase inductance L _AB, L _BCAnd L _CA, obtain phase-phase inductance degree of unbalancedness L by calculating _Imb

Step 4: record three phase alternating current motor stator winding phase-phase of impedance Z _AB, Z _BCAnd Z _CA, obtain phase-phase of impedance degree of unbalancedness Z by calculating _Imb

Step 5: record three phase alternating current motor stator winding phase angle F _IAB, F _IBCAnd F _ICA, obtain phase angle difference maximal value F by calculating _Imax

Step 6: record three phase alternating current motor stator winding I/F _AB, I/F _BC, I/F _CA, obtain I/F difference maximal value I/F by calculating _Max

Step 7: judge whether motor has the order of severity of fault and fault, judged result such as following table according to step 2 to each parameter value that step 6 obtains:

Step 8: according to the fault type of step 2 to each parameter value judgement motor of step 6 acquisition, judged result such as following table:

The electrical fault type Measured value range Homophase, with the turn-to-turn short circuit of winding (2<Fi _max)and(3<I/F _max) Phase fault (Fi _max＝0)and(2<I/F _max) With short circuit between the coil in the winding (2<Fi _max)and(I/F _max＝0) Joint is loosening (I/F _max＝0)and(Fi _max＝0)and(5<R _imb) Rotor fault Three pole reactor and impedance increase simultaneously or reduce simultaneously Rotor casting flaw or disconnected bar Inductance or impedance are all uneven under the rotor different angles The winding fouling or overheating Three pole reactor and impedance do not increase simultaneously or do not reduce simultaneously 。

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