CN1210268A - Method for insulation inspecting and ground protecting for windings of D. C. motor armature - Google Patents

Method for insulation inspecting and ground protecting for windings of D. C. motor armature Download PDF

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Publication number
CN1210268A
CN1210268A CN98111264A CN98111264A CN1210268A CN 1210268 A CN1210268 A CN 1210268A CN 98111264 A CN98111264 A CN 98111264A CN 98111264 A CN98111264 A CN 98111264A CN 1210268 A CN1210268 A CN 1210268A
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China
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voltage
point
insulation
winding
direct current
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CN98111264A
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CN1074131C (en
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许成金
冯士芬
彭辉
李自淳
刘福国
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Institute of Plasma Physics of CAS
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Institute of Plasma Physics of CAS
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Abstract

A method for testing the insulation of armature windings in DC dynamo and grounding protection is based on the theory that the grounding voltage for the motor with better insulation is a constant DC value, when winding insulation is damaged its grounding voltage is the sum of an alternative voltage and original constant DC voltage and when a winding is directly grounded, the peak-peak value of the alternative voltage is equal to the output voltage of dynamo. Measuring the voltage variation can dtermine the insulation condition of armature windings, so providing protection measurements.

Description

The insulation of direct current generator armature winding detects and earthing protecting method
The present invention relates to direct current generator and give the detection of anti-property, guard method.
The element of winding earth fault of direct current generator is one of major failure of direct current generator, and detection, protection must be set, and traditional method is after earth fault takes place, and the detection ground current is implemented to protect, and carries out careful inspection after the shutdown again.Commonly used have a pressure drop of measuring between commutator segment, measures the pressure drop and the examination lamp of commutator segment and between centers and check this three kinds of methods.During inspection, can select for use, also can take turns usefulness successively according to field condition and failure condition.
1. the pressure drop between the measurement commutator segment:
Low-voltage dc power supply is received on commutator segment and the axle, measured the pressure drop between adjacent commutator segment.The pressure drop direction will be opposite between the sheet of contiguous earth point, but pressure drop does not oppositely belong to this example on the commutator segment that joins with power supply.
2. measure the pressure drop of commutator segment and between centers:
Low-voltage dc power supply is received on two commutator segments of nearly pole span of being separated by, measured the pressure drop of commutator segment and between centers, the voltage drop value of earth point will be zero or very little.
3. examination lamp inspection:
Exchange the examination lamp with 220 volts and be connected on commutator segment and the axle, be advisable, burn out to prevent earth point with low power examination lamp, observed spark during according to test, smog, sound are judged the earth point position.
Protection, the inspection method of above-mentioned these direct current generator armature winding earth faults all are in fault the back to take place to implement protection, and then the trouble spot is checked; inspection method is loaded down with trivial details; need to shut down and to carry out, and accident takes place, caused economic loss.
Preventive inspection to the armature winding insulation is the method inspection that is used as AC voltage withstand test or comes the measurement insulation resistance value with megohmmeter; judge its insulation situation; equally only after shutting down, just can carry out; and be subjected to the influence of weather environmental change very big; withstand voltage test also might cause the damage to winding.
Each unit electromotive force of direct current generator armature winding leaks arbor by the insulation resistance of winding, between motor output end and arbor, just produced a voltage, usually be considered on electrical property, link together owing to " arbor---bearing seat---the earth " again, our method is by brush arbor and the earth to be linked together reliably, so we claim that it is a ground voltage.
By analysis, calculating and experimental verification, ground voltage is a constant DC quantity to the good motor in service that insulate, in case a certain winding insulation descends or destroys, ground voltage is superimposed upon on this constant DC quantity with regard to the voltage that an alternation is arranged, insulation descends many more, the peak-to-peak value of alternating voltage is just big more, and when the direct ground connection of a certain winding, the peak-to-peak value of alternating voltage will be the same with the output voltage of motor big.Detect the variation of this voltage and just can judge the insulation situation of armature winding, thereby preventive protection is provided, so that people overhauled with regard to planned arrangement before winding insulation destroys as yet fully, this is very beneficial to the safe operation that guarantees motor.
Purpose of the present invention just provides the method for a kind of direct current generator armature winding insulation detection and ground protection.
Fig. 1. the prototype synoptic diagram;
Fig. 2. ground voltage calculates waveform;
Fig. 3. test connection figure;
Fig. 4. ground voltage test waveform: Fig. 4 (a) is normal; The a certain winding insulation of Fig. 4 (b) descends: a certain winding insulation of Fig. 4 (c) is badly damaged; The a certain winding earth of Fig. 4 (d);
Fig. 5. protection action test circuit principle schematic.
Be described in detail below the present invention.
The computation model of ground voltage:
No matter the concrete coiling mode of direct current generator armature winding how, always can regard it as some parallel branches, and each winding can be regarded an independently electromotive force unit as, and the electromotive force unit that belongs to each bar branch road is connected in series successively, and each electromotive force unit addition is the output voltage of generator.
For ease of analyzing, the insulation resistance of each winding note is made R 1, concentrate to be labeled in the corresponding end of windings in series connection layout, each parallel branch isopotential point is connected, be reduced to the prototype of single branch road.Along with the rotation of motor, the prototype winding is moving, and induced potential is changing in the winding, and corresponding insulation resistance also moves forward, the E but the prototype electromotive force puts in order 1, E 2, E 3Constant, so can simulate the rotation of armature winding with the method that moves resistance toward complex line, the prototype synoptic diagram as shown in Figure 1.
By analyzing, calculating, can obtain following several expression formula:
1. the identical armature winding ground voltage of insulation resistance expression formula can be expressed as:
U d= 1/2E f (1)
In the formula: U a---the armature winding ground voltage
E f---the direct current generator output voltage
Formula (1) shows: the armature winding ground voltage that insulation resistance is identical is a constant DC quantity, numerically is half of direct current generator output end voltage, and is irrelevant with the insulation resistance size of winding.
2. when the simplex winding insulation resistance descends, the general expression formula of ground voltage:
If the insulation resistance of n winding drops to R n, then U dn = E f ( 1 / 2 ) + R i - R n m R n + R i [ Σ i = 0 n E i - ( 1 / 2 ) E f ] ( 0 ≤ n ≤ m ) - - - ( 2 ) In the formula: U Dn---the armature winding ground voltage
E i---unit winding electromotive force
E f---the direct current generator output voltage
R f---normal winding insulation against ground resistance
R n---insulation decline winding insulation against ground resistance
M---the effective number of windings of prototype
For ease of analyzing, we establish R n=(1/q) R i(q 〉=1), then (2) formula can be rewritten as: U dn = ( 1 / 2 ) E f + q - 1 m + q [ Σ i = 0 n E i - ( 1 / 2 ) E f ] ( 0 ≤ n ≤ m - - - ( a ) Formula (3) is told us, when a certain winding insulation of armature descends, the armature winding ground voltage no longer has been a single DC quantity, rotation along with motor, the position of insulation decline winding is changing, so ground voltage also changes thereupon, the voltage of this variation is superimposed upon on the DC quantity, becomes the DC voltage of a pulsation.The peak-to-peak value of alternation composition changes along with the degree of single winding insulation decline.
3. when the simplex winding insulation descended, the maximal value expression formula of ground voltage: by formula (3) as can be known, the maximal value of ground voltage appeared at Σ i = 0 n E i = E f The time, the expression formula of ground voltage can directly be listed as and write out at this moment. U dn max = E f ( 1 / 2 ) • · m + 2 q - 1 m + q - - - ( 4 )
Obviously, when winding insulation destroyed direct ground connection fully, when promptly q was infinitely great in (4) formula, the maximal value of ground voltage was exactly the positive and negative electrode output voltage of direct current generator, and has
U dnmax=E f (5)
4. when the simplex winding insulation descends, the minimum value of ground voltage
By (3) formula as can be known, the minimum value of ground voltage appears at expression formula Σ i = 0 n E i = 0 The time, the expression formula of ground voltage can directly be listed as and be written as at this moment U dn min = E f ( 1 / 2 ) · m + l m + q - - - ( 6 )
Obviously, when simplex winding insulation destroyed direct ground connection fully, the minimum value of ground voltage was 0, promptly has
U dnmin=0 (7)
5. the mean value of simplex winding ground voltage
Because the waveform of ground voltage is an alternation, symmetry, therefore U dnpj = U dn max + U dn min 2 = E f ( 1 / 2 ) - - - ( 8 )
(8) formula of observation, we can see that the mean value of ground voltage is only relevant with direct current generator positive and negative electrode output end voltage, and are irrelevant with each winding insulation resistance of armature.According to above-mentioned expression formula, we can draw out the oscillogram of direct current generator armature winding ground voltage at an easy rate, and for drawing conveniently, we suppose that Ei equates everywhere.
Direct current generator armature winding ground voltage calculates waveform as shown in Figure 2.
Can find out intuitively from scheming to go up us, the armature winding ground voltage be one with (1/2)E fBe superimposed with the dc pulse moving voltage of an alternating voltage for baseline.
Measured result and above-mentioned waveform match.
According to above formula, referring to accompanying drawing 5:
On motor shaft, adorn brush, draw arbor current potential D point; 2 of C, B are across the DC generator output voltage two ends; At the output terminal of direct current generator, get intermediate potential A point by divider resistance;
Work as U CB=E f, divider resistance R 1=R 2The time, U A= (1/2)E f, A point current potential is invariable; With the B point is potential reference point, U B=0, ground voltage U DExpression formula be formula (2), U D = E f ( 1 / 2 ) + R i - R n m R n + R i [ Σ i = 0 n E i - ( 1 / 2 ) E f ] When motor windings just often, U D= (1/2)E f, but when a certain winding insulation destroys, U D= (1/2)E fAdd alternating voltage, alternating voltage amplitude size is relevant with winding insulation decline degree, can judge the insulation situation in view of the above.
In order to verify the correctness of the inventive method, test of direct current generator armature winding ground voltage and protection action test have been done.
One. the test of direct current generator armature winding ground voltage
Test is carried out on Z-H-29.5 DC generation unit.For simulation armature winding insulation descends, on a commutator segment of commutator, welded a resistance R n, the other end of resistance is connected with arbor, and arbor is by the brush reliable ground.
The ground voltage waveform that records under different resistance values as shown in Figure 4.
1.R nDuring=∞, the waveform that records such as Fig. 4 (a);
2.R nDuring=15M, the waveform that records such as Fig. 4 (b);
3.R nDuring=150M, the waveform that records such as Fig. 4 (c);
4, R n=0 o'clock, the waveform that records such as Fig. 4 (d).
Two. protection action test
Protection action test principle synoptic diagram as shown in Figure 5.
Convenience during for actual detected and unlikelyly influence the insulation against ground of direct current generator positive and negative electrode output terminal, we use resistance R 1, R 2, dividing potential drop is more stable to obtain (1/2)E fVoltage reference points, R simultaneously 3, R 4Value all bigger, so what influence the insulation against ground of motor positive and negative electrode output terminal is not had basically, detect the voltage waveform that obtains and also meet computational analysis, but should deduct in the calculation expression this moment (1/2)E f.
R in the protection action test nBe provided with and choose identical with the ground voltage test with resistance.The holding circuit principle of work is summarized as follows:
Under armature winding insulate normal situation, by expression formula (1) as can be known D point current potential be (1/2)E f, at R 1, R 2Under the effect, the current potential that A is ordered also is stabilized in (1/2)E fSo A point and D point are idiostatic, R 8, R 4Last no signal voltage, amplifier are output as zero, and protector can not move, when a certain winding insulation descends, and D point potential change, R 3And R 4On the signal voltage of an alternation is just arranged, pick up R 8On the alternating voltage signal, after amplifying, connect voltage table (making the resistance scale into) indication armature winding insulation situation, when signal is enough big, promotes relay BJ and implement to protect, and send armature winding earth fault signal.
R has been in this test nProtection action test for 1.5M and 150K has all obtained success, has realized preventive protection.
Be understood that adjusting enlargement factor can be when the single winding insulation of armature drops to a certain degree, send alerting signal or move in protection.More usable record instrument or microcomputer are drawn out the ground voltage waveform, for operation, maintainer's reference.
1. the inventive method is under all earth-free situation of direct current generator output terminal positive and negative electrode, and detection direct current generator armature winding ground voltage is implemented to protect.Therefore, be specially adapted to the protection of power station DC exciter.
2. the inventive method detects armature winding insulation situation, is not subjected to weather, the influence of changes in environmental conditions, only with winding between the difference of insulating resistance value relevant.No matter be at the bright weather of dry feelings---the armature winding insulation resistance up to hundreds of megaohms more than; still at moist rainy weather---the armature winding insulation resistance has only hundreds of kilo-ohm; as long as each winding insulation resistance unanimity, guard method of the present invention does not have output.
3. the inventive method ground voltage waveform has the good phase corresponding relation with insulation decline winding position, and this provides convenience to searching the insulation damage around group.
4. the inventive method is the operating online test method of motor, need not shutdown inspection.
5. because direct current generator is in operation, any one winding insulation worsens and can detect, and does not protect the dead band.This guard method all has protective effect for Dyn. winding and whole DC loop ground connection thereof.
6. the inventive method can be monitored in real time to motor, can do preventative detection protection before motor windings is damaged.
In a word, the inventive method is simple, carries out onlinely in that motor is in service, detects in real time, protection, need not shut down during inspection, and be a kind of, effectively, good method accurately, can be used for direct current generator.

Claims (1)

1. a direct current generator armature winding insulation detects and earthing protecting method, and it is characterized in that: adorn brush on motor shaft, draw arbor current potential D point, 2 of C, B are connected across the DC generator output voltage two ends; At the output terminal of direct current generator, get intermediate potential A point by divider resistance; With B point current potential is reference point, and the D point current potential of ordering with respect to B just often is like this (1/2)E f, A point current potential perseverance is (1/2)E f, when motor windings just often, do not have potential difference (PD) between A point and the D point; And when a certain winding insulation descended, D point current potential then changed, and becomes (1/2)E fAdd a pulsating volage, i.e. alternating voltage component, the degree of alternating voltage amplitude size and winding insulation decline is relevant, judges a certain winding insulation situation thus, reaches the purpose of preventative detection and protection.
CN98111264A 1998-04-23 1998-04-23 Method for insulation inspecting and ground protecting for windings of D. C. motor armature Expired - Fee Related CN1074131C (en)

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Application Number Priority Date Filing Date Title
CN98111264A CN1074131C (en) 1998-04-23 1998-04-23 Method for insulation inspecting and ground protecting for windings of D. C. motor armature

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CN1074131C CN1074131C (en) 2001-10-31

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101345458B (en) * 2008-05-22 2010-10-06 山东齐鲁电机制造有限公司 Full anti-dizzy VPI impregnation stator line stick and its industrial frequency overpressure-resistant detection method
CN106159902A (en) * 2015-03-28 2016-11-23 鞍钢股份有限公司 A kind of insulation detection device for direct current generator and method
CN106707119A (en) * 2016-12-23 2017-05-24 中国二冶集团有限公司 Insulation detection method for large- scale motor bearing
CN113419148A (en) * 2021-06-30 2021-09-21 深圳市准点仪器有限公司 Testing method for motor winding insulation

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101345458B (en) * 2008-05-22 2010-10-06 山东齐鲁电机制造有限公司 Full anti-dizzy VPI impregnation stator line stick and its industrial frequency overpressure-resistant detection method
CN106159902A (en) * 2015-03-28 2016-11-23 鞍钢股份有限公司 A kind of insulation detection device for direct current generator and method
CN106159902B (en) * 2015-03-28 2018-08-03 鞍钢股份有限公司 A kind of insulation detection device and method for direct current generator
CN106707119A (en) * 2016-12-23 2017-05-24 中国二冶集团有限公司 Insulation detection method for large- scale motor bearing
CN113419148A (en) * 2021-06-30 2021-09-21 深圳市准点仪器有限公司 Testing method for motor winding insulation

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