CN105116332A - Test method for motor under high-temperature and low-pressure environment - Google Patents

Abstract

The invention relates to a test method of a motor under a high-temperature and low-pressure environment and belongs to the technical field of motor characteristic testing under the high-temperature and low-pressure environment. The test method includes the following steps that: a measured motor and a standby motor are arranged in a low-pressure experimental box; the measured motor works in a motor state, and the standby motor works in a generator state; the stator current of the measured motor is gradually decreased to 0.5-times rated current from 1.5-times rated current; the stray loss of the measured motor working in the motor state is P<Ms>; the measured motor works in a generator state, and the standby motor works in a motor state; the stator current of the standby motor is gradually decreased to 0.5-times rated current from 1.5-times rated current; the stray loss of the measured motor working in the generator state is P<Gs>; and the average value P<->s of the stray loss of the load of the measured motor can be obtained based on the above measured parameters and calculation results. With the test method of the invention adopted, the parameters of the motor can be detected under the high-temperature and low-pressure environment. According to the test method, and the motor can be tested under the high-temperature and low-pressure environment through adopting a double-motor back-to-back test method, and the loss values of various parameters of the motor can be calculated accurately.

Description

The method of testing of motor under a kind of high-temperature low-pressure environment

Technical field

The invention belongs to the technical field of motor characteristic test under high-temperature low-pressure environment.

Background technology

Along with the continuous exploration of the external space field of the mankind, as the motor of execution requisite in Aero-Space and functional part, can more and more be applied in various extreme environment, such as high-temperature low-pressure environment, must test accordingly the performance of motor before motor uses, to verify that can it normally be operated in this extreme environment of high-temperature low-pressure, and performance meets design requirement.But the method for testing of existing motor is applicable to normal temperature and pressure situation more, the test of motor in high-temperature low-pressure situation can not be met.

Summary of the invention

The object of this invention is to provide the method for testing of motor under a kind of high-temperature low-pressure environment, is that the method for testing in order to solve existing motor is applicable to normal temperature and pressure situation more, can not meet the problem of the test of motor in high-temperature low-pressure situation.

Described object is realized by following scheme: the method for testing of motor under described a kind of high-temperature low-pressure environment, and its method step is:

Step one: select one identical with by measured motor 1 specification, or with by measured motor 1, there is identical synchronous rotational speed but power is greater than by the motor of other specification of measured motor 1 as accompanying and serving motor 2; Be in transmission connection by the output revolving shaft of measured motor 1 by shaft coupling 3 and the output revolving shaft of accompanying and serving motor 2, then high/low temperature low atmospheric pressure test case 4 internal fixtion is put into good, probe temperature in high/low temperature low atmospheric pressure test case 4 is arranged between 100 DEG C ~ 200 DEG C, atmospheric pressure value is arranged on and is less than 0.01Mpa, makes it close to the force value of the vacuum environment of the outer space;

Step 2: make to be operated in electric motor state by measured motor 1, accompany and serve motor 2 and be operated in Generator Status; First driver 5 drives by measured motor 1 operation, makes to be worked under rated frequency and rated voltage by measured motor 1; Second driver 6 driving is accompanied and served motor 2 and is worked, and makes to accompany and serve motor 2 relative to being turned to upper applying reverse drive by measured motor 1; The second driver 6 is regulated to make in nominal load situation, to be run to steady state (SS) by measured motor 1;

Step 3: by second driver 6 regulate accompany and serve motor 2, make to be changed to 0.5 times of rated current by the stator current of measured motor 1 gradually from 1.5 times of rated current, read in this course as motor running by the triple-phase line electric current I of measured motor 1 _m1, power input P _m1, stator winding resistance value R _m1, need in process of the test to keep being always ratings by the frequency and voltage of measured motor 1; Read work is in the triple-phase line electric current I of accompanying and serving motor 2 of Generator Status simultaneously _g1, output power P _g2, stator winding resistance value R _g1; The experimental data utilizing above-mentioned measurement to obtain also just can calculate by measured motor 1 and the stator copper loss of accompanying and serving motor 2 in conjunction with following formula:

$P_{Mcu1}=1.5I_{M1}{R}_{M1}^2;P_{Gcu1}=1.5I_{G1}{R}_{G1}^2;$

Step 4: the method measuring rotor one phase current with tong-type ammeter is determined by measured motor 1 and the revolutional slip s accompanying and serving motor 2 _mand s _g, adopt the method mainly to consider that motor measurement environment constrains other in order to determine the use of the experimental facilities of motor slip ratio; First the number of oscillations N of record current list index _m, N _g, and with stopwatch record N _m, N _gthe time t of secondary swing _m, t _g; Then following formula is used to determine by measured motor 1 and the revolutional slip s accompanying and serving motor 2 _mand s _g:

$s_M=\frac{N_M}{2t_M{f}_M}\&times;100\%;s_G=\frac{N_G}{2t_G{f}_G}\&times;100\%,$

In formula, f _mfor by the rated frequency of measured motor 1; f _gfor accompanying and serving the frequency of motor 2, this frequency is less than rated frequency;

Step 5: be operated in electric motor state by the rotor copper loss P of measured motor 1 _mcu2: P _mcu2=s _m(P _m1-P _mcu1-P _fe); Be operated in the rotor copper loss P accompanying and serving motor 2 of Generator Status _gcu2: P _gcu2=s _g(P _g2-P _gcu1-P _fe);

Step 6: be operated under electric motor state by the stray loss P of measured motor 1 _ms: P _ms=∑ P _sp _mcu2/ (P _gcu2+ P _mcu2), in formula, ∑ P _sfor by measured motor 1 and total stray loss of accompanying and serving motor 2, and ∑ P _scomputing formula be:

∑P _s＝P _M1-P _G2-P _Mcu1-P _Gcu1-P _Mcu2-P _Gcu2-P _fe-P′ _fe-P _Δ-P′ _Δ；

Step 7: and motor 2 will be accompanied and served to shut down work by measured motor 1; Make to be operated in Generator Status by measured motor 1, accompany and serve motor 2 and be operated in electric motor state; Second driver 6 drives and accompanies and serves motor 2 operation, makes to accompany and serve motor 2 and works under rated voltage He under being greater than rated frequency condition; First driver 5 drives and is worked by measured motor 1, makes to be turned to upper applying reverse drive by measured motor 1 relative to accompanying and serving motor 2; The load value regulating the first driver 5 to make to accompany and serve motor 2 be worth equal situation by measured motor 1 nominal load under run to steady state (SS);

Step 8: regulated by measured motor 1 by the first driver 5, is made the stator current of accompanying and serving motor 2 change to 0.5 times of rated current gradually from 1.5 times of rated current, reads the triple-phase line electric current I of accompanying and serving motor 2 as motor running in this course _m1, power input P _m1, stator winding resistance value R _m1, need in process of the test to keep being always ratings by the frequency and voltage of measured motor 1; Simultaneously read work at Generator Status by the triple-phase line electric current I of measured motor 1 _g1, output power P _g2, stator winding resistance value R _g1; The experimental data utilizing above-mentioned measurement to obtain also just can calculate by measured motor 1 and the stator copper loss of accompanying and serving motor 2 in conjunction with following formula:

$P_{Mcu1}=1.5I_{M1}{R}_{M1}^2;P_{Gcu1}=1.5I_{G1}{R}_{G1}^2;$

Step 9: the method measuring rotor one phase current with tong-type ammeter is determined by measured motor 1 and the revolutional slip s accompanying and serving motor 2 _gand s _m, adopt the method mainly to consider that motor measurement environment constrains other in order to determine the use of the experimental facilities of motor slip ratio; First the number of oscillations N of record current list index _g, N _m, and with stopwatch record N _g, N _mthe time t of secondary swing _g, t _m; Then following formula is used to determine by measured motor 1 and the revolutional slip s accompanying and serving motor 2 _gand s _m:

$s_G=\frac{N_G}{2t_G{f}_G}\&times;100\%;s_M=\frac{N_M}{2t_M{f}_M}\&times;100\%,$

In formula, f _gfor by the rated frequency of measured motor 1; f _mfor accompanying and serving the frequency of motor 2, this frequency is greater than by the rated frequency of measured motor 1;

Step 10: the rotor copper loss P accompanying and serving motor 2 being operated in electric motor state _mcu2: P _mcu2=s _m(P _m1-P _mcu1-P ' _fe); Be operated in Generator Status by the rotor copper loss P of measured motor 1 _gcu2: P _gcu2=s _g(P _g2-P _gcu1-P _fe);

Step 11: be operated under Generator Status by the stray loss P of measured motor 1 _gsfor: P _gs=∑ P _sp _gcu2/ (P _gcu2+ P _mcu2), in formula, ∑ P _sfor by measured motor 1 and total stray loss of accompanying and serving motor 2, but now P _gcu2for by measured motor 1 rotor copper loss, P _mcu2for accompanying and serving motor 2 rotor copper loss, and ∑ P _scomputing formula be:

∑P _s＝P _M1-P _G2-P _Mcu1-P _Gcu1-P _Mcu2-P _Gcu2-P _fe-P′ _fe-P _Δ-P′ _Δ；

Step 12: ask for by the mean value of measured motor 1 load stray loss in conjunction with the measurement parameter in above-mentioned steps and calculating knot for: by the approximate average of measured motor 1 at motor and Generator Status rotor electric current for: in formula, I ₁for during load test by the stator current of measured motor 1 in above-mentioned steps, namely by the stator current of measured motor 1 under electric motor state and Generator Status, I ₀for during by measured motor 1 no-load test, the stator current that rated voltage is corresponding.

Under the inventive method can carry out high-temperature low-pressure environment to motor, each parameter is measured, the motor under this environment tested by employing two-shipper to the method for dragging, doing so avoids the shortcoming of some equipment cisco unity malfunction under this environment, and still can ensure to design needs in measuring accuracy, and every loss value of motor can accurately be calculated.

Accompanying drawing explanation

Fig. 1 is the structural representation of the device that the inventive method relates to.

Embodiment

Embodiment one: shown in composition graphs 1, illustrates the technical scheme of this embodiment, and its method step is:

Step one: select one identical with by measured motor 1 specification, or with by measured motor 1, there is identical synchronous rotational speed but power is greater than by the motor of other specification of measured motor 1 as accompanying and serving motor 2; Be in transmission connection by the output revolving shaft of measured motor 1 by shaft coupling 3 and the output revolving shaft of accompanying and serving motor 2, then high/low temperature low atmospheric pressure test case 4 internal fixtion is put into good, probe temperature in high/low temperature low atmospheric pressure test case 4 is arranged between 100 DEG C ~ 200 DEG C, atmospheric pressure value is arranged on and is less than 0.01Mpa, makes it close to the force value of the vacuum environment of the outer space;

Step 2: make to be operated in electric motor state by measured motor 1, accompany and serve motor 2 and be operated in Generator Status; First driver 5 drives by measured motor 1 operation, makes to be worked under rated frequency and rated voltage by measured motor 1; Second driver 6 driving is accompanied and served motor 2 and is worked, and makes to accompany and serve motor 2 relative to being turned to upper applying reverse drive by measured motor 1; The second driver 6 is regulated to make in nominal load situation, to be run to steady state (SS) by measured motor 1;

Step 3: by second driver 6 regulate accompany and serve motor 2, make to be changed to 0.5 times of rated current by the stator current of measured motor 1 gradually from 1.5 times of rated current, read in this course as motor running by the triple-phase line electric current I of measured motor 1 _m1, power input P _m1, stator winding resistance value R _m1, need in process of the test to keep being always ratings by the frequency and voltage of measured motor 1; Read work is in the triple-phase line electric current I of accompanying and serving motor 2 of Generator Status simultaneously _g1, output power P _g2, stator winding resistance value R _g1; The experimental data utilizing above-mentioned measurement to obtain also just can calculate by measured motor 1 and the stator copper loss of accompanying and serving motor 2 in conjunction with following formula:

$P_{Mcu1}=1.5I_{M1}{R}_{M1}^2;P_{Gcu1}=1.5I_{G1}{R}_{G1}^2;$

Step 4: the method measuring rotor one phase current with tong-type ammeter is determined by measured motor 1 and the revolutional slip s accompanying and serving motor 2 _mand s _g, adopt the method mainly to consider that motor measurement environment constrains other in order to determine the use of the experimental facilities of motor slip ratio; First the number of oscillations N of record current list index _m, N _g, and with stopwatch record N _m, N _gthe time t of secondary swing _m, t _g; Then following formula is used to determine by measured motor 1 and the revolutional slip s accompanying and serving motor 2 _mand s _g:

$s_M=\frac{N_M}{2t_M{f}_M}\&times;100\%;s_G=\frac{N_G}{2t_G{f}_G}\&times;100\%,$

In formula, f _mfor by the rated frequency of measured motor 1; f _gfor accompanying and serving the frequency of motor 2, this frequency is less than rated frequency;

Step 5: be operated in electric motor state by the rotor copper loss P of measured motor 1 _mcu2: P _mcu2=s _m(P _m1-P _mcu1-P _fe); Be operated in the rotor copper loss P accompanying and serving motor 2 of Generator Status _gcu2: P _gcu2=s _g(P _g2-P _gcu1-P ' _fe);

Step 6: be operated under electric motor state by the stray loss P of measured motor 1 _ms: P _ms=∑ P _sp _mcu2/ (P _gcu2+ P _mcu2), in formula, ∑ P _sfor by measured motor 1 and total stray loss of accompanying and serving motor 2, and ∑ P _scomputing formula be:

∑P _s＝P _M1-P _G2-P _Mcu1-P _Gcu1-P _Mcu2-P _Gcu2-P _fe-P′ _fe-P _Δ-P′ _Δ；

Step 7: and motor 2 will be accompanied and served to shut down work by measured motor 1; Make to be operated in Generator Status by measured motor 1, accompany and serve motor 2 and be operated in electric motor state; Second driver 6 drives and accompanies and serves motor 2 operation, makes to accompany and serve motor 2 and works under rated voltage He under being greater than rated frequency condition; First driver 5 drives and is worked by measured motor 1, makes to be turned to upper applying reverse drive by measured motor 1 relative to accompanying and serving motor 2; The load value regulating the first driver 5 to make to accompany and serve motor 2 be worth equal situation by measured motor 1 nominal load under run to steady state (SS);

Step 8: regulated by measured motor 1 by the first driver 5, is made the stator current of accompanying and serving motor 2 change to 0.5 times of rated current gradually from 1.5 times of rated current, reads the triple-phase line electric current I of accompanying and serving motor 2 as motor running in this course _m1, power input P _m1, stator winding resistance value R _m1, need in process of the test to keep being always ratings by the frequency and voltage of measured motor 1; Simultaneously read work at Generator Status by the triple-phase line electric current I of measured motor 1 _g1, output power P _g2, stator winding resistance value R _g1; The experimental data utilizing above-mentioned measurement to obtain also just can calculate by measured motor 1 and the stator copper loss of accompanying and serving motor 2 in conjunction with following formula:

$P_{Mcu1}=1.5I_{M1}{R}_{M1}^2;P_{Gcu1}=1.5I_{G1}{R}_{G1}^2;$

Step 9: the method measuring rotor one phase current with tong-type ammeter is determined by measured motor 1 and the revolutional slip s accompanying and serving motor 2 _gand s _m, adopt the method mainly to consider that motor measurement environment constrains other in order to determine the use of the experimental facilities of motor slip ratio; First the number of oscillations N of record current list index _g, N _m, and with stopwatch record N _g, N _mthe time t of secondary swing _g, t _m; Then following formula is used to determine by measured motor 1 and the revolutional slip s accompanying and serving motor 2 _gand s _m:

$s_G=\frac{N_G}{2t_G{f}_G}\&times;100\%;s_M=\frac{N_M}{2t_M{f}_M}\&times;100\%,$

In formula, f _gfor by the rated frequency of measured motor 1; f _mfor accompanying and serving the frequency of motor 2, this frequency is greater than by the rated frequency of measured motor 1;

Step 10: the rotor copper loss P accompanying and serving motor 2 being operated in electric motor state _mcu2: P _mcu2=s _m(P _m1-P _mcu1-P ' _fe); Be operated in Generator Status by the rotor copper loss P of measured motor 1 _gcu2: P _gcu2=s _g(P _g2-P _gcu1-P ' _fe);

Step 11: be operated under Generator Status by the stray loss P of measured motor 1 _gsfor: P _gs=∑ P _sp _gcu2/ (P _gcu2+ P _mcu2), in formula, ∑ P _sfor by measured motor 1 and total stray loss of accompanying and serving motor 2, but now P _gcu2for by measured motor 1 rotor copper loss, P _mcu2for accompanying and serving motor 2 rotor copper loss, and ∑ P _scomputing formula be:

∑P _s＝P _M1-P _G2-P _Mcu1-P _Gcu1-P _Mcu2-P _Gcu2-P _fe-P′ _fe-P _Δ-P′ _Δ；

Step 12: ask for by the mean value of measured motor 1 load stray loss in conjunction with the measurement parameter in above-mentioned steps and calculating knot for: by the approximate average of measured motor 1 at motor and Generator Status rotor electric current for: in formula, I ₁for during load test by the stator current of measured motor 1 in above-mentioned steps, namely by the stator current of measured motor 1 under electric motor state and Generator Status, I ₀for during by measured motor 1 no-load test, the stator current that rated voltage is corresponding.

Principle of work: the high-temperature low-pressure test environment needed for experiment can directly utilize high/low temperature low atmospheric pressure test case to complete, only need to be put into this experimental box by measured motor together with measuring equipment, due to some measuring equipment cisco unity malfunction under high-temperature low-pressure environment, the present invention proposes to utilize two-shipper to measure by the performance parameter of measured motor the method for holder for this reason, namely select identical with testing of electric motors specification, or with by measured motor, be there is identical synchronous rotational speed, power is greater than by the motor of other specifications of measured motor as accompanying examination motor.

First to by measured motor and accompany examination motor carry out no-load test to determine its iron loss and mechanical loss.Its method of testing is by by measured motor with accompany examination motor to put into high/low temperature low pressure test (LPT) case respectively and fixing, then motor no-load running under rated voltage and rated frequency is respectively tried by measured motor with accompanying, reach mechanical loss stable after, by controlling the voltage be applied in motor stator winding, complete no-load test, and calculate required by the core loss of measured motor and mechanical loss.For determining the unloaded stator copper loss of motor, the resistance of motor stator winding while each reading measurement parameter, need be read.

Adopt in high-temperature low-pressure situation, the shaft coupling connection that still can normally work is by measured motor and accompany examination motor, then by after good for connection by measured motor and accompany examination motor together to put into high/low temperature low atmospheric pressure test case, be connected by measured motor with the AC power that can export rated frequency, accompany examination motor to be connected with the AC power of frequency-adjustable.Again by the equipment of some necessity with try after motor connects and get well by measured motor and accompanying, the measurement just can be correlated with to it.

First no-load test is carried out to motor, in order to determine by measured motor and core loss and the mechanical loss of accompanying examination motor.Allow by measured motor in measuring process and accompany the no-load running under rated voltage and rated frequency of examination motor to stablize to mechanical loss, regulating the voltage be applied on stator winding, and measure required motor performance parameter in this course, complete the no-load test of motor.No-load test is mainly determined by the core loss of measured motor and mechanical loss P _feand P _Δand accompany core loss and the mechanical loss of examination motor with P ' _Δ.Owing to being operated in the motor of high-temperature low-pressure state, the resistance of its stator winding can be subject to the joint effect of temperature and pressure, thus the formula usually calculating resistance again and inapplicable, therefore must read at every turn survey parameter while read this value.

The method of two-shipper to holder is made up of two processes, for avoiding measurement result to occur larger error, need calibrate measuring instrumentation.

Claims (1)

1. the method for testing of motor under high-temperature low-pressure environment, is characterized in that its method step is:

Step one: select one identical with by measured motor (1) specification, or with by measured motor (1), there is identical synchronous rotational speed but power is greater than by the motor of other specification of measured motor (1) as accompanying and serving motor (2); Be in transmission connection by the output revolving shaft of measured motor (1) by shaft coupling (3) and the output revolving shaft of accompanying and serving motor (2), probe temperature in high/low temperature low atmospheric pressure test case (4) is arranged between 100 DEG C ~ 200 DEG C, atmospheric pressure value is arranged on and is less than 0.01Mpa, makes it close to the force value of the vacuum environment of the outer space;

Step 2: make to be operated in electric motor state by measured motor (1), accompany and serve motor (2) and be operated in Generator Status; First driver (5) drives by measured motor (1) operation, makes to be worked under rated frequency and rated voltage by measured motor (1); Second driver (6) drives accompanies and serves motor (2) work, makes to accompany and serve motor (2) and turns to upper applying reverse drive relative to by measured motor (1); The second driver (6) is regulated to make in nominal load situation, to be run to steady state (SS) by measured motor (1);

Step 3: regulated by the second driver (6) and accompany and serve motor (2), make to be changed to 0.5 times of rated current by the stator current of measured motor (1) gradually from 1.5 times of rated current, read in this course as motor running by the triple-phase line electric current I of measured motor (1) _m1, power input P _m1, stator winding resistance value R _m1, need in process of the test to keep being always ratings by the frequency and voltage of measured motor (1); Read work is in the triple-phase line electric current I of accompanying and serving motor (2) of Generator Status simultaneously _g1, output power P _g2, stator winding resistance value R _g1; The experimental data utilizing above-mentioned measurement to obtain also just can calculate by measured motor (1) and the stator copper loss of accompanying and serving motor (2) in conjunction with following formula:

$P_{Mcu1}=1.5I_{M1}{R}_{M1}^2;P_{Gcu1}=1.5I_{G1}{R}_{G1}^2;$

Step 4: the method measuring rotor one phase current with tong-type ammeter is determined by measured motor (1) and the revolutional slip s accompanying and serving motor (2) _mand s _g, adopt the method mainly to consider that motor measurement environment constrains other in order to determine the use of the experimental facilities of motor slip ratio; First the number of oscillations N of record current list index _m, N _g, and with stopwatch record N _m, N _gthe time t of secondary swing _m, t _g; Then following formula is used to determine by measured motor (1) and the revolutional slip s accompanying and serving motor (2) _mand s _g:

$s_M=\frac{N_M}{2t_M{f}_M}\&times;100\%;$ $s_G=\frac{N_G}{2t_G{f}_G}\&times;100\%,$

In formula, f _mfor by the rated frequency of measured motor (1); f _gfor accompanying and serving the frequency of motor (2), this frequency is less than rated frequency;

Step 5: be operated in electric motor state by the rotor copper loss P of measured motor (1) _mcu2: P _mcu2=s _m(P _m1-P _mcu1-P _fe); Be operated in the rotor copper loss P accompanying and serving motor (2) of Generator Status _gcu2: P _gcu2=s _g(P _g2-P _gcu1-P` _fe);

Step 6: be operated under electric motor state by the stray loss P of measured motor (1) _ms: P _ms=∑ P _sp _mcu2/ (P _gcu2+ P _mcu2), in formula, ∑ P _sfor by measured motor (1) and total stray loss of accompanying and serving motor (2), and ∑ P _scomputing formula be:

∑P _s＝P _M1-P _G2-P _Mcu1-P _Gcu1-P _Mcu2-P _Gcu2-P _fe-P` <sub>fe</sub>-P <sub>Δ</sub>-P` _Δ；

Step 7: and motor (2) will be accompanied and served to shut down work by measured motor (1); Make to be operated in Generator Status by measured motor (1), accompany and serve motor (2) and be operated in electric motor state; Second driver (6) drives and accompanies and serves motor (2) operation, makes to accompany and serve motor (2) and works under rated voltage He under being greater than rated frequency condition; First driver (5) drives by measured motor (1) work, makes to be turned to upper applying reverse drive by measured motor (1) relative to accompanying and serving motor (2); The load value regulating the first driver (5) to make to accompany and serve motor (2) be worth equal situation by measured motor (1) nominal load under run to steady state (SS);

Step 8: regulated by measured motor (1) by the first driver (5), make the stator current of accompanying and serving motor (2) change to 0.5 times of rated current gradually from 1.5 times of rated current, read the triple-phase line electric current I of accompanying and serving motor (2) as motor running in this course _m1, power input P _m1, stator winding resistance value R _m1, need in process of the test to keep being always ratings by the frequency and voltage of measured motor (1); Simultaneously read work at Generator Status by the triple-phase line electric current I of measured motor (1) _g1, output power P _g2, stator winding resistance value R _g1; The experimental data utilizing above-mentioned measurement to obtain also just can calculate by measured motor (1) and the stator copper loss of accompanying and serving motor (2) in conjunction with following formula:

$P_{Mcu1}=1.5I_{M1}{R}_{M1}^2;$ $P_{Gcu1}=1.5I_{G1}{R}_{G1}^2;$

Step 9: the method measuring rotor one phase current with tong-type ammeter is determined by measured motor (1) and the revolutional slip s accompanying and serving motor (2) _gand s _m, adopt the method mainly to consider that motor measurement environment constrains other in order to determine the use of the experimental facilities of motor slip ratio; First the number of oscillations N of record current list index _g, N _m, and with stopwatch record N _g, N _mthe time t of secondary swing _g, t _m; Then following formula is used to determine by measured motor (1) and the revolutional slip s accompanying and serving motor (2) _gand s _m:

$s_G=\frac{N_G}{2t_G{f}_G}\&times;100\%;$ $s_M=\frac{N_M}{2t_M{f}_M}\&times;100\%,$

In formula, f _gfor by the rated frequency of measured motor (1); f _mfor accompanying and serving the frequency of motor (2), this frequency is greater than by the rated frequency of measured motor (1);

Step 10: the rotor copper loss P accompanying and serving motor (2) being operated in electric motor state _mcu2: P _mcu2=s _m(P _m1-P _mcu1-P` _fe); Be operated in Generator Status by the rotor copper loss P of measured motor (1) _gcu2: P _gcu2=s _g(P _g2-P _gcu1-P _fe);

Step 11: be operated under Generator Status by the stray loss P of measured motor (1) _gsfor: P _gs=∑ P _sp _gcu2/ (P _gcu2+ P _mcu2), in formula, ∑ P _sfor by measured motor (1) and total stray loss of accompanying and serving motor (2), but now P _gcu2for by measured motor (1) rotor copper loss, P _mcu2for accompanying and serving motor (2) rotor copper loss, and ∑ P _scomputing formula be:

∑P _s＝P _M1-P _G2-P _Mcu1-P _Gcu1-P _Mcu2-P _Gcu2-P _fe-P` <sub>fe</sub>-P <sub>Δ</sub>-P` _Δ；

Step 12: ask for by the mean value of measured motor (1) load stray loss in conjunction with the measurement parameter in above-mentioned steps and calculating knot for: by the approximate average of measured motor (1) at motor and Generator Status rotor electric current for: in formula, I ₁for during load test by measured motor (1) stator current in above-mentioned steps, namely by measured motor (1) stator current under electric motor state and Generator Status, I ₀for during by measured motor (1) no-load test, the stator current that rated voltage is corresponding.