REPORT
On laboratory work №3
On the discipline “Electric machines”
Theme: “Research of asynchronous electric motor with short-circuited rotor”
Specialty: 5B071800- Electrical Power Engineering
Done by: Shaimuradov E. Group: EPEe-15-10
Checked by: Abdullaev Z.M.
_________ ___________ “___” __________ 2017
(score) (signature)
Laboratory work № 3.Research of asynchronous electric motor with short-circuited rotor
Objectiveof the work: research of working properties of the asynchronous electric motor by taking the corresponding experimental characteristics.
Program of work
1. To study the circuits for the investigation of an induction motor with a squirrel cage rotor (hereinafter referred to as AD)
2. Investigate the engine in short circuit mode
3. Investigate the engine in idling mode
4. Remove the engine performance by the direct load method
5. According to experiments idling and short circuit, calculate the engine parameters, build a replacement circuit
6. Carry out the processing of the experimental data, compile a report and make an opinion on the work.
List of used equipment
In laboratory work are used the following modules:
· power module stand (ICS);
· module power (MP);
· the power meter module (MIM);
· module additional resistances №l (MdC1);
· module additional resistances №2 (MdC2);
· power module (SM);
· module of the frequency converter (inverter);
· Module measuring (MI).);
1. The experience of a short-circuit in an asynchronous motor
The short-circuit test is performed with a restrained (rotor-locked) reduced voltage, at which the stator current is approximately equal to the rated current of the stator I1к 
I1н. The circuit for carrying out the short-circuit test is shown in Figure 1.
Figure 1— Scheme for conducting short-circuit and idle tests
Table 1
| Experimental data | Calculation data | ||||||||||
| U1fk | I1fk | P1fk | cosϕ1fk | P1k | ΔPel1 | ΔPst | Pemk | Memk | zk | rk | xk |
| V | A | W | W | W | W | W | Nm | Ohm | Ohm | Ohm | |
| 166.2 | 1.26 | 154.96 | 0.74 | 464.89 | 90.49 | 2.71 | 371.69 | - |
Calculation data
Three-phase active power at short-circuit mode
Electric losses in the stator circuit
ΔPel1=m1·I1k2·r1=3·1.262·19=90.49 W
Losses in steel
Electromagnetic power at short-circuit mode
Electromagnetic moment at short-circuit mode
Multiplicity of starting current
2. Experience of idling mode of an asynchronous motor
The study of the engine in idling mode is carried out for a single voltage value equal to the nominal value, and it makes it possible to estimate the value of the no-load current, as well as the loss in steel at a nominal voltage.
The scheme of the idling test is shown in Fig. 1.
The experiment is carried out in the following sequence:
-include the QF1 and QF2 circuit breakers corresponding to the MPS and MP;
- switchSAl MdC1 set from position «
» to position «0», the voltage takes a value equal to the nominal, the induction motor starts.
Table2
| Experimental data | Calculation data | |||||||
| U1fn | I10 | P1f | ω | P10 | cosϕ10 | ΔPel1 | ΔPst | I10* |
| V | A | W | rad/s | W | W | W | ||
| 1.324 | 96.78 | 143.4 | 290.34 | 0.186 | 96.33 | 179.7 | 0.97 |
Calculation data
Power factor
Active power of three phase
Losses in steel at a rated voltage
Losses in steel at U=393 V
Value of the idling current in relative units
3. Operation characteristics
Scheme for deactivation is shown in Figure 2.
Figure 2 — Circuit for deactivating the performance of an induction motor
The experiment is carried out in the following sequence:
-turn on the automatic machines and QF2 modules of MPS and MP;
-adjust the frequency converter (Appendix Г);
-setting the SAl of the inverter module to the end position to start the induction motor, set the output voltage frequency to 50 Hz (RP1);
-switch SA1 MDS 2, decreasing the resistance, increase the DCM load until the current of the GPT armature reaches the nominal value (1.3A). (SA1 to "0" not output!) Experienced data from the side, both the asynchronous motor, and the generator side, enter in Table 3 and 4.
Table 3
| From the side of AEM | ||||||||||||||
| Exp. data | Calculation data | |||||||||||||
| I1f | P1 | n | cosϕ1 | U1 | ΔPel1 | ΔPst | Pem | s | ΔPel2 | ΔPmch | ∑ΔP | P2 | Mem | η |
| A | W | rpm | V | W | W | W | W | W | W | W | Nm | % | ||
| 1.1 | 0,06 | 68.97 | 4.75 | 0.28 | 0,0134 | 3.75m | 84.72 | -10.7 | 1.78m | -14 | ||||
| 1.1 | 192.4 | 0,15 | 68.97 | 4.75 | 118.68 | 0,07 | 8.3 | 93.02 | 99.38 | 0.75 | 51.65 | |||
| 1.1 | 203.5 | 0,162 | 68.97 | 4.75 | 129.78 | 0,076 | 9.86 | 94.58 | 108.92 | 0.83 | 53.52 | |||
| 1.1 | 214.6 | 0,17 | 68.97 | 4.75 | 140.88 | 0,083 | 11.69 | 96.32 | 118.28 | 0.9 | 55.12 | |||
| 1.2 | 229.4 | 0,17 | 82.08 | 4.75 | 142.57 | 0,093 | 13.26 | 97.92 | 131.48 | 0.91 | 57.31 | |||
| 1.2 | 251.6 | 0,184 | 82.08 | 4.75 | 164.77 | 0,1 | 16.48 | 101.12 | 150.48 | 1.05 | 59.81 |
Table 4
| From the side of the DCG | |||||||
| Exp.data | Calculation data | ||||||
| Ian | Uan | Cm | Mem | Ian0 | M0 | M2 | P2 |
| A | V | Nm | A | Nm | Nm | W | |
| 183.7 | 1,35 | 0,2100 | 0,283 | 0,283 | 43,84 | ||
| 0.82 | 144.1 | 1,32 | 1,082 | 0,2000 | 0,264 | 1,346 | 196,38 |
| 0.91 | 139.4 | 1,31 | 1,192 | 0,1980 | 0,259 | 1,451 | 210,5 |
| 1.02 | 134.1 | 1,30 | 1,326 | 0,1950 | 0,253 | 1,579 | 227,2 |
| 1.14 | 126.1 | 1,29 | 1,47 | 0,1910 | 0,246 | 1,716 | 244,27 |
| 1.31 | 116.5 | 1,28 | 1,68 | 0,1875 | 0,240 | 1,92 | 268,88 |
4. Calculation of the parameters of an induction motor. Construction of a substitution scheme. The tests of idling and short circuit make it possible to calculate the parameters of an asynchronous motor and to construct a replacement circuit.
Idling mode
Active resistance of magnetization circuit, Ohm
Total resistance of the magnetization circuit, Ohm
Inductive resistance of the magnetization circuit
From the short-circuit mode
Total resistance, Ohm
Active resistance, Ohm
Inductive resistance of the magnetization circuit
Figure 3— T-shaped replacement scheme
Figure 4
Figure 5
Figure 6
Figure 7
Conclusion: In this laboratory work we have studied the asynchronous electric motor with short-circuited rotor in idling mode, in short-circuit mode and take the operational characteristics. When three-phase winding of the stator is switched on, an alternating current is generated in the working air gap by a rotating magnetic field. The rotating field of the stator intersect the conductors of the rotor winding and induces EMF in them. The rotor winding is closed the electric circuit and therefore a current. The latter generates a magnetic field in the rotor winding which interacts with the rotating field of the stator, carrying the rotor in the direction of rotation of the stator field. In this case, the rotational speed of the rotor n is not equal to the rotation frequency of the field and will never be able to equalize with it. The equality of frequencies of rotation of the rotor and the stator field would be to their mutual (in relation to each other) quiescence, and hence the impossibility of any EMF in the rotor winding (for winding of the rotor do not overlap the field of the stator). So, this is called an asynchronous alternating current machine, the rotor of which rotates asynchronously relative to the rotating magnetic field of the stator.
List of references
1 Копылов И.П. Электрические машины.-М.: Высшая школа, Логос, 2000. -607 с.
2Брускин Д.Э., Зорохович А.Е., Хвостов В.С. Электрические машины. Ч. 1,2. -М.: Высшая школа, 1987.
3 Копылов И.П. Электрические машины.-М.: Энергоатомиздат, 1986.-360 с.
4Вольдек А.И. Электрические машины.-Л.: Энергия, 1978.-832 с.
5 Костенко М.П., Пиотровский Л.М. Электрические машины. Ч.2 Машины переменного тока.- Л.: Энергия, 1973. - 412 с.