ASYNCHRONOUS MOTOR SQUIRREL CAGE: CONNECTIONS STARTING STAR Y DELTA

ANDRES CRUZ 45101371DIEGO A PEREZ L 45111700

FRANKLIN RODRIGUEZ 45101370DANIEL S RODRIGUEZ H 45121009

Submitted to:Ing. JOSE LUIS RUBIANO

LASALLE UNIVERSITY FACULTY OF ENGINEERING AUTOMATION

ELECTRO-MECHANICAL MACHINES BOGOTA D.C.

2015

ASYNCHRONOUS MOTOR SQUIRREL CAGE: CONNECTIONS STARTING STAR Y DELTA

I. INTRODUCTION An electrical motor has two states, boot and stable state, the boot is transitory, for the motor boot it’s necessary that the starting torque of the motor is greater than the resistive load torque, so it’s produced one deceleration spinning the engine at an increasing speed, having stable state when resistant and motor torque are equal. The boot process is accompanied by very high power consumption, which is the highest during engine operation. Usually, design rules and manufacturing of electric motors, set a three phase induction motor, which is fed to the nominal voltage and frequency must withstand for 15 seconds, without accelerating sharply, a starting torque equal to 1.6 times the nominal value. A kind of boot is the delta-star boot.

II. THEORETICAL FRAMEWORK

Star connection:

The star connection is denoted by the letter Y is achieved by joining the negative terminals of the three coils in a common point, neutral normally is grounded. The positive terminals are connected to the phases.

Delta connection:

This connection is made by attaching the end of a reel with the beginning of the next, to close the connection forming a triangle. It is a connection without neutral. The phases leave the vertices of the triangle.

In this type of connection, the phase voltages and line are equal, because the line leads out of the vertices of the triangle and the voltage between them is produced by the corresponding coil.

This boot is based on connecting the motor in star over a network where it needs to connect using delta. Thus during start the stator windings are at a voltage √3 less than the nominal

Taken from: http://www.cifp-mantenimiento.es/e-learning/index.php?id=15&id_sec=6

In the previous graphic we can see the behavior of the current and the torque for the direct boot in triangle and the star-delta boot.

III. MATERIALS Power Module DL1013M3 Squirrel cage motor DL1021 Operating manual feed module DL1013M3 Manual operation of the engine cage DL1021 Multimeter Ammeter

IV. METHODOLOGY

The methodology Followed in practice was first triangle connecting the engine DE LORENZO DL 1021 (Figure 1), then was provided with a voltage from 0 volts to 220 volts varying between intervals of 20% (Figure 2). Starting current of the engine in each interval was measured with the current clamps (Figure 3) and also the voltage between the terminals, all in original data were recorded in the respective tables was measured. The same procedure for connection and recording star was performed on the results obtained the respective tables. In a second part of the practice was supplied voltage to 340 volts for the starting current and voltage variables behave. Should be clear that some data starting currents are not reliable to obtain because the starting current was too large or the phenomenon happening in a short time the ammeter clamps which failed to grasp. With the data obtained we proceeded to analyze and finally to close up commercial practice.

Figure 1. Motor DE LORENZO DL 1021

Figure 2. DE LORENZO PANEL DL 1013 M3

Figure 3. The current clamps

V. TABLES AND ANALYSIS OF RESULTSWe proceed to perform measurements of voltage and current, between each of the lines and motor phases.

a. Connection in triangle.

Figure 1. Connection in triangle.

The position potentiometer range in values: 0, 20, 40, 60, 80, 100. Then the measurement is made between: U1 and U2, V1 and V2, and W1 and W2.The nominal current when have connection in triangle is in motor phases is for V, W and U, the same is 1.01A.

Table 1. Measurements in U1-U2V(v) I(A)

0 1,2 0,0820 52,07 3,9540 111,3 8,8860 165,3 11,980 217,6 1,9

100 0 0

0 2 4 6 8 10 12 140

50

100

150

200

250

1.2

52.07

111.3

165.3

217.6

Measurements in U1-U2

Current

Volta

ge

Table 2. Measurements in V1-V2V(v) I(A)

0 1.206 0.0820 51.97 4.0740 112.5 7.3760 164.5 13.7880 216.9 3.25

100 0 0

0 2 4 6 8 10 12 14 160

50

100

150

200

250

1.206

51.97

112.5

164.5

216.9

Measurements in V1-V2

Current

Volta

ge

Table 3. Measurements in W1-W2V(v) I(A)

0 1.2 0.0820 51.41 3.9540 111.3 9.1160 163 10.9280 214.3 14.84

100 0 0

0 2 4 6 8 10 12 14 160

50

100

150

200

250

f(x) = 14.5215401200611 x − 4.73558213407566R² = 0.986700991988205

Measurements in W1-W2

Current

Volta

ge

b. Connection in star.

Figure 2.Connection in star.

The nominal current when have connection in star is in motor phases is for V is 1.26A, for W is 1.03A and U is 1.91A.

Table 4. Measurements in UV(v) I(A)

0 1.317 0.0420 49.11 2.1640 112.3 4.5960 163.6 8.7380 216.8 8.06

100 268.6 0

0 1 2 3 4 5 6 7 8 9 100

50

100

150

200

250

f(x) = 22.1839737979038 x + 4.00577956908565R² = 0.92015783101011

Measurements in U

Current

Volta

ge

Table 5. Measurements in VV(v) I(A)

0 1.6 0.0520 50.17 2.1640 110.8 4.6360 164.5 7.1880 219.3 6.22

100 289.9 5.86

0 1 2 3 4 5 6 7 80

50

100

150

200

250

300

350

Measurements in V

Table 6. Measurements in WV(v) I(A)

0 1.193 0.0320 48.71 1.98

40 114.8 2.3860 165.2 4.3480 219.2 5.64

100 271.8 1.05

0 1 2 3 4 5 60

50

100

150

200

250

300

f(x) = 22.9741467010689 x + 77.7736096449196R² = 0.218391852253977

Measurements in W

Current

Volta

ge

VI. CONCLUSIONS It is important to keep in mind in this practice, that low speed in the

motor could overheat the inductors causing a short-circuit, having temperatures over Curie's.

The machines that transform electrical energy in mechanical are known as motors.

Alternating current motors are the most common in the industries and factories.

VII. REFERENCES

http://www.motortico.com/biblioteca/MotorTico/2013%20NOV%20-%20Corriente%20de%20Arranque%20en%20Motores%20Electricos.pdf

http://educativa.catedu.es/44700165/aula/archivos/repositorio/3000/3020/html/132_conexin_en_estrella.html

http://educativa.catedu.es/44700165/aula/archivos/repositorio/3000/3020/html/133_conexin_en_tringulo.html