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CALCULATION OF MECHANICAL CHARACTERISTICS OF INDUCTION MOTOR USED IN TEXTILE MACHINERY..,
Pirmatov Nurali Berdiyorovich, doctorof Engineering, Professor, Head of the Department of Electric Machines at Tashkent State Technical University Panoyev Abdullo Tilloyevich, Ph D., candidate, (person working for doctor's degree) of the Department Electric Power Industry at Bukhara Engineering-Technological Institute, Bukhara City, K. Murtazayev Str., house 15, E-mail: panoev_abdullo@mail.ru.
CALCULATION OF MECHANICAL CHARACTERISTICS OF INDUCTION MOTOR USED IN TEXTILE MACHINERY AT THE ENTERPRISE RUSHAN TEKS IN BUKHARA CITY
Abstrtact: In given article the mechanical characteristic of an induction motor with a squirrel-cage rotor of the type 4A100L6Y3 with a power of 2.2 kW, 220/380 V voltage, a rotation speed of 950 rpm of the loom of the textile enterprise «RUSHAN TEKS» in the city of Bukhara is calculated.
Keywords: asynchronous motor, mechanical characteristics, starting torque, sliding, critical moment, rated torque, loom.
Looms are improving in our country more and more. The textile industry alone is complex and diverse. The cotton fabric manufacture is one of the main industrial sectors. Chemical fibre production, as well as cotton fibre, is developing in Uzbekistan. It allows us to extend the raw materials base of textile industry of the Republic of Uzbekistan and to expand the range of output products. Depending on the principles of fabric formation, the looms are divided into continuous and periodic looms. The continuous looms can be multi-wave and circular. The circular looms produce only baggy fabrics. Looms are not yet commonly used in the weaving industry due to the complexity of the machine structure and limited type of fabric produced. Depending on mechanism installed on the loom, there are: cam shedding, dobby and Jacquard looms. The cam shedding mechanism of the loom is the simplest, and is used in weaving cloths and fabrics with broken twill. Depending on the method of weft insertion, shuttle looms are divided into mechanical and automatic looms. The shuttle looms of AT type (fully automatic loom): AT-120, AT-175 (120, 175 - material width, cm). Depending on the method of weft insertion, weft looms are divided into mechanical and automatic looms. The shuttleless looms of CTB type
(shuttleless weaving loom): CTB 1-180, CTB 1-220, CTB 1-250, CTB 1-330; CTB 2-220, CTB 4-330. The number after the letters indicates the number of types of filling yarns. The air-jet looms are produced under the names P-105, P-125 etc. Looms with pneumatic rapier are tagged ATnP-120, ATnP-140. The speed of looms can be different depending on the method of picking, material width and the structure of some mechanisms. Weaving looms consist of mechanism and components and each of them has its own function. All mechanisms and components of the loom are driven by an electric motor. Mechanical power is transmitted from the electric motor by a special device (drive). Mechanisms transmitting motion from the motor to the operating device are called drives. Mechanisms used in looms depending on their design are divided into the following groups: lever, cam, gear, screw and wedge, friction, with a flexible link, hydraulic, pneumatic and electronic mechanisms. Each type of drive is characterized by the transmission speed and the number of gears. Each transmission mechanism has two main components: a drive and a driven link. In multiple-reduction drives, the spacer link is placed between the drive and the driven link. One of the most commonly used electric motors in looms are
Section 11. Technical science
induction motors. Three-phase squirrel-cage induction motors 4A100L6y3, 4A100S4y3, 4A112MA6y3, 4AHPM06y3, 4AHPM11B6y3 etc., have been installed in the looms of type CTE used at the RUSHAN TEKS Enterprise today. Their power is 2.2 kW-4 kW and volt-age-220/380 V. The electromagnetic torque may come from sources of two kinds, i.e: a) through electromag-
netic force and b) electromagnetic power. Below we will examine them in detail. The electromagnetic torque in an induction motor is created by the interaction between the rotating magnetic field produced by the alternating current in the stator windings (I2 cos f2), i.e. according to the Ampères force law an electromagnetic force is generated with magnetic flux, 0 F = Bli (Fig. 1).
O ' max em o v O /
Figure 1. Curves of distribution of electromagnetic forces (Fem) influencing magnetic induction of the air gap of the motor (Bs), the current in the rotor winding (i) and winding conductors of the induction motor
The electromagnetic torque created by this force is determined as follows:
M = C M '^max •12 ' COS^ (1)
where: CM = p ■ m2 ■ kch2 / >/2 is the constant; ^max - is the maximum value of the magnetic flux. The equation (1) is valid not only for induction motor, but also for all types of electric machines. This equation establishes a link between torque and physical events happening in the machine. Its use is very convenient in the qualitative process analysis in different modes. But the values (0 ,
J-J ^ max/
I2 and cos^2) included in this equation are not directly related to the supply-line voltage and machine operating conditions, and their experimental observation is very complex. For this reason the following equation has been derived, which allows to define the value of an electromagnetic (running) torque in the simplest way, to take into account influence of various parameters and operating modes of the machine. We express the electromagnetic (P ) and mechanical (P ) powers defined in the
v em' v mex/ *
power diagram through the electromagnetic torque:
Pem = M-«P Pmex = M > (2)
where:
co1 = (2 •%• n1/60) • (p / p) = = (2 •n/ p) • (p • n1 /60) = 2 •%• f / p;
and (o = 2 -n- n /60 is the angular velocity of the rotating magnetic field in stator and rotor respectively. According to the (2), the electromagnetic torque is equal to:
M = Pm /®1 (3)
Thus, the electromagnetic torque in the induction motor is proportional to its electromagnetic power. Using the power diagram, we can specify the following expressions to determine the losses in the rotor winding:
P e2 Pem Pmex (4)
or Pe 2 = M •ffl1 - M-w = M •(o1 -a). (5)
Multiplying the right side of the equation (5) by the ratio ((o1/rn1) we find the following: P'2 = M ■a1 ■ S. (6) From this equation (6) we have
M = P'e2/(œ1 ■ S) = m1 ■ (I'2)2 • r'2/(®! • S),
(7)
i.e. the electromagnetic torque in the induction motor is proportional to its power of electric losses in the rotor winding. Using a G-shaped replacement circuit, substituting the value of the rotor current I 2 to the (7) in view of (01 = (2-n- f )/p , we have the general electromagnetic torque equation of the induction motor:: M = (m • pU2 • r'2)/{2-n-f • S)•
•[(r + r' /S)2 + (x2 + x')2]}.
(8)
This (8) equation implies that for the induction motor with a power of P > 10 kW in the calculation of the
CALCULATION OF MECHANICAL CHARACTERISTICS OF INDUCTION MOTOR USED IN TEXTILE MACHINERY...
M moment, the complex number in the replacement diagram is assumed as c — 1. If it is necessary to calculate the electromagnetic torque more precisely, the expression (8) taking into account the complex number c1 is written as:
M = (m ■ pU2 ■ rT2)/{2-n-f ■ S)■ ■[(ri + c ■ rWS)2 + (x + c ■ x'j2]}, (85, a)
where Ci - 1,02 ^ 1,05 - is for the induction motors with a power of P ^ 10kW
In expressions (8) and (8, a), all values other than slip S are constant, and the slide varies directly as the mechanical load on the shaft. One of the main characteristics of the three-phase squirrel cage induction motor is the mechanical characteristic. Depending on the specific boundaries of this characteristic, we can define the operating conditions of the induction motor. Boundary of steady-state performances of this characteristic are usually determined by the Kloss formula:
M = 2■ MKp/(S/SKp + SKp /S), (9)
n; rpm 1200
where M - is the electromagnetic toque; MKp - is the critical moment; S - is the slip; SKp - is the critical slip. The mechanical characteristic of the induction motors can also be calculated using directory values and reference data. At the same time, the torques characteristic is definedby 4 points and the mechanical characteristic of the induction motor is calculated (Fig. 2). Point 1- is the no load operation of induction motor, where n = n0 = 60 ■ f / p, M = 0, where f - is the rotor frequency; p - is the number of pole pairs.
Point 2 - is the rated power setting of induction motor, where n = M = MH = 9550 ■ PH / nH, where Ph - is the rated motor output, kW;
Point 3 - is the critical moment, where n = nKP,
M = MkP MH ; Point 4 -is the starting torque, n = 0, M = MHT = ft- MH.
Figure 2 shows the calculation and construction of the mechanical characteristics used in looms with three-phase squirrel-cage induction motor of the type 4A100L6y3 with a power of 2.2 kW, 220/380 V voltage, a rotation speed of 950 rpm.
1000
10
20
30
40
50
60
Figure 2. The mechanical characteristic of the induction motor with a squirrel-cage rotor of the type 4А100L6У3
According to figure 2, it is defined that the nominal ing torque MHT=44 H • m , and the critical moment is torque of the induction motor is MH =22 H • m, the start- m =44 H • m M =48,4 H • m .
kP
kP
References:
1. SalimovJ. S., Pirmatov N. B. Elektr mashinalari.- T.: O'FMJN,- 2011.-408 b.
2. Berdiyev U. T., Pirmatov N. B. Elektromexanika.- T.: Shams ASA, - 2014.- 391 b.
