Course Coordinator Prof. Suneet Tuli Presented by- Rupali Gupta (2012TTE2398) M.Tech 1 st Year Textile Engineering

What is a Motor? An electric motor is an electro mechanical device that converts electrical energy into mechanical energy. Mechanical energy is used to, for eg.- 1. Rotate pump impeller, fan, blower. 2. Drive Compressors 3. Lift materials Motors in industry: 70% of estimated load

How Does an Electric Motor Work? Reference:

Types of Motors Electric Motors Alternating Current (AC) Motors Direct Current (DC) Motors SynchronousInduction Three-PhaseSingle-Phase Self ExcitedSeparately Excited SeriesShuntCompound Reference: Energy Efficiency Guide for Industry in Asia –

DC Motors DC motors are used in special applications where high torque in the beginning or smooth acceleration over a broad speed range is required. These motors can be combined with number of options such as gear trains, clutches, breaks and filters. Image from

Important parts of a DC motor- Field Pole: North pole and south pole Receive electricity to form magnetic field. Armature: Cylinder between the poles. Linked to drive shaft to drive the load. Electromagnet when current goes through. Commutator: Overturns current direction in armature. Reference :

Limitations of DC Motors DC motors are available in a wide range of sizes, but their use is generally restricted- Low speed, low-to-medium power applications like machine tools and rolling mills because of problems with mechanical commutation at large sizes. They are restricted for use only in clean, non-hazardous areas because of the risk of sparking at the brushes. DC motors are also expensive relative to AC motors.

Induction Motors Most common motors in industry Advantages: Simple design Inexpensive High power to weight ratio Easy to maintain Direct connection to AC power source

Important parts of an Induction motor- Rotor Stator Reference: Energy Efficiency Guide for Industry in Asia –

Principle of Operation Electricity supplied to stator Magnetic field generated that moves around rotor Current induced in rotor Electromagnetics Stator Rotor Rotor produces second magnetic field that opposes stator magnetic field Rotor begins to rotate Reference: Energy Efficiency Guide for Industry in Asia –

Single-phase induction motor One stator winding Single-phase power supply Squirrel cage rotor Require device to start motor 3 to 4 HP applications

1.Run winding 2.Start winding 3.Start switch 4.Rotor 5.Start capacitor 6.AC supply

Three-phase induction motor Three-phase supply produces magnetic field Squirrel cage or wound rotor Self-starting High power capabilities 1/3 to hundreds HP applications: pumps, compressors, conveyor belts, grinders 70% of motors in industry!

Wound rotor type Motor This type of motors is used where high starting torque is required. (such as in carding machine starting load is very high so high starting torque is required)

Servo Motor  Servos operate on the principle of negative feedback, where the control input is compared to the actual position of the mechanical system as measured by some sort of transducer at the output. Any difference between the actual and wanted values (an "error signal") is amplified and used to drive the system in the direction necessary to reduce or eliminate the error.

 Servos are generally used in all type automatic textile machines such as ring frame, card, comber etc.  Servo drive of ring rail.

Variable Speed Motors  The primary function of a variable speed AC drive, is to convert electrical power to the usable form by variable frequency drive for controlling speed of AC motor.  Any variable speed electrical drive system comprises of the following components:  An electronic actuator - the controller.  A driving electrical machines motor.

Variable Frequency Drives Variable frequency drive controllers are solid state electronic power conversion devices with pulse width modulation. The usual design first converts AC input power to DC intermediate power using a rectifier or converter bridge. The rectifier is usually a three-phase, full-wave-diode bridge. The DC intermediate power is then converted to modulated sinusoidal AC power using an inverter switching circuit. The inverter circuit is probably the most important section of the VFD, changing DC energy into three channels of AC energy that can be used by an AC motor.

Mains three phase AC Rectifier Inverter switch with PWM technique Motor drive

Now a days when speed of operation varies with time, these drive give proper speed variation. For example in speed frame cone-drum are replaced by these drives. These drives have been launched for ring frame also.

Weft Accumulator  Generally optically sensor controlled SUMO motors are used to provide weft in rapier and air-jet looms.  These regulate tension in weft during weft insertion to reduce weft breakages.  It can be programmed to run at different speeds when desired.  These work on frequency modulation principal.

References (INDUCTION MOTOR) ECN Electrical Forum Discussion Forums for Electricians, Inspectors and Related Professionals EDUCYPEDIA – electronics (servo drives) The educational encyclopedia hyperphysics.phy-astr.gsu.edu/hbase/hframe.html Energy Efficiency Guide for Industry in Asia –