Factors Affecting of an Ac Induction Motor Design

Factors Affecting the Design of an

Ac Electric Induction Motor1

Author: Baljeet

Factors affecting the Design of an ac electric induction motor

Design of an ac electric motor is directly affected by the length of the air gap. Ampere Conductors value also affects the design of an ac electric motor.

The value of average flux density over the air gap of an ac electric motor also affects the design of an ac electric motor. The size or dimensions of an ac electric motor depend upon the speed of an ac electric motor. It can also be said that the volume of active parts of an ac electric motor varies inversely as the speed of an ac electric motor. The value of output co-efficient is directly responsible for the dimensions of an ac electric motor. In other words the volume of active parts of an ac electric motor is inversely proportional to the value of output co-efficient of the ac electric motor.

The total flux around the armature (or stator of an ac electric motor) periphery at the air gap is called the total magnetic loading. While total electric loading is the total number of ampere conductors around the armature (or stator of an ac electric motor) periphery. Since the output coefficient of an ac electric motor is proportional to the product of specific magnetic and specific electric loading of an ac electric motor, we conclude that the size and hence the cost of ac electric motor decreases if increased values of specific magnetic and electric loading are used. The flux density in iron parts of an ac electric motor is directly proportional to the average flux density in the air gap of the ac electric motor. In a well designed ac electric motor the maximum density occurs in the teeth of the ac electric motor and therefore let us relate the flux density in the teeth with flux density in the air gap of ac electric motor.

The magnetizing current of an ac electric motor is directly proportional to the mmf required to force the flux through the air gap and the parts of the ac electric motor. The mmf required for the air gap of an ac electric motor is directly proportional to the gap flux density i.e. the specific magnetic loading of an ac electric motor. The consideration of magnetizing current is very important in ac electric induction motor(s) as an increased value of magnetizing current means of a low operating power factor of ac electric motor. Therefore specific magnetic loading in the case of ac electric induction motor(s) is lower than that in dc electric motor(s).

The core loss in any part of the magnetic circuit of an ac electric motor is directly proportional to the flux density for which the ac electric motor is going to be designed. Thus a large value of specific magnetic loading in an ac electric motor indicates an increased core loss in ac electric motor and consequently a decreased efficiency of ac electric motor and an increased temperature rise of ac electric motor. In case of high frequency ac electric motor, specific magnetic loading must be reduced in order to get lower iron losses in ac electric motor so that reasonable values of efficiency may be maintained in an ac electric motor. The maxmium temperature rise of an ac electric motor is determined by the type of insulation material used in the ac electric motor. If the cooling co-efficient of the ac electric motor is small, a high value of specific loading may be used in the ac electric motor.

About the Author:

Softbit provides CAD/CAM software packages for Electrical Machine Design, Industrial Automation products such as Remote Data Logger. Company aims to satisfy the current and future needs of its valued clients. We strive for customer’s satisfaction; our aim is technology dedication & continual improvements. http://www.softbitonline.com/ ac electric motor

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Factors affecting the speed-torque characteristics of an Induction motor :

The speed-torque characteristics are affected by various factors like applied voltage, R2’ and frequency.

(a) Applied voltage : We know that T µ V2. Thus not only the stationary torque but also the torque under running conditions changes with change in supply voltage.

(b) Supply frequency : The major effect of change in supply frequency is on motor speed. The starting torque is reduced with increase in frequency.

(c) Rotor resistance : The maximum torque produced does not depend on R2’. However, with increase in R2’, the starting torque increases. The slip at which Tmax is reached increases too which means that Tmax is obtained at lower motor speeds
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What is an Energy-Efficient Motor?

Motor efficiency is the ratio of mechanical power output to the electrical power input, usually expressed as a percentage. Energy-efficient motors use less energy. Because they are manufactured with higher quality materials and techniques, they usually have higher service factors and bearing lives, less waste heat output, and less vibration, all of which increase reliability. This is often reflected by longer manufacturer’s warranties.
To be considered energy-efficient, a motor’s performance must equal or exceed the nominal full-load efficiency values provided by the National Electrical Manufacturer’s Association (NEMA) in their publication MG-1. The Energy Policy Act of 1992 (EPACT) required most general purpose motors between 1 and 200 horsepower for sale in the U.S. to meet these NEMA standards by October 24, 1997.

What Efficiency Value Should I Use?
When comparing two motors, be sure to use a consistent measure of efficiency. "Nominal" efficiency is best. This value is obtained through standardized testing. "Minimum" or "guaranteed" efficiency is slightly lower to take into account typical variations in efficiency within a population of motors.

When Should I Consider an Energy-Efficient Motor?
Assuming 6 cents per kWh electricity cost and a payback criteria of 2 years, most motors should be replaced with an energy-efficient model if they operate over 4,000 hours per year. In general, energy-efficient motors should be considered in the following circumstances:
New installations, both separate and as part of packages such as HVAC systems
When major modifications are made to a facility or a process
Instead of rewinding older, standard-efficiency motors
As part of a preventive maintenance or energy conservation plan
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AC Induction Motor Design Software

Electric Motor Design Software
AC Induction

FEATURES
- Microsoft ® Windows™ based program
- Analysis tool used in design of Poly Phase and Single Phase Motors,
including Capacitor Start, PSC and Split Phase
- Computes all relevant motor parameters
- Allows printing of inputs, outputs & graphs
- Multi-window tasking
- Important constants built into program
- Variable definitions instantly available on screen
- Reduces development cycle time and cost
- Instantly check effects of design change
- Maximizes material usage
- On-line design tips
- Reduce number of prototype iterations

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Ac Electric Motor Design – Software1

Author: Baljeet

AC Electric Motor Design - Software


Softbit presents an easy way to design LT, 3 ph, TEFC, squirrel cage ac electric motors with the help of "AC Electric Motor Design Software". You just need to enter a few preliminary inputs and click a button. What you get is an output "Design Sheet" containing more than 100 output parameters required to build an ac squirrel cage electric motor. You can start to design from a small fractional horse power ac electric motor to a 200 hp ac electric motor using this design software. Higher hp modules are also available on request. You have the options to change any of the values from output design data to match your specifications and need. With the change in any of these values, the remaining parameters change automatically, without affecting the output design and performance of the motor.

What you can Change

You can change any parameter from the design data sheet like no. of slots, type of cage, material of cage conductor (Al or Cu), length of stator, bore of stator, core type / material, rotor dimensions, stator length, shaft diameter, shaft length, supply voltage etc.,. to get a better and most suited design for your requirement. Accordingly motor winding data will also change.

Why to change the output parameter

What ever results you get through this design software are as per calculations done using the formulae used to design a squirrel cage ac electric induction motor. Now suppose you get a rotor diameter as X and rotor length as Y but the job and place do not permit you to use these dimensions of rotor or say motor then you just change the value of either X or Y to best suit your requirement and all the related output parameters will change automatically. So you can customize the design as per yours, your client's or job's requirement.

Values you need to enter at the start

When you start designing a squirrel cage ac electric motor, certain preliminary values are required to be fed to the software to give the out put parameters. So you need to enter - capacity of motor in hp / kw, poles, supply voltage, rpm, frequency and certain more that the software will ask you at the time of start.

About The Software

The software has been developed keeping in mind to give our design engineers and professionals more flexibility while they are designing a squirrel cage ac electric motor. This window based software is very much user friendly. It gives you numerical, pictorial and graphical out puts to easily understand various design data values. It is flexible enough so that you can change any output design data value as per your requirement and get the changed values instantly, without affecting the final design and performance of motor. Its worth buying as it saves time, energy, gives more accurate results in shortest time, data comparison easy.

Factors affecting the Design of an ac electric induction motor

"An electric motor converts electrical energy into rotating mechanical energy or an electric motor is a machine that converts electrical energy into rotating mechanical energy. AC electric motor works on the principle of electro - magnetic induction".

Who Should Buy?

Every professional linked with motor design, QC, production, purchase, maintenance, repairer & re-builders, training professionals, engineering students, end users of electric motors must posses this motor design software.

Price v/s Benefits

This software is developed for the engineers with an aim to get high productivity and easy to learn features, with full documentation that includes extensive information on machine theory and design. Motor design with this simulation is interactive and fast. However, this software does not do the engineer's job. It is simply a specialized calculating tool to assist the design engineers with initial sizing and preliminary design of a motor by providing a simple intuitive interface and quick simulation.

About the Author:

Softbit provides CAD/CAM software packages for Electrical Machine Design, Industrial Automation products such as Remote Data Logger. Company aims to satisfy the current and future needs of its valued clients. We strive for customer’s satisfaction; our aim is technology dedication & continual improvements. http://www.softbitonline.com/ Power transformer design

Article Source: http://www.articlesbase.com/business-articles/ac-electric-motor-design-software1-222240.html

AC Motor Calculation

AC Motor Calculation

Calculate the Full Load Current of AC Motor

INDUCTION MOTORS ANALYSIS

Equivalent circuits of three-phase induction motor

Estimation of Induction Motor Parameters

Estimation of Induction Motor Parameters Program

Power and Efficiency

Power flow in an Induction motor

Losses and Efficiency of Induction Motor

Program

Calculation Equivalent of induction motors program

The Difference Between AC and DC Electric Motors

The Difference Between AC and DC Electric Motors
By John Francis

There are two main types of electric motors. There are direct current or DC and alternating current or AC motors. The reference of DC or AC refers to how the electrical current is transferred through and from the motor. Both types of motors have different functions and uses. Dc motors come in two general types. They can have brushes or be brushless. AC motors, as well, come in two different types. They can be two phase or three phase. The differences in DC and AC motors are sometimes subtle, but these differences are what make one types better for a certain use.

Direct current or DC electric motors work for situations where speed needs to be controlled. DC motors have a stable and continuous current. DC motors were the first and earliest motors used. They were found, however, to not be as good at producing power over long lengths. Electric companies found using DC motors to generate electric did not work because the power was lost as the electric was transmitted. Brush DC motors use rings that conduct the current and form the magnetic drive that powers the rotor. Brushless DC motors use a switch to produce the magnetic drive that powers the rotor. Direct current motors are often found in appliances around the home.

Alternating current or AC electric motors are used differently based on what type of AC motor it is. Single phase AC motors are known as general purpose motors. They work well in many different situations. These AC motors work great for systems that are hard to start because they need a lot of power up front. Three phase, also called polyphase, AC motors are usually found in industrial settings. These motors also have high starting power built transmit lower levels of overall power. AC power gets its name from the fact that it alternates in power. The amount of power given off by an AC motor is determined by the amount of power needed to operate the system.

DC and AC electric motors are found everywhere from the home to the car to industrial plants. Motors are important to everyday life. Dc motors were introduced and caused a great revolution in the way many things are done. When AC motors came on the market the way motors were looked at changed because of their amazing starting power potential. DC motors and AC motors are different in many ways, but they still both are usede to power the world. http://electricmotors-hq.com Everything you need to know about electric motors from their history to buying new and used.
Article Source: http://EzineArticles.com/?The-Difference-Between-AC-and-DC-Electric-Motors&id=193767

Differences in AC Motor Controls

Differences in AC Motor Controls
By Mike Imprixis

Every AC motor needs to be accompanied with an efficient motor controller to ensure proper functioning. Installing such a control system can prove to be beneficial as it can serve you in a number of ways. It may include a single device or a group of devices that manage the entire working of the motors in a preset manner.

These efficient motor controllers have different functionalities for different motor types. AC induction motors primarily induce current into the rotor windings without being physically connected to the stator windings. The induction motor drives uniquely feature electrical isolation and self-protection against faults. They usually comprise a device programmer, in-circuit debugger, motor control development board, a high voltage motor and a 3-phase or 1-phase high voltage power module. Usually, most of the industrial applications call for three-phase windings. This is because these motors allow variable speed control and considerable power in any kind of setting.

Sophisticated AC motor controllers are commonly referred to as motor drives. They balance the signal type with the control signals. The signal type is either analog or digital like power and voltage signals. The controllers can also work for power conversion, increasing the signal waves and sequencing the waveforms. You can fit in these motor drives in diverse types of AC motors.

The synchronous motors are those, which operate at a constant level of speed up to the full load. They do not slip in order to produce torque. These motors are driven by inverter controllers and feature a huge list of functions such as electro-mechanical braking, electronic power assisted steering, motor torque regulation, and many more. You can choose them for several industrial and automotive applications, so as to ensure the highest productivity for your machines.

Among the extensive collection of AC motor controls, the vector drive motors can control both the voltage and the frequency in an independent way. This eventually results in low-torque turnouts. The pole changing motor controls, suited to the synchronous AC motors, takes care of the pole number. This is a way to alter the number of poles in the primary winding.

Another variety of synchronous motor control includes the AC servo motor controls that make use of brushless commutation with necessary feedback. The most prevailing technologies utilize the concepts of moving coil, switched reluctance designs and moving magnets. You need to study your requirements well in order to purchase the most suitable controls for your motors. Some of the designs use encoders and resolvers to get adequate feedback regarding speed and position.

Inverter drives constitute a very common type of motor control system. They convert inputs in AC power to outputs with DC power. Again, if you require motor controls with very high frequency, then you can choose from a wide array of high frequency drives. These drives are used to supply power to the AC motors at substantially high frequency, as compared to the common power applications. You can also opt for the variable speed drives that serve you by adjusting and controlling the speeds of your motors.

An AC motor performs optimally through the controlled usage of electric power and sufficient savings on the expenditure of the owners. These motors were invented for the purpose of applying the system of alternate current transmission, in order to give an overall voltage control. If you own a medium or big cap factory, installing these motors can be quite cost saving. They provide efficient generation and distribution of electric power over long distances.

Article Source: http://EzineArticles.com/?Differences-in-AC-Motor-Controls&id=1872530

Calculate the Full Load Current of AC Motor

Figure 2 is the menu of the data which defines the electrical and
the thermal model of the motor.

Figure 2: Menu of Essential Motor Data

To fill in the data, we have used the stated voltage and horse
power to calculate the full load current:

We used 6 times full load current as the locked rotor current and

calculated the full load speed using one percent slip at full load.

Depending on the class and application of the motor, the locked

rotor torque can take on values of 0.8, 1.0, or 1.2. The value of

0.8 is the appropriate value for a pump motor.

Source pdf
http://www.selinc.com/techpprs/6023.pdf

Calculation Equivalent of induction motors program

Calculation the equivalent circuit of AC induction motors program

REMCAD

The program is designed for users and designers of electric-motor
drives with AC induction motors powered by Frequency inverters.

DESCRIPTION OF THE PROGRAMThe RemCad program can be

used for:1.1 the storage of basic machine data1.2 the calculation

and drawing of the characteristics on the basis
of the Equivalent Circuit (Torque, PowerFactor, Efficiency,
InputPower etc.)1.3 The export of the calculated data
The calculation and drawing of the characteristics on the basis of
the equivalent circuitThe following characteristics are drawn and

calculated:- the Moment characteristic dependant on frequency

and current
(current being the parameter)- the PowerFactor characteristic

dependant on frequency and current (current being the parameter)-

the Efficiency characteristic dependant on frequency and current
(current being the parameter)- the InputPower characteristic

dependant on frequency and current (current being the parameter)

The calculation is performed on the basis of the equivalent circuit
of the asynchronous machine.

Fig 1. Equivalent Circuit Diagram of AC induction machine

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