Three-phase asynchronous motor efficiency and power factor

 Induction motor efficiency and power factor is contradictory.For the same kind of Y series motor,high efficiency,low power factor.On the other hand,low efficiency,high power factor,high power,good for motor use;The power factor is low,will reduce the network transmission efficiency,because of low power factor,so the grid reactive power loss is big.So for ac induction attack efficiency indicators put forward higher requirements of wholesalemotor.blogspot.com both,puts forward higher requirements to the power factor index.The efficient and high voltage three-phase asynchronous motor,it overcomes the defect of old asynchronous motor,its insulation thickness thinning by the original unilateral 1.5 mm to 1.3 mm;Innovation design of star - Angle joint series hybrid hard winding method,reduce the stray loss of the motor,greatly improving the efficiency of the high voltage motor;Motor efficiency is low,the loss is big.For ac motor,is the resistance loss,in this way,the greater the loss of P in the power triangle,the greater the power factor Angle phi is smaller,the greater the power factor cos phi.Conversely,high efficiency,low loss,P is in the power triangle is smaller,the power factor Angle phi is smaller,the power factor cos phi is smaller.In order to satisfy the motor power factor,efficiency,two indicators,the backward of the structural design of centrifugal fan,a significant reduction in the high efficiency high pressure loss in the three-phase asynchronous motor machinery and noise.

The efficient high-voltage three-phase asynchronous motor can not only improve the work efficiency of the motor,and can also achieve the goal of reducing energy consumption,will be widely used in power stations,petrochemical,urban water supply,cement,paper making,metallurgy,coal and other industries,has an extremely extensive application prospect in the market,has significant economic and social benefits.Shell directly related to the personal safety and equipment protection grade selection of reliable operation,should be based on motor using occasions,to prevent human exposure to the motor internal dangerous parts,prevent solid foreign body into the chassis,prevent water from entering the shell cause harmful effects to the motor.Motor by letters IP protection grade plus two characteristics of Numbers,the first characteristic figures show that Motor vehicle the solid proof,the second feature figures show that the liquid.It is widely used in industry and People's Daily life.This kind of motor stator system group composed of group working system and starting winding.Its working principle are similar to those of three-phase asynchronous motor.The author through the analysis of the working principle of the single-phase capacitor motor to illustrate its positive &negative or transform a one-way operation of single-phase capacitor motor for positive and negative transfer lines of practical control circuit.

A.Simple working principle 1.When you don't answer the capacitance starting winding can a single phase or three phase asynchronous motor starting or running conditions,in terms of this item is set to the current in the winding of motor in whether can produce a rotating magnetic field.If not in the starting system group of the single-phase capacitor motor concatenated appropriate capacitor Tend to attend.If you want to improve the power factor,should reduce the motor air gap,increase the serial number of turns per phase.And rotor balancing machine to improve efficiency,increase should be ac motor air gap,which can reduce the harmonic stray loss,due to the harmonic stray loss and air gap of 1.5 ~ 1.6 power ratio.The two measures the reverse.When turn the timer can't start again,to the motor shaft by hand a little at this time can turn the rotation of the external force.After inspection found that the washing machine in the two capacitors,there is a short circuit phenomenon in a capacitor,the only change after short circuit capacitor in the same specification,then turn the timer when the normal operation of washing machines.In the washing machine motor is the typical positive &negative use capacitor motor control mode.Single-phase capacitor start motor is one of the single-phase asynchronous motor.

Electrical engineer for the selection of step motor

 

Stepper motor can transform electrical pulse signal into angular displacement or linear displacement.In the range of the rated power of the motor speed depends only on the pulse signal frequency and pulse number of control,and not affected by load change,coupled with step motor characteristics of cumulative error is small,in areas such as speed,position with stepper motor to control becomes simpler.Stepper motor three kinds,mainly is the hybrid stepping motor is widely used.When choosing a stepper motor,must pay attention to the following parameters as the manufacturer (are supplied with the motor):Step 1) from the Angle of: after receiving a step pulse motor rotation Angle.The actual interval Angle and fine fractions of the drive.Generally the precision of the stepper motor to step away from the Angle of 3-5%,not cumulative.2) number: the inside of the motor coil set number.Step phase number is different,is apart from the different Angle.If using subdivision driver,'phase number does not make sense: change the fine fraction can change electric motor cooling fan interval Angle.3) keep the torque: also called the largest static torque.

Refers to the rated power flow speed is zero,the external force force needed for the rotor rotational torque.Keep the torque has nothing to do with the drive voltage and drive power supply,etc.Stepper motor at low speed torque close to holding torque.As a result of the stepper motor output torque and power increases with the speed and constantly changing,so keep the torque is measured step motor is one of the most important parameters.Although holding torque is proportional to the electromagnetic excitation ampere turn,with the air gap between the rotor teeth.But too much by reducing the air gap,increasing the excitation ampere turns to improve static moment is not desirable,it will cause heating of the motor and the mechanical noise.Keep the torque type determined as follows: Stepper motor dynamic torque a while it is difficult to determine,tend to make sure the static torque of motor.Static moment of choice was based on motor work load,the load can be divided into two kinds of inertia load and friction load.Single inertial load,and there is no single friction load.Order more (generally by low speed) when (suddenly) starting when the two kinds of load are to consider,when accelerating (slopes) starting main consideration of inertia load,constant speed run into as long as considering the friction load.In general,keep the friction load torque should be within diesel generating set 2 to 3 times as well,holding torque once selected,motor frame and length can be set down.

permanent magnet synchronous motor mainly by permanent magnet synchronous motor rotor

The structure of the permanent magnet synchronous motor mainly by permanent magnet synchronous motor rotor,end cover,and composed of parts such as stator.In general,the biggest feature is its permanent magnet synchronous motor stator structure with the ordinary induction motor structure is very,very similar,is the main difference in the rotor's unique structure form the difference with other motor.The biggest different and common asynchronous motor is the unique structure of the rotor,the rotor with high quality on the permanent magnet poles.Placed on the rotor position of permanent acmotor2.blogspot.com magnets have many choices,so permanent magnet synchronous motor is usually divided into three categories: embedded,stickers and plug-in,as shown in figure 1.1.The performance of the permanent magnet synchronous motor is one of the most popular,there are many factors that can affect their performance,but the main is the structure of the permanent magnet synchronous motor.In terms of type,plug-in and embedded stick,all sorts of structure are all have their respective advantages. Stickers of the permanent magnet synchronous motor is the most widely used in the industry,its most main reason is electrical motor 12v 1000wthat it has a lot of other forms of motor incomparable advantages,such as its manufacture is convenient,the relatively small rotational inertia and simple structure etc.

And this type of permanent magnet synchronous motor is more easy to be the designer for the optimization of the design,one of the main methods are designed to approximate sine distribution of the air gap flux distribution structure,change the distribution structure to sine distribution can bring many advantages,for example,it brings negative effect,can reduce the harmonics of the magnetic field and the application of the above method can well improve the permanent magnet motors for sale running performance of the machine.Plug in the structure of the motor can compared with stickers of the motor is greatly improved because of its full use of it to design the structure of magnetic chain with asymmetry generated unique reluctance torque can greatly improve the power density of the motor,and can be easily produced,so the structure of permanent magnet synchronous motor is more used in the transmission system,but its shortcoming is also very prominent,such as production costs and compared with the stickers of the magnetic flux leakage coefficient is much larger.Embedded in the permanent magnet synchronous motor of permanent magnet is placed in the interior of the rotor,although in comparison to its structure is more complex,but there are a few obvious advantage is beyond doubt,because there are with high air gap flux density,the obvious compared it with stickers of the motor can produce a large torque;Because in the installation of the rotor permanent magnet is embedded in the choice,so by permanent magnet demagnetization after ac geared motor brought about by a series of dangerous possibility will be small,so the motor can run under higher rotate speed but does not need to consider whether the permanent magnets in the rotor will be destroyed because of the centrifugal force is too large.

To reflect the superior performance of the permanent magnet synchronous motor,compared with the traditional asynchronous motor to permanent magnet synchronous motor in particular,the most common type of rare earth permanent magnet synchronous motor with simple structure,high reliability;Very small volume,light quality special;Loss is relatively small,the efficiency is high;The shape and size of the motor can be obvious advantages such as flexible change.Precisely because it has so many advantages so that its application scope is very broad,almost throughout the aerospace,defense,industrial and agricultural production and daily life and so on each domain.Compared with permanent magnet synchronous motor and induction motor,consider not input reactive excitation current,so can be very obvious enhancement On its power factor,thus reducing the stator current and the stator resistance loss,and at the time of stable operation without the loss on the rotor resistance,which can reduce fan due to reduce the total loss of (small capacity motor can even without a fan) and the corresponding wind mill loss,compared with the same specifications of the induction motor with efficiency can be improved 2-8%.

Motor model parameters

Motor model is easy to use,design,manufacturing and other departments for business contact and

simplified technology files in the product name,specification,type of narration and referenced by a symbol.Product code is made up of motor type codes,codes of characteristics and design of the serial number of three section sequence.Motor type code with:Y-said asynchronous motor;T-synchronous

motor;Motor 220v electric motor characteristic code represent the performance of the motor,the structure or purpose and use of the Chinese phonetic alphabet. Such as explosion-proof type letters EXE (type) of increasing safety,EXB (flameproof),EXP (positive pressure type),etc.Design the serial number is high in center,core diameter,frame number,the flange 12v motor length,length of frame,core code,power,speed,or series of said.

Such as:Y2-160 M1-8 diesel generatorY:models,asynchronous motor;2:design the serial number,"2" for the first time based on the improved design of the product;160:high center,is the shaft center to the base plane height;M1:frame length specifications,M is medium,including footnotes "2" is the second M type core specification,type and "2" longer than "1" type iron core.8:pole,"8" refers to eight pole motor.Such as:Y 630-10/1180 Y said asynchronous motor;630 said power 630 kw;10,stator core diameter 1180 mm;The length of the frame adopt the internationally used symbol of letter;S is short frame type,M is the base type,type L is the length.Core length of letter with www.dongfeng-motor.com Numbers 1,2,3,in turn,said.

power factor compensation

An overview,In ac circuits,the phase difference between voltage and current cosine is called power

factor,with symbol cos said on numerical value,the power factor is the ratio of active power and

apparent power,namely the cosine = P/S.Power load of power grid,such as motor,transformer,fluorescent

lamp and the electric arc furnace and so on,mostly belong to the inductive load,the motor inductive equipment in operation process is not only need to absorb the active power in power system,also absorb reactive power at the same time.So the parallel capacitor reactive power compensation equipment installed in the power grid,will be able to provide compensation reactive power consumed by a perceptual load,reduce the power grid power supply side perceptual load and by line transmission of reactive power.Reduce the reactive power flow in the grid,can reduce the transmission and distribution lines transformer and bus power loss caused by the transmission of reactive power,this measure is called power factor compensation.Owing to the rise in the power factor is the root cause of the reactive power reduce,so often called power factor compensation of reactive power compensation.In a large system,reactive power compensation is also used to adjust the voltage of power grid,improve the stability of power grid.In a small system,through proper reactive power compensation method also can adjust the unbalanced three-phase current.According to the wangs theorem:in phase to phase and jumper inductor or capacitor can be transfer active current.For three-phase current unbalance of system,therefore,as long as appropriate in each phase to phase and phase zero access between different capacity of capacitors,acmotortrading.blogspot.com not only can be in each phase of power factor compensation to 1,and can make the active current of each phase equilibrium state.Second,the method System of compensation for reactive power compensation's main purpose is to improve the power factor.

Because of the power supply bureau of electricity is KVA or MVA to calculate,but the fee is to KW,which is actually doing useful work rate,a reactive power between the difference,in general is the reactive power in KVAR.Most lost work are inductive,that is generally called motor,transformer,fluorescent lamp.almost all of the lost work are inductive,capacitive is very rare.That is because of the existence of the inductive,caused a KVAR value in the system,is a trigonometric function relationship between the three KVA square = KW square+KVAR square Simple speaking,in the above formula,if today's KVAR value is zero,KVA will be equal to KW,the power supply bureau of 1 KVA electricity is equal to the user 1 KW consumption,the most cost-effective,so the power factor is a factor of power supply bureau is very care about.The power factor of the user if there is no ideal,relatively is the resource consumption in power supply bureau,so that is why the power factor is a regulatory restrictions.At present in terms of domestic power factor regulation must be between 0.9~1 inductive,below 0.9 need to accept the punishment.This is why we have to control the power factor in a very sophisticated.Some of the power electronic equipment such as rectifier,inverter,switching power supply,etc.; Saturable equipment such as transformers,motors,generators,etc.; Electric equipment and three phase induction motor price electric light source equipment such as electric arc furnace,fluorescent lamp,etc.,these devices are the main source of harmonic,the runtime will produce large amounts of harmonic.Harmonic on the engine,transformers,motors,capacitor etc all electrical equipment connected to the grid size,main show is harmonic generation additional loss,make the insulation of the equipment overload overheat and harmonic overvoltage accelerated aging,etc.Parallel to the line on the reactive power compensation capacitor to the harmonic amplification effect,causing the system voltage and current distortion is more serious.In addition,the harmonic current superimposed on the fundamental wave current of capacitor,can make the capacitor current of effective value increase,leading to higher temperature,reduce the service life of the capacitor.Harmonic current increase the copper loss of transformer,cause local overheating,vibration and noise increases,additional heating winding and so ac alternators 220v on.Harmonic pollution can increase cable transmission line loss.And harmonic pollution affect communication quality.When the current harmonic component is higher,may cause relay protection of overvoltage protection,overcurrent protection misoperation.Therefore,if the system is of high harmonic content,in addition to the series capacitor side need appropriate tuning (detuned) reactance,and installation of harmonic improve device for load characteristic project discussion.