The choice of servo motor electrical engineer

 The choice of servo motor, the distinction between general electrical engineer in accordance with the generally divided into stepper motor, a dc servo motor, brushless dc servo motor, ac servo motor, with the increasingly progress of science and technology, many special servo motor arises at the historic moment, such as piezoelectric motor, linear motor, and the voice coil motor, here we mainly talk about general servo motor selection. Choose what kind of servo motor, to a large extent depends on the physical properties of the load, the load of job characteristics, system requirements and the working environment. Once the system requirement, no matter choose what kind of rotor cutting machine form of servo motor, the first thing to consider is right choose how much of a motor, main consideration physical characteristic of load, including the load torque, moment of inertia, etc. In the servo motor, usually measured in torque or force motor size, so choosing motor first to calculate the equivalent to the size of the shaft end load torque or force. After calculate the torque demand to set aside part of allowance, generally choose motor for times the load torque, torque to the ac synchronous motor reliable running of motor. 

In addition also needs computing reduced to the size of the shaft end load inertia, generally choose the load inertia: motor rotor inertia, to ensure the rapidity of the servo system response. If appear between the motor and load inertia, torque does not match the situation, so only at the expense of speed, increase speed reducer between the motor and load, then you need balance. After selected by how much torque motor, needs to do is to understand the working characteristic of load and working environment. Work load features include such as load is high or low speed running, the acceleration needs to how much, if demand is frequent start-stop, how frequency requirements, system running precision and so on. Then choose servo motor also has no specific rules to follow, the key is your choice of motor must adapt to work to beg you load movement. Such as the system accuracy is not high, the movement speed around hundreds of the following (not more than 500 RPM) but not too low (greater than 1), does not need to frequent start-stop, stepper motor is a kind of good choice. This is due to the stepper motor open-loop control, low control precision, acmotortrading.blogspot.com high speed, motor torque will drop quickly, will take the fixed load, low speed will be rotating discontinuous crawl phenomenon, and the response of the stepper motor is not fast, not suitable for frequent startup applications. When the speed a few turn to more than 3000 turn, relative to demand higher control precision, can choose straight flow or ac servo motor.

The motor itself the cause of overheating

A circuit,motor winding,when one phase winding break in the motor winding,or in the parallel branch has a branch circuit,will lead to unbalanced three phase current,overheat the motor.B,motor winding short circuit,when the motor winding short-circuit faults on the short circuit current is much bigger than the normal working current,make winding copper loss increases,cause the winding overheating,even destroyed.C,motor connection error,when misconnect into star delta connection motor,motor full load permanent magnet motors for sale operation,still more than rated current flows through the stator winding current,and www.dongfeng-motor.com even cause the motor to stop,if the shut down time is a bit long,not to cut off the power supply,winding is not only a serious overheating,will also be rotor and stator destroyed.

Misconnect when star connection of motor into a triangle,or several coil string into a branch set of motor fault into two branch in parallel,will overheat the winding and iron core,serious when will burn winding.E,motor ac electric motor parts connection error,when a coil,the coil group or a phase windings to reverse,will lead to serious unbalance of three phase current and make the winding overheating.F,the mechanical failure of the motor,when the motor shaft bending,there was something wrong with bad assembly,bearings,etc.,all can make the motor current increases,the copper loss and mechanical friction loss increase,make the motor over heat.

Motor pump concentricity adjust the special tool

In the oil pump room,three-phase asynchronous motor runs obvious vibration and noise is too big,bad pump shaft seal and drip,the phenomenon such as oil spills often occur.Analysis its reason,mainly by the motor shaft and pump shaft concentricity of installation and adjustment is not accurate,and the vibration in the operation of the motor and the bottom bolt looseness,caused by the motor shaft centerline offset.this Sample,motor and oil pump bearings will accelerate wear ac synchronous motor,even damage coupling or shaft of the motor and oil pump shaft.In modern industrial and agricultural production,national defense and transportation production areas of national economy,the application of the motor are widely,which can convert electrical energy into mechanical energy. But in actual production,the motor can damage caused by various reasons in the process of running or burned,and broken phase for protection circuit shall not be able to quickly cut off power supply when motor damage caused by the accident in production occupies a large proportion.According to relevant data,every year around the world need to be repaired by accident burned phase winding motor accounted for about 5% of the total installed motor sets about, And burned by phase motor in China accounts for over 70% of the amount of winding repair [1].Obviously,this will affect the production,have caused economic losses,visible,caused by the phase problem is quite serious,therefore necessary to asynchronous motor (especially the large and medium asynchronous motor) set up reliable phase failure protection device. 

To prevent Y series three-phase asynchronous motor open phase running,now,the existing traditional phase failure protection circuit consists of relay,contactor,completely because of circuit complexity,large volume,low reliability,failed to form a complete set of common use in practice [2].How to reduce the occurrence of these problems,improve the efficiency of the motor,is a question

worthy of consideration,the author According to many wholesalemotor.blogspot.com years of practice and the related data,analyze the cause and the damage of the end phase and zero sequence voltage as a starting point,puts forward the comprehensive open phase protection scheme.1 motor open phase 1.1 the cause of a phase power grid disconnection weather (such as the strong winds,heavy rain,blizzard,etc.),outdoor input power supply. Therefore,in the maintenance should be regularly

check and adjust the motor shaft and pump shaft concentricity. We have learned,at present in the oil depot mainly stainless steel ruler and hacksaw blade coupling,rotating shaft coupling,the clearance between the centrifugal pump coupling between the cylindrical surface and observe the ruler whether change,by using dial indicator turns the clock on both ends of the coupling oscillation situation,such as the clock oscillation is very small,say two axis of the concentric,adjust the end.But,when the coupling in mechanical processing,the concentricity (cylindrical center and inner hole,shaft end of the motor and pump shaft end) can't be very accurate,at the same time,the outside edge of normal could not very straight,with the naked eye observation with the coupling of the cylindrical gap is about values.In addition,when measured with a dial indicator,as a result of the movement of magnetic base,the datum has been changed,plus the processing error,but it's really hard to alignment motor pump Shaft concentricity.In view of the above,the use of special tools to accurately adjust motor pump shaft concentricity and can prolong the life of the motor pump,guarantee the smooth completion of the charge,hair oil task.

Asynchronous motor common faults of examination and ruled out

In the operation of the asynchronous motor in due to friction, vibration, insulation aging, hard to avoid failure.If these faults timely inspection, found and ruled out, can effectively prevent the happening of the accident.A, the asynchronous motor fault inspection 1.Listen to the voice, carefully to find fault point of ac asynchronous motor in operation, if found a finer "buzzing" sound, no change of high and low, is acmotor2.blogspot.com a normal voice, if the voice thick, and a sharp "buzzing", "hissing" sound is the forerunner of faulty, should consider the following reasons: (l) loose core motor vibration in the operation, the change of the high and low temperature, can make the iron core deformation of the retaining bolt, silicon steel sheet caused by loose, produce large electromagnetic noise.(2) the voice of the rotor spinning rotor noise, produced by the cooling fan, is a kind of "whoops" sound.Like drums of the "product" sound, this is the motor in sudden start, stop, reverse connect braking variable such as cases, the accelerating torque rotor iron core and the shaft with the loose, light person can continue to use, the person that weigh apart to check and repair.(3) in the operation of the motor bearing noise in, must pay attention to bearing the change of the voice, one end of the screwdriver to touch on the bearing cover, the other end on the ear, can hear the sound of the motor internal changes, different area, different fault, has a different voice.Such as crunching sound is produced by the irregular motion of the roll bearing inner gun, it related to the bearing clearance, grease state."Hissing" sound is metal, usually caused by bearing the lack of oil, add grease agent should open bearings.

2.The use of the sense of smell, failure analysis and motor is no peculiar smell in the normal operation, if the sensed the ignorance, is the fault signal, such as, anxious burnt flavour is insulation barbecue, and with the temperature increasing of motor, serious when Motor vehicle still can smoke; Such as oil coke, mostly lack of oil bearing, in dry grinding state near the end of the oil and gas evaporation of peculiar smell.3.Using the handle, check failure Touch the shell, can be broadly determine high and low temperature rise, if a touch the motor shell with the hand feel is very hot, the temperature is very high, should check the reason, such as: heavy load, the high voltage, and then for troubleshooting.Second, the common faults 1.The motor did not start torque, or won't start when there is no load and abnormal sound.Reason: (l) three-phase power circuit (including) the stator winding of knife switch, fuse one phase power, caused by single phase started.(2) the power supply voltage is too low.(3) bearing excessive wear, close to the one side of the stator and rotor caused by different heart of stator and rotor, air gap is not rotor balancing machine uniform.2.The motor starting torque is small, can't start, when the load, load increases when the motor stalling, sometimes send strong noise, local heating.Reason: low voltage grid and winding interturn short circuit, break or desoldering phenomenon in the rotor winding, start-up phase after a break caused by single phase operation.3.The starting current is big, and don't balance, noise big, cause protective device and cut off power supply.Reason: the stator winding wiring method may not be correct, winding of insulation aging.

2.2KW 3HP YC/YC2 capacitors series single phase ac electric motors

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