Motor common faults

 Common faults of three phase asynchronous motor are swept rotor chamber,vibration,winding turns or short circuit between the layers,winding grounding,stator winding lack of phase operation,the reverse of the stator winding unbalanced three phase current,core silicon steel sheet insulation damage,etc.Motor vibration generated when the noise and the additional load,may be bad driving device,can also be caused by the motor itself,such as the rotor dynamic balance is not good,shaft bending,installation does not reach the designated position,loose fasteners and so on.Motor open phase running the cause of the main line fuse is melt fuse or current setting values are not appropriate,touch switch contacts caused by the bad.If you run a long time,will burn out motor.Three-phase voltage imbalance or winding electric vehicle motor interturn short circuit will cause unbalanced three phase current,the stator winding end reverse connection will cause the motor temperature rise,winding grounding or short circuit can cause too much electricity,iron core silicon steel sheet insulation damage will cause motor overheating,etc.

In a word,in actual operation,to analyze the cause of the problem correctly,strengthen the patrol and maintenance,timely discover and eliminate the malfunction of the motor,as much as possible to ensure safe operation of motor Motor maintenance of motor start,first check the motor assembly is flexible,winding insulation resistance is in line with the requirements,the rotating part for jam,also check the motor start and protection equipment eligibility requirements,such as motor grounding device is in good condition,the selected low voltage circuit breaker,contactor,fuse configuration is correct,and so on.Motor start,start times cannot too much,otherwise the motor could overheat burn out.In the operation of the motor,to closely monitor the voltage,current and temperature,the motor operating electricalmotor1.blogspot.com voltage should be strictly controlled within the scope of the change,otherwise may cause motor overheating,also,the current is not too high or too low,because when the voltage must be,running current drag,it reflects the motor load,mechanical load,motor overload operation for a long time,the current will rise,make serious motor overheating,if the motor load is light,the formation of "big horse car",the motor capacity is not able to make full use of.In daily maintenance,also should closely monitor any abnormal noise or vibration motor,check whether the screw is fall off or loose,the motor repair and maintenance regularly,keep clear of the external dust,oil change on a regular basis.

The selection of the motor selection of motor,first of all to understand the mechanical load characteristics of the motor,according to the types and features of the mechanical load to select the rated capacity,rated speed and rated voltage of the motor and the pattern.For a production machine equipped with an electric motor,the first thing to reasonably choose the power of the motor.Usually according to the need of the production of mechanical load to select the power of the motor,at the same time,consider the work of load problem,that is to say,should be adapted to the selected motor mechanical load of the continuous nature of work,short-term or intermittent cycle.When the power to choose not too big,also not too small.Choose the small,can't guarantee the normal work of the motor and production machinery; Choose the big,motor fan although can guarantee the normal operation,but not the economy,motor capacity can not be make full use of,and motor often cannot full load operation,make the efficiency and power factor is not high.Secondly,according to the request of power supply voltage conditions,chooses Y series three-phase asynchronous motor rated voltage and frequency with the power supply voltage and frequency.The speed of the motor must be selected according to the requirement of the production machinery nameplate,otherwise may change in the production of mechanical performance.In addition,the structure,protection,cooling of the motor and installation form,should adapt to the requirement of using the environment conditions,and to strive for installation,debugging,maintenance is convenient,safe and reliable to ensure the motor can run.

The inverter from what respect to protection on the motor

Abstract:the frequency converter is widely used in various industries,mainly due to its energy saving and the function of the frequency control of motor speed in the working condition of equipment and system application,the frequency converter from what respect to the protection of motor? Tags:frequency control,frequency converter,motor,energy-saving frequency converter is widely applied in industry control engineering net all rights reserved,mainly due to its energy saving and the function of the frequency control of motor speed in the working condition of equipment and system application,so the inverter is from what respect to the protection of motor? Below we will analyze this problem solve.Frequency converter for motor protection mainly has the following several aspects:over voltage protection,low voltage protection,over current protection,open phase protection,reverse phase protection,overload protection,earthing protection,short circuit protection,overclocking protection and protection of the stall.Here are the several types of the frequency converter for motor protection method were introduced simply.1.The over voltage protection:the inverter output voltage detection function,frequency converter can automatically adjust the output voltage,the motor is not withstand overvoltage.

Even if the output voltage and output voltage adjustment by more rotor and stator than 110% of the normal voltage,electric motor cooling fan frequency converter can also through the outage protection for motor.2.The under voltage protection:when the voltage is less than 90% of the normal voltage of the motor,frequency converter to protect downtime.3.The over current protection:when the motor current by more than 150% of the rating / 3 seconds,or 200% of the rated current / 10 microseconds,frequency converter through the downtime to protect the motor.4.Open phase protection:monitoring the output voltage,when the output phase,frequency converter alarm,after a period of time frequency converter through the downtime to protect the motor.5.Reverse protection:frequency converter motor can only rotate along one direction,unable to set the direction of rotation,unless the user changes motor wiring A,B,C phase sequence,there is no reverse phase.6.Overload protection:monitoring frequency converter motor current,when the motor current is more than 120% of the rated current / 1 minute,the frequency converter via down to protect the motor.7.Grounding protection:frequency converter is equipped with special grounding protection circuit,generally made up of earthing protection of the transformer and relay,when a phase or two phase ground,inverter alarm.If the user requirements,of course,we can also design for the grounding protection immediately after downtime.

8.Short circuit protection:after the inverter output short circuit,inevitably cause over-current,within 10 microseconds inverter through down to protect the motor.9.Overclocking protection:frequency converter has a maximum and minimum frequency limit function,make the output frequency can only be within the prescribed scope,thus realizing the overclocking protection function.10.Stalling protection:general for synchronous motor stalling protection.For asynchronous motor CONTROL ENGINEERING China all rights reserved,accelerate the process of stall will be performance for current,frequency converter by over current and overload protection to realize the protection function.Reduction in the process of stall can be set in the process of debugging to avoid safety deceleration time.

Energy conservation to reduce running cost for a long time

Motor is an important industrial energy consumption equipment,widely used in areas such as fan,compressor,pump,mechanical transmission,its power consumption is more than about 60% of China's entire industrial power consumption,220v ac electric motor ssmall three-phase asynchronous motor power consumption accounts for about 35%,is a major drain,so the development of China's high efficiency motor is one of the important measures to improve energy efficiency,meet the needs of the development of our country,it is very necessary.Motor system energy saving project has been listed as China's 11th five-year plan is one of the ten major energy conservation projects,is the key areas of the country's energy conservation and emissions reduction work. magnet prices In the context of energy conservation and emissions reduction,mandatory standards and encourage policy determines the high efficiency and energy saving motor will fully replace the traditional inefficient,high efficiency and energy www.dongfeng-motor.com saving motor is a new motor design,new technology and new materials,by reducing the wastage of the electromagnetic energy,heat energy and mechanical energy,improve the efficiency of the output of the motor of the motor.

Compared with standard motor,motor with high efficiency and energy saving and energy saving effect is very obvious,under normal circumstances,the average energy consumption fell by around 10%,efficiency can be increased by about 4%. Expert analysis,in the whole life cycle of the motor,the purchasing price accounted for 2% of the total cost of the Motor vehicle motor maintenance costs accounted for 0.7% of its total cost,and the cost of energy consumption accounted for 97.3%. Therefore,considering from the whole life cycle of the motor,that is,from the design,manufacture of the motor to motor selection,operation,adjustment,repair,scrap,high efficiency and energy saving motor save energy consumption for the factory,reduce the life cycle cost and improve production efficiency and reduce environmental pollution,but also reduce energy consumption and reduce the emissions of carbon dioxide,conducive to the sustainable development of the factory. In short,the effect of energy saving for sustainable throughout the entire life cycle of mechanical equipment.

Star delta start

1 the principle Learn the electrician will not star triangle how line. 1. When the load on the motor has no strict requirements and to limit the start torque motor starting electric fan motor parts current and motor can use 380 v/Δ connection condition star triangle boot method; 2. The method is: in the motor when the motor first starts, connect into the star connection, when the motor start again after successful will convert into triangular connection (via double-throw switch switch); 3. Because of the motor starting current is proportional to the power supply voltage, the power grid provided by the starting current is only 1/3 of the full voltage start current, but also start torque only 1/3 of the full voltage start torque. 4. Star triangle start, step-down starting at the expense of his power in exchange for a lower cost of starting current. So it defies and with the size of the motor power to determine whether to need to use the star triangle start, also depends on what kind of load, the general load when need to start the runtime negative light load can be used star triangle start, usually a squirrel-cage motor starting current is 5 to 7 times that of the running current, and voltage requirements for power grid is usually plus or minus 10%, in order not to form the impact to power grid voltage is too large to adopt star triangle start, general requirements in squirrel-cage motor power by more than 10% of the rated power transformer will be will use the star triangle. 

5. In the process of actual use, found to be the star triangle step-down starting motor starting electricalmotor1.blogspot.com 11 kw are needed, such as fan, 11 kw electric current when it starts at about 7-9 times (100) A, according to the normal configuration of the thermal relay can't start, it's no use (the draft) thermal relay with big and does protect the motor, so suggest using step-down start. Two conditions 1, the capacity of 7.5 KW three-phase asynchronous motor. 2, motor in starting the instant power grid voltage fluctuation is less than 10%, for not often start the motor can be up to 15%; If there are special transformer S transformer or 5 p motor, motor asynchronous motor allows direct frequently. 3, meet the experience formula: Ist/IN < 0.75 + ST \ 4 pn ST - public transformer capacity, KVA; PN - motor rated power, KW; Ist / - IN the ratio of the motor starting current and the rated current. 4, star triangle step-down starting motor three-phase winding six external terminal: A - X, Y and C - B - Z (hereinafter with rated voltage 380 v motor as an example) A. start star: X - Y - Z, A, B, C three termination three-phase ac voltage 380 v, the voltage of each phase winding, 220, A 380 v directly start current is greatly reduced, to avoid the excessive starting current impact on grid form. At this time of the torque are relatively small, but the motor can reach a certain speed. B. angular run: star start the motor for a period of time (about) a few seconds after reaching a certain speed, electric switch connect six terminals into a triangle, and again from 380 v power supply when each phase winding voltage of 380 v, torque and rotational speed is greatly increased, the operation process of motor in the rated conditions.

The operation of the three-phase asynchronous motor monitoring

Three-phase asynchronous motor running monitoring: 1, monitoring, motor overheating 2, monitoring the working current of the motor is more than the rated current 3, monitor power supply voltage with or without changes 4, monitor whether the three-phase power supply voltage and current balance Note: in the operation of the three-phase asynchronous motor 1, pay attention to the ventilation of the motor and the environment 2, pay attention to the motor vibration 3, pay attention to the noise of the rotor cutting machine motor with or without abnormal situation 4, pay attention to whether motor abnormal smells 5, pay attention to the working condition and fever motor bearing Daily monitoring master electrician motor five often: 1, often listen to. Motor issue during normal working uniform "buzzing" sound. Particularly heavy motor part when I heard the "buzzing" sound, or "utter the word" sound, motor open phase running. If heard a continuous "guru" or "giggle" sound, that there is something wrong with the motor bearings 2, often have a look. See the ammeter or a voltmeter indicates whether or not the normal; See if three phase current balance; See whether the power supply voltage of three-phase; See if motor on the basis of solid, etc. 3, often monitoring environment temperature. The output power of the motor temperature has a great relationship with the surrounding environment, the environment temperature is higher, the smaller the motor output power. When the environment temperature below 35 ℃, motor power output will be greater than the rated power output, the increase of amplitude of (35) % (t for the actual environment temperature), but not more than 8% - 10%; When the environment temperature above 35 ℃, the output power of the motor than rated output power reduction (t - 35) %. 4, often feel. Back with your fingers touch the motor shell, temperature rise is too high. As the hot hand, motor has overheating. 5, often smell. Whether with his nose close to the motor, smell the smell of insulating varnish or anxious burnt flavour. If have, could be the result of a coil www.facebook.com/dongfeng.motor of motor overheating and short circuit, etc.