Check the reason for the unbalanced three phase power supply, if it is caused by the power voltage or the motor itself. Threephase motor troubleshooting free download as pdf file. Fault finding three phase induction motors motor will not start. Motor starters are types switches either electromechanical or solid state that are designed to start and stop the motors by providing the necessary power to the motor and preventing the.
Reduce the load or replace the motor with one of greater capacity. However, a 3phase induction motor may produce a starting torque and continue to run satisfactorily from a 1phase supply with the help of a static phase converter using a capacitiveinductive. Examine the motor s electrical connections and terminals. For this only the operating voltage, the motor rating, the various shortcircuit ratings and coordination types are required. This is a brief course intended to acquaint you with basic electric motor troubleshooting and testing. Is it due to coil damage inside of motor kindly reply, thank you. Some has suggested that electrical heat tracing is the solution. Oct 27, 2008 3 phase alternating current motor troubleshooting. Typical instruments used for troubleshooting motor operation problems include a multimeter, clampon meter,insulation resistance meter, and infrared thermometer. Most times, if a motor is failing it will be replaced immediately. Ueeneeg006a solve problems in single and three phase low voltage machines modification history notunit applicable descriptor unit descriptor 1 1. Essential for anyone who needs to buy, install, troubleshoot, maintain, or repair small to industrialsize electric motors, this practical guide contains new information on threephase motors along with coverage of the.
Dec 12, 2012 breakdown causes by electric motor failures always happen in our operation due to of 2 major factors. Testing a 3phase motor is as simple as holding the leads of a volt ohmmeter. Maintenance, inspection, repair, and trouble shooting, which is relevant. Fault identification of 3phase slip ring induction motor. The most popular type is the 3phase, squirrelcage ac induction motor. These instruments are used to measure voltage,current, resistance. Salient pole salient pole rotors the rotor is a large electromagnet with poles constructed of steel lamination projecting out of the rotors core. Maintenance and troubleshooting three phase induction motor. Single phase motors are found in a long and diverse list of devices like washing machines, mechanical clocks and generators. I had a similar situation on installing a new 10hp 3ph pump for a parts wash tank, the customer complained of nuisance tripping of the ol. I would appreciate some guideance on how to troubleshoot a 25hp motor that is not running. An induction motors rotor can be either wound type or squirrelcage type.
Compared to singlephase motors, its unusual for a threephase motor to be in a lockedrotor situation. Jul 17, 2017 a visual inspection of the motor and associated connections are important, if no obvious faults are seen you can test the 3 phase motor. The principle of operation of this motor is based on. Electric motor maintenance and troubleshooting, second edition explains in detail how all types of ac and dc motors work. The very first thing that you should do before starting any type of maintenance on a motor is a visual inspection, a lot of times the trouble can be found just by looking, because if the problem is that bad then it should be very obvious by observation. The basic steps in ascertaining the health of a threephase ac motor are given below. A three phase motor typically comes with a multiple of 2 poles for each phase. Learn how to diagnose voltage problems, size overload protection properly, and select the right motor for the job. Lecture 6 three phase induction motors cairo university. However, troubleshooting a 3 phase power motor can actually help you fix the problem and get it working again. The most popular type is the 3 phase, squirrelcage ac induction motor. How to test three phase ac motors learning electrical. From the data obtained from the noload test, we can determine the values for the series circuit elements r. Three phase alternating current or single phase design.
These instruments are used to measure voltage,current. However, a 3 phase induction motor may produce a starting torque and continue to run satisfactorily from a 1 phase supply with the help of a static phase converter using a capacitiveinductive. Motor specification is 415v, full load current 389a, and maximum current is 2800 a. The table below gives the commonly encountered problems in 3 phase squirrel cage induction motors, cause of problems and what remedy to apply to bring the motor back to production. Single phase motor troubleshooting pdf motor must be replaced or the stator rewound. A wound rotor, has a 3phase winding similar to the stator winding. Troubleshooting threephase motors the extent of troubleshooting a 3o motor is dependent upon the motors application. The three phase ac induction motor is a rotating electric machine that is designed to operate on a three phase supply. Repairing and reusing a 3 phase power motor is much more responsible than throwing away a motor that could be used with minor repairs. Motors are susceptible to the gradual failure of their insulation resistance. The heat over the induction motor is extremely hot.
It supplies an induction motor ich has a full load speed of 144wh 0 rpm. A three phase, 12 pole, salient pole alternator is coupled to a diesel engine running at 500 rpm. Everything checked out fine, so after a call to the manuf. The premise for motor operation is that if you can create a rotating magnetic field in the stator of the motor, it. The very first thing that you should do before starting any type of maintenance on a motor is a visual inspection, a lot of times the trouble can be found just by looking, because if the problem is that bad then it should be very obvious by ob. The best way to know for sure is check the voltage at the motor on all three legs. A three phase induction motor problem this application note describes how to set up, solve, and analyze the results of a twopole, three phase induction motor using rmxprt. The following are the connection diagrams for standard 3phase general purpose 9lead and 12lead dual voltage motors. If not, check supply circuitry, breakers and condition of the motor s power cord. Ueeneeg006a solve problems in single and three phase low voltage machines date this document was generated. If the motor is not in operation for a long period one week and above after installation or has been in operation but stopped for a period of time, the following precautions must be taken. A simple circuit diagram of contactor with three phase motor. The number of poles on the stator and rotor need to be the same.
Therefore, motor troubleshooting involves the entire system, not just the. An induction motor or asynchronous motor is an ac electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. Single phasing three phase only check the current at all phases. Threephase motor and drive system and common problems. There are two basic reasons for the use of single phase motors rather than 3 phase motors. Unbalanced voltage three phase only check the voltage at all phases. All about motors 88 motor protection selection aids the eaton selector slide enables you to determine quickly and reliably which motor starter is the most suitable for the application concerned. For this only the operating voltage, the motor rating, the various shortcircuit ratings and. Verify the motor phases have continuity from phase to phase for all combinations using a multimeter from the motor starter. This article describes ac electrical motor troubleshooting. Check red to blue, blue to yellow, and red to yellow phases.
Troubleshooting guide when motor overload trip electrical. Check the voltage in all three phases at the motor. Check external cooling fan to be sure air is moving properly through the cooling channels. It is mechanical component defect and electrical circuit failure. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. If you have not been trained in how to work safely near live electrical circuits. Bearing overheatingmotor amps in excess of nameplate full. For reason of economy, most houses, offices and also rural areas are supplied with single phase a. Follow the steps below to check for the most common problems for threephase motors. It is a maintenancefree, less noisy and efficient motor. If the motor doesnt rotate in two phase operation, find the reason for phase loss and eliminate it. Check the motor starter contactor, the fuses, and the overload. Mostafa elshahed objectives learn a brief history of the electrical power systems construction.
Three phase ac motor theory motors have been described as a transformer with a rotating secondary. Therefore, motor troubleshooting involves the entire system, not just the motor. For all other connections such as two speed motors, 1 phase motors, alternate starting methods, etc. List and describe the more commonly used equipment in an electric substation. My friend called and said his pump motor was out and could i take a look at it. Threephase motor troubleshooting electric motor fuse electrical. This 3 phase motor is also called as an asynchronous motor. It would not be unusual for a motor to single phase itself to death from a blown fuse, especially if the thermals were not correct. Examine the motors electrical connections and terminals. In starting up the motor, it will trip from 4 to 6 times. If there is excessive dirt buildup, clean the motor. For all other connections such as two speed motors, 1phase motors, alternate starting methods, etc. Singlephase motors are found in a long and diverse list of devices like washing machines, mechanical clocks and generators. Either an extreme voltage drop at the compressor terminals or a mechanical defect in the compressor will prevent the motor from restarting.
That way you can rule out the starter and all the conductors to the. Pdf operation of threephase induction motor with line to. Pdf operation of threephase induction motor with line. If not, check supply circuitry, breakers and condition of the motors power cord. Mar 28, 2006 fault finding three phase induction motors motor will not start. The motorspecified voltage must be present on all three phases. If the motor is used in an application that is critical to the operation or production, testing is usually limited to checking the voltage at the motor. Fault finding three phase induction motors circuit negma. The trick is knowing which leads to hold on to and which wires make no difference at all. Evening all, im confused seems to be happening a lot lately by the motor on my mill. The following are the connection diagrams for standard 3 phase general purpose 9lead and 12lead dual voltage motors.
Find the percentage slip and number of poles of the induction motor. Ummu salma ap objective a computer based protection system has been introduced to monitor the various faults of the induction motors and it is achieved with the help of the microcontroller. This troubleshooting guide can also be applied to other types of three phase induction motors. Now in the below diagrams, three phase motor will rotate in two directions viz forward and reverse. Breakdown causes by electric motor failures always happen in our operation due to of 2 major factors. Three phase squirrelcage induction motors are widely used as industrial drives because they are selfstarting, reliable and economical. Maintenance manual for three phase induction motors 5100 north ih35 round rock, tx. A threephase induction motor problem this application note describes how to set up, solve, and analyze the results of a twopole, threephase induction motor using rmxprt. Ueeneeg006a solve problems in single and three phase low.
If the voltage is present and correct, the motor is assumed to be the. It is preferable to find faults before complete motor failure. A 3 phase induction motor can be used for different applications with various speed and load requirements. Aug 31, 2000 all threephase units are highstartingtorque motors and are capable of restarting against a load.
After the load is disconnected, turn power on to try restarting the motor. Dear friends, 3 phase ind motor is overheated and also tripped during operation. Scribd is the worlds largest social reading and publishing site. This training teaches critical maintenance skills in an easy to use format. There are two basic reasons for the use of singlephase motors rather than 3phase motors. Two speeds one direction three phase motor connection power and control diagrams. A threephase induction motor problem enginuity systems. The stator is supplied by a balanced 3 phase ac power source.
Often the motor can run with incipient faults, but eventually it will lead to motor failure causing downtime and large losses. How to troubleshoot a 3phase electric motor hunker. Three phase dualvoltage motor insulation resistance testing three phase dualvoltage motors are used for most daytoday operations in todays industrial plants. The other way motor speed is measured is called actual speed. The model created by rmxprt will then be used as an input for empulse as a basis for performing more detailed analysis and for increasing the accuracy of the performance pre. Problems and premature failures often indicate input power system troubles, poor or deteriorating mechanical installations, or malfunctions in the driven machinery. They are recognizable as 3 bolt heads surrounding the bearing area.
An induction motor can therefore be made without electrical connections to the rotor. Fault identification of 3phase slip ring induction motor by, manivannan. Star delta starter for 3phase motor electronics hub. Threephase dualvoltage motor insulation resistance testing. Theres no centrifugal switch or capacitors to keep track of. An induction motor s rotor can be either wound type or squirrelcage type. The threephase ac induction motor is a rotating electric machine that is designed to operate on a threephase supply. Take input voltage to the motor using the volt ohmmeter. Differentiate between the various types of generating electric power stations.
With attention to concepts and practical skills, this training teaches a comprehensive approach to motor maintenance. The premise for motor operation is that if you can create a. Three phase motor connection reverse and forward power and control wiring diagrams. Ueeneeg006a solve problems in single and three phase low voltage machines.
Once you have tested a few 3phase motors, the process will come easily. Fault identification of 3 phase slip ring induction motor by, manivannan. If you have not been trained in how to work safely near live electrical circuits, do not attempt to measure line voltages. The nameplate of most ac motors lists the actual motor speed rather than the synchronous speed. The motor specified voltage must be present on all three phases. Motors, generators, and transformers are similar in that their basic principle of operation involves induction. Often the motor can run with incipient faults, but eventually it will lead to. These motors run conveyor belts, pumps, fans, and many other applications. Three phase motor connection schematic, power and control wiring installation diagrams. Overheating of three phase induction motor physics forums. The rotor terminals are connected to three slip rings which turn with the.
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