3 phase motor troubleshooting pdf

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. If not, check supply circuitry, breakers and condition of the motors power cord. The trick is knowing which leads to hold on to and which wires make no difference at all. 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. Note that this article is about troubleshooting threephase motors and drives. It shows the parts of the circuit as simplified shapes, and also the power and also signal links in between the tools. I also provide some simplified read rightish information about the electrical nature of the motor. Threephase dualvoltage motor insulation resistance testing threephase dualvoltage motors are used for most daytoday operations in todays industrial plants.

The best way to know for sure is check the voltage at the motor on all three legs. For the motor, test the stator winding resistance phasetophase and phasetoground. Therefore, motor troubleshooting involves the entire system, not just the. These motors have fewer parts and are more sturdily built than their singlephase counterparts. I would appreciate some guideance on how to troubleshoot a 25hp motor that is not running. That way you can rule out the starter and all the conductors to the. Once you have tested a few 3 phase motors, the process will come easily. How to troubleshoot 3 phase 240 or 480 volts any motor 3 leads 6 leads or 9 leads duration. How to troubleshoot motors and drives at the inputs fluke.

A typical 3 phase squirrelcage motor has six connection leads in the electrical connection box for the three coils. How to troubleshoot a 3phase electric motor hunker. It is comparatively easy to obtain the required speed through the use of motors directly connected to the driven machine, through speed reducers, or the now more economical geared motors, or even through vbelt or chain or sprocket drive. If the 3 phase compressor is a scroll compressor, be careful recording which wire is attached to which. If you have not been trained in how to work safely near live electrical circuits. Mar 28, 2018 in this video you will find out how to test 3 phase induction motor. The motor specified voltage must be present on all three phases. Telecommunication engineering, southwest jiaotong university, china, 2005 thesis submitted for the degree of masters of engineering science in school of electrical and electronic engineering the university of adelaide, australia august 2010. Testing and inspection of surge protection devices.

Vibration testing of motor after it has started running. Every good electrician knows the lead numbering sequence of three phase motors, or he has diagrams available for ready reference. If the motor does not start, turn it off and lock out the power. We would like to show you a description here but the site wont allow us. Check the reason for the unbalanced threephase power supply, if it is caused by the power voltage or the motor itself. How to test a 3phase motor gone outdoors your adventure. However, you might end up needing to rewind or replace it. Maintenance manual for three phase induction motors 5100 north ih35 round rock, tx. Second, the drive and its output, where the ac to dc converter, the dc filter, and the dc to ac inverter provide the three phase power to the motor. This article describes ac electrical motor troubleshooting. Measure all 3 phases, add together, and divide by 3. I am getting 230 volts 115 at each terminal marked with the red line in the image below. Use features like bookmarks, note taking and highlighting while reading troubleshooting three phase electrical motors. Threephase motor troubleshooting electric motor fuse.

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. Be sure the motor shaft key is captive before the motor is energized. Troubleshooting the problems 1, 2 as mentioned above, open the motor to find out the breakage and weld it. If a single phase condition exists, correct the problem. Even though a fault in your motor can be found out with the help of a multimeter, still becoming doubly sure really helps. Avoid long exposure in close proximity to machinery with high noise levels. Unlike a 3phase induction motor, a singlephase induction motor is not self starting but requires some starting means. Diagnostics of rotor and stator problems in industrial induction motors by fang duan b. How to test three phase ac motors learning electrical. My friend called and said his pump motor was out and could i take a look at it. A drive system consists of the 3phase stepper motor and the appropriate drive.

Reduce the load or replace the motor with one of greater capacity. Record all nameplate information for the induction motor. Threephase dualvoltage motor insulation resistance testing. If you find a phasetoground short, a motor shop may be able to do an inplace repair for a large motor.

The motorspecified voltage must be present on all three phases. With an ohmmeter, check the motor windings for any opens or shorts. After the load is disconnected, turn power on to try restarting the motor. Always keep hands and clothing away from moving parts. How to check the windings of a 3phase ac motor with an ohmmeter. Oct 27, 2008 3 phase alternating current motor troubleshooting. If someone works with ac 3phase motors, then it is important to know how to connect these motors in star and delta connection, and how to detect an electrical problem. Line start induction motor volts 220 amps 3 hp 1 phase 3 cycles 60 rpm 3600 serial 276247 frame 512 style c type ct temp 40 time cont i have 3 good legs from the wall. How to test a threephase motor with a megger hunker.

In troubleshooting a motor you may need to verify that the motor lead numbers are correct, and that there have been no electrical faults that create short circuits between the different phases. An electrical motor is an electromechanical device which converts electrical energy into mechanical energy. If the voltage is present and correct, the motor is assumed to be the. Checking windings in a 9 lead 3 phase motor duration. Mar 29, 2019 check that the windings are not open or blown. One singlephase wattmeter plus miscellaneous apparatus as needed.

Difference between single phase and three phase motor. On a 3 phase compressor, you will see the terminals listed as t1, t2, and t3. Testing a 3phase motor is as simple as holding the leads of a volt ohmmeter. If you see very high resistance, say 500,000 ohms or more, the motor may be ok. Aug 31, 2000 all threephase units are highstartingtorque motors and are capable of restarting against a load.

A wiring diagram generally gives info regarding the loved one setting. Well learn how to identify windings, check windings resistance and insulation resistance. In order to test a 3 phase motor further, you will have to conduct the following tests to find out if your motor is good or bad. If you find a phase on phase short, the motor needs evaluation for a rewind or for replacement. The 3phase stepper motors are accurate, powerful and sturdy and excel with a high power density.

If not, check supply circuitry, breakers and condition of the motor s power cord. This is a brief course intended to acquaint you with basic electric motor troubleshooting and testing. These types of motors are known as selfstarting induction motors. Troubleshooting threephase electrical motors, brittian, l. For the motor, test the stator winding resistance phase to phase and phase toground. If the motor doesnt rotate in twophase operation, find the reason for phase loss and eliminate it. Find the breakage with the multimeter and reconnect it. Indirect vector control washing machine threephase ac induction motor drive, rev.

Washing machine three phase ac induction motor drive, rev. Nov 27, 2019 an electrical motor is an electromechanical device which converts electrical energy into mechanical energy. The threephase motor currents are recons tructed from the dcbus cu rrent using an advanced reconstruction technique. Set the voltage setting of the insulation resistance tester to 500v. Most times, if a motor is failing it will be replaced immediately. Compared to singlephase motors, its unusual for a threephase motor to be in a lockedrotor situation. A wiring diagram is a streamlined conventional photographic representation of an electrical circuit. However, troubleshooting a 3 phase power motor can actually help you fix the problem and get it working again. The modern electric motor installation the individual motor drive has practically replaced all other types. If you have not been trained in how to work safely near live electrical circuits, do not attempt to measure line voltages. Roll motor leads be particularly concerned about reversing the motor. Resistance tests on resistance temperature detector rtd circuits. Three phase dualvoltage motor insulation resistance testing three phase dualvoltage motors are used for most daytoday operations in todays industrial plants. Does the issue follow the motor lead or stay in the same phase.

How to troubleshoot 3 phase motor with multimeter youtube. When the motor is coupled to equipment, ensure that system vibrations are within acceptable limit per iso 108161 to avoid failure of the motor. Maintenance manual for three phase induction motors tecowestinghouse motor company 5100 north ih35 round rock, tx. Follow the steps below to check for the most common problems for threephase motors. Threephase motors are normally used in commercialtype operations. Problems and premature failures often indicate input power system troubles, poor or deteriorating mechanical installations, or malfunctions in the driven machinery. Due to the high holding torque, a gearbox is not required in most cases. Examine the motor s electrical connections and terminals. Troubleshooting threephase motors the extent of troubleshooting a 3o motor is dependent upon the motors application. A threephase motor may run on a single power source, but it will not selfstart. 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. Take input voltage to the motor using the volt ohmmeter. Threephase motor troubleshooting electric motor fuse electrical.

A typical 3phase squirrelcage motor has six connection leads in the electrical connection box for the three coils. These motors run conveyor belts, pumps, fans, and many other applications. Here we are giving you only overview on 3 phases induction motor. Washing machine threephase ac induction motor drive.

I check the windings in the motor for my bradford lathe. Assortment of 3 phase motor starter wiring diagram pdf. Test inter phase resistance by disconnecting the leads from each terminal with a flathead screwdriver, then touch any two terminals with the two probes. Also the foundation of pump a foundation of motor pump must be rigid and secure to provide adequate support. Troubleshooting drop motor leads and verify output voltage phasetophase. If someone works with ac 3 phase motors, then it is important to know how to connect these motors in star and delta connection, and how to detect an electrical problem. Motors are susceptible to the gradual failure of their insulation resistance.

The 3 phase stepper motors are accurate, powerful and sturdy and excel with a high power density. This is different from a single phase compressor which will have 3 terminals listed as s, r, and c start, run and common. Single phase and three phase motors are two different types of ac motors. Scribd is the worlds largest social reading and publishing site. Either an extreme voltage drop at the compressor terminals or a mechanical defect in the compressor will prevent the motor from restarting.

Threephase motor troubleshooting free download as pdf file. Troubleshooting three phase electrical motors kindle edition by brittian, l. Test interphase resistance by disconnecting the leads from each terminal with a flathead screwdriver, then touch any two terminals with the two probes. If you find a phaseonphase short, the motor needs evaluation for a rewind or for replacement. Sample troubleshooting chart 3phase induction motor 20k pdf. Sine commutation allows for almost fully resonancefree operation of the motor. In that case, reach for a clamp meter like the fluke 337, and trace the cause because it could be one of. 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. The main difference between single phase and three phase motors is that a single phase motor runs on a single phase power source, whereas a threephase motor runs on a threephase power source. Many simple across the line single phase and 3 phase motors used in household appliances and industry respectively can be checked simply by changing the range of the ohm meter to the lowest offered r x 1, zeroing the meter again, and measuring the resistance between the leads of the motor. W download it once and read it on your kindle device, pc, phones or tablets. Maintenance and troubleshooting three phase induction motor. Diagnosing issues in a 3 phase air conditioning compressor. If you find a phase toground short, a motor shop may be able to do an inplace repair for a large motor.

How to check the windings of a 3phase ac motor with an. Repairing and reusing a 3 phase power motor is much more responsible than throwing away a motor that could be used with minor repairs. For a three phase motor, insulation resistance is usually measured between each motor winding or phase and between each motor phase and motor frame earth using an insulation tester or megger. One single phase wattmeter plus miscellaneous apparatus as needed. Many simple across the line singlephase and 3phase motors used in household appliances and industry respectively can be checked simply by changing the range of the ohm meter to the lowest offered r x 1, zeroing the meter again, and measuring the resistance between the leads of the motor. Once you have tested a few 3phase motors, the process will come easily. Help troubleshooting single phase motor electrical. Diagnostics of rotor and stator problems in industrial. Examine the motors electrical connections and terminals. This troubleshooting guide can also be applied to other types of three phase induction motors. You should also make a dc measurement of stator winding linetoline resistance. The rotor will constantly be turning to align its magnetic field with that of the stator field.

Unlike a 3 phase induction motor, a single phase induction motor is not self starting but requires some starting means. Sometimes, the temperature youre sensing may result from current unbalance. Checking windings in a 9 lead 3 phase motor youtube. Many not all single phase and 3 phase electric motors such as those used in equipment and appliances found in homes can be tested across the leads for an open winding in the motor. The 3phase set of currents, each of equal magnitude and with a phase. Therefore, motor troubleshooting involves the entire system, not just the motor. Threephase motor and drive system and common problems. Before troubleshooting the 3 phase induction motor, we must have to know about the 3 phase induction motor, star delta starter and its connection diagram. Testing a 3 phase motor is as simple as holding the leads of a volt ohmmeter. A drive system consists of the 3 phase stepper motor and the appropriate drive. Many not all single phase and 3phase electric motors such as those used in equipment and appliances found in homes can be tested across the leads for an open winding in the motor.

Power supply test for three phase motors, the expected. The basic idea of an electric motor is to generate two magnetic fields. The motor is not drawing any amperage at all and is making no noise at all. As a result these motors are less prone to malfunctions and tend to operate for many years.