Check the reason for the unbalanced threephase power supply, if it is caused by the power voltage or the motor itself. Ambient temperature too high verify that the motor is getting enough air for proper cooling. They carry out precise stepbystep movements that are controlled by a drive. Dirty motors run hot when thick dirt insulates the frame and clogged passages reduce cooling air flow. 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. Franklin electrics web page, should be checked for the latest updates. Refer back to this diagram as the operational requirements of the singlephase motor are discussed. Test interphase resistance by disconnecting the leads from each terminal with a flathead screwdriver, then touch any two terminals with the two probes. 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. Threephase motors are normally used in commercialtype operations. If a single phase condition exists, correct the problem. If you find a phase on phase short, the motor needs evaluation for a rewind or for replacement.
Well learn how to identify windings, check windings resistance and insulation resistance. Therefore, motor troubleshooting involves the entire system, not just the. Simplified perphase equivalent circuit core loss is embedded with friction, windage and strayload loss v ag l d m ag d c l l p p p i r s s p i r s p i r p i r w z w z 3 1 3 3 3 2 2 2 2 2 2 2 2 2 1 2 1. The modern electric motor installation the individual motor drive has practically replaced all other types. Singlephase compressor models 6 threephase motors all dwm copeland threephase compressors can be started directonline dol. The singlephase induction motor is much the same in construction as the threephase motor.
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. How to test a 3 phase motor is discussed in this article. Diagnostics of rotor and stator problems in industrial. In the run winding of a split phase induction motor, how many poles are there.
If the motor doesnt rotate in twophase operation, find the reason for phase loss and eliminate it. Measure all 3 phases, add together, and divide by 3. Shadedpole motors are the simplest, employing a copper shading bar on one side of each main stator coil. Figure 173 shows a very basic oneline diagram of the singlephase motor. How to test three phase ac motors learning electrical. Check external cooling fan to be sure air is moving properly through the cooling channels. In a delta 3 wire 3 phase system, there is no neutral. It is true that single phase motors are less efficient substitute for 3 phase motors but 3 phase power is normally. The singlephase induction motor is much the same in construction as the threephase. By observing a few essential rules, you will ensure problemfree operation for many years.
Everything seems to be working just fine except for the 5hp motor that runs the horizontal spindle. However, troubleshooting a 3 phase power motor can actually help you fix the problem and get it working again. Three phase motors are normally used in commercialtype operations. Variety of 3 phase motor starter wiring diagram pdf. Troubleshooting threephase motors the extent of troubleshooting a 3o motor is dependent upon the motor s application. For the motor, test the stator winding resistance phase to phase and phase toground. Follow the steps below to check for the most common problems for threephase motors. This article describes ac electrical motor troubleshooting. Test inter phase resistance by disconnecting the leads from each terminal with a flathead screwdriver, then touch any two terminals with the two probes. Single phasing three phase only check the current at all phases. This is a brief course intended to acquaint you with basic electric motor troubleshooting and testing. Weg wiring diagram single phase motor and 3 start stop to motors. Rewinding us motors inverter duty motors space heaters trickle voltage heating reversing direction of rotation on tefc motors part winding start of a 12 lead y motor identifying leads of a 9 lead 3 phase motor adjusting end play oil foaming rewind data across the line connection of multilead motors bearing types lubrication instructions. Troubleshooting threephase motors the extent of troubleshooting a 3o motor is dependent upon the motors application.
All ecm motors slight cogging or rocking is inherent to all ecm motors motor is finding its location between stator and rotor and is determining rotation rumbling sound during startup and shutdown system mechanical resonance approx 300400rpm, three 3 permanent magnets stators cause the rotor to have a. Wiring diagram for 3 phase dol starter fresh 3 phase motor starter. It is true that single phase motors are less efficient substitute for 3phase motors but 3phase power is normally not available except in large commercial and. I would appreciate some guideance on how to troubleshoot a 25hp motor that is not running. Threephase motor and drive system and common problems.
Actually voltage or current unbalance will produce too much heat thus damaging the motors. If the motor doesnt rotate in two phase operation, find the reason for phase loss and eliminate it. If you have not been trained in how to work safely near live electrical circuits. Step by step troubleshooting of a 240v blower fan motor 3 speed, 1 phase. Conversion to mechanical power by motors pumps, fans, hvac, refrigeration compressors, power tools, food processors, escalators, elevators. Power supply test for three phase motors, the expected.
Here we are giving you only overview on 3 phases induction motor. Use features like bookmarks, note taking and highlighting while reading troubleshooting threephase electrical motors. Problems and premature failures often indicate input power system troubles, poor or deteriorating mechanical installations, or malfunctions in the driven machinery. Threephase dualvoltage motor insulation resistance testing threephase dualvoltage motors are used for most daytoday operations in todays industrial plants. Industries of today use three phase motors widely in highpower applications. These motors have fewer parts and are more sturdily built than their singlephase counterparts.
If you find a phaseonphase short, the motor needs evaluation for a rewind or for replacement. The following are the connection diagrams for standard 3phase general purpose 9lead and 12lead dual voltage motors. If you see very high resistance, say 500,000 ohms or more, the motor may be ok. Fri, feb 09 by troubles with the induction motors are generally divided into two categories. However, all threephase motors that run continuously in air conditioning or large freezer systems are susceptible to overheating if there is a voltage imbalance in one of the phases. Check the reason for the unbalanced three phase power supply, if it is caused by the power voltage or the motor itself. One is the electrical faults, such as the various faults of switches, buttons, fuses, electric brushes, stator winding, rotor, starting equipment and so. If the flow is weak or unsteady, internal air passages are probably clogged. These motors run conveyor belts, pumps, fans, and many other applications.
Inspect stator for defects, or loose or cut wires that may cause it to go to ground. Jul 17, 2017 in a delta 3 wire 3 phase system, there is no neutral. Unbalanced voltage three phase only check the voltage at all phases. This troubleshooting guide can also be applied to other types of three phase induction motors. Maintenance and troubleshooting three phase induction motor. For the motor, test the stator winding resistance phasetophase and phasetoground.
However, you might end up needing to rewind or replace it. Also the foundation of pump a foundation of motorpump must be rigid and secure to provide adequate support. For all other connections such as two speed motors, 1phase motors, alternate starting methods, etc. Most times, if a motor is failing it will be replaced immediately. Troubleshooting threephase electrical motors, brittian, l. Always keep hands and clothing away from moving parts. These motors have fewer parts and are more sturdily built than their single phase counterparts. The 3phase stepper motors are accurate, powerful and sturdy and excel with a high power density. If you find a phase toground short, a motor shop may be able to do an inplace repair for a large motor. Click on the image to enlarge, and then save it to your computer by right clicking on the image. Heat reduces insulation life and eventually causes motor failure. Troubleshooting threephase electrical motors kindle edition by brittian, l. Most domestic homes are powered by single phase power, but industrial facilities and electrical motors use 3 phase power more than any other component. Nov 23, 2015 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.
All ecm motors slight cogging or rocking is inherent to all ecm motors motor is finding its location between stator and rotor and is determining rotation rumbling sound during startup and shutdown system mechanical resonance approx 300400rpm, three. Im guessing that randy will need to get either a rotary phase converter or a vfd to generate the 3 phase his motor needs. W download it once and read it on your kindle device, pc, phones or tablets. For threephase motors, a threephase current sets up a rotating magnetic field that produces the starting torque without additional components such as switches. Three phase dualvoltage motor insulation resistance testing three phase dualvoltage motors are used for most daytoday operations in todays industrial plants.
How to troubleshoot a 3phase electric motor hunker. 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. If you find a phasetoground short, a motor shop may be able to do an inplace repair for a large motor. Aug 31, 2000 however, all threephase motors that run continuously in air conditioning or large freezer systems are susceptible to overheating if there is a voltage imbalance in one of the phases. Threephase dualvoltage motor insulation resistance testing. In this video you will find out how to test 3phase induction motor. An appropriate pump load all considerations of application, installation, and maintenance of submersible motors relating to these four areas are presented in this manual.
Motors are susceptible to the gradual failure of their insulation resistance. Diagnostics of rotor and stator problems in industrial induction motors by fang duan b. Oct 27, 2008 3 phase alternating current motor troubleshooting. How to test a threephase motor with a megger hunker. The positions of the bridges for directonline start depending on type of motor andor mains voltage are shown on the wiring diagrams. 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. All about motors page motor protection 83 notes on engineering 815 circuit documents 819 power supply 821 control circuit supply 824 contactor markings 825 directonline start of threephase motors 826 control circuit devices for directonline start 834 stardelta switching of threephase motors 835. If the voltage is present and correct, the motor is assumed to be the. An adequate flow of cooling water over the motor 4. Mar 28, 2018 in this video you will find out how to test 3 phase induction motor. As a result these motors are less prone to malfunctions and tend to operate for many years. If there is excessive dirt buildup, clean the motor. Troubleshooting three phase electrical motors kindle edition by brittian, l.
Use features like bookmarks, note taking and highlighting while reading troubleshooting three phase electrical motors. My friend called and said his pump motor was out and could i take a look at it. Working through the system motor to disconnect,overloads, contactor and fusses. All united states motor manufacturers produce motors to the requirement as standard. Because of their industrial use, if they are receiving the correct voltage, they are. This situation often develops when theres an uneven distribution of singlephase loads, either from a nearby panel or throughout the premises. 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. 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. 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.
In regard to single phase motors, a single phase current sets up a pulsating magnetic field, so single phase motors use several different methods to start figures 1 and 2. Take input voltage to the motor using the volt ohmmeter. Troubleshooting a 5hp, 3phase motor 1 speed, dual voltage since it has a total of four motors on it, i decided to get a transformer instead of trying to change all of the motor voltages over. Replace the motors protector with a new one of the same rating. A properly operating motor may be hot to the touch. Troubleshooting a 5hp, 3phase motor 1 speed, dual voltage. If you have not been trained in how to work safely near live electrical circuits, do not attempt to measure line voltages. This might result in unexpected motor failures when critical services from such motors are required affecting availability of plants. Hell get the benefit of variable speed and soft start with a vfd.
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