Dec 30, 2018 voltage is measured at the motor terminals and at the time of test, it should be approximately balanced. If the motor shaft still does not turn, the bearings are not turn frozen. Introduction to threephase motor types electric equipment. Motor shaft does disconnect the motor from the load. How to check winding resistance on a 230460v, 3phase, 60hz, 9. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. If any particular phase fails the continuity test, your motor is probably burnt. Usually an industrial induction motor is a threephase unit whose output shaft drives a load such as fan, conveyer belt, augur, saw blade or crusher.
Knowledge of the basics together with powerful new test equipment vastly simplifies the job. The threephase systems online electrical course covers threephase motor principles for induction, synchronous, and multispeed dualvoltage motors. Testing a 3 phase motor is as simple as holding the leads of a volt ohmmeter. Stator frame it is the outer most part of the three phase induction motor. As this is a grundfos publication, it is only natural that we should pay special attention to motors used for pumps although much of the information contained within these pages. The windings all three in a threephase motor should read low but not zero ohms. Check all three wires singly t1,t2,t3 all three phases to the ground wire. Table 4 references the motor horsepower rating, single phase and three phase, total effective kva required, and the smallest transformer required for open or closed transformer capacity single phase or three phase note. When an electric motor fails to start, runs intermittently, runs hot.
Draw the approximate equivalent circuit for the motor. Motor overheats motor is single basic electrical tester,check each of the three phase power lines for correct voltage. Once you have tested a few 3phase motors, the process will come easily. Guide for the use of electric motor testing methods based on iec 6003421 p ll determined from residual loss 8. How to check winding resistance on a 230460v, 3phase, 60hz, 9 lead motor nord drivesystems group. Motors are susceptible to the gradual failure of their insulation resistance. A wye system allows the use of two different voltages from all three phases, such as a 230400 v. How to test a 3phase motor with a multimeter sciencing. Maximum efficiency is usually near 75% of rated load. Mar 29, 2019 check that the windings are not open or blown.
Covers principles of three phase motor starters, part winding, reversing, jogging, alternator principles and operation. For bearings fitted with proximity probes, the unfiltered peaktopeak value of vibration including. The 3phase set of currents, each of equal magnitude and with a phase. Electric motor testing is usuallly the first thing to be sacrificed when cutting back on operational expenses. The electricity is fed into the interior of the motor, where it creates a magnetic field that pushes the strator and makes it rotate, turning the motor shaft.
The three phase systems online electrical course covers three phase motor principles for induction, synchronous, and multispeed dualvoltage motors. It is a type of polyphase system and is the most common method used by electrical grids worldwide to transfer power. Ieee std 1122004, ieee standard test procedure for polyphase. Y2 series three phase asynchronous motor is a kind of totally enclosed fancooled tefc squirrelcage induction motor.
Three ways to run a three phase motor on single phase, and. Each phase to phase must have a continuity if winding is ok. The theory used in the work was collected by studying literature on how. Page 46 all motors north america water franklin electric. Y2 series three phase induction motor i asynchronous motor y2 series three phase asynchronous motor is a kind of totally enclosed fancooled tefc squirrelcage induction motor. The rotor is often called a squirrel cage because it consists of a circular network of bars and rings that look a bit like a cage connected to an axle. The circuit diagram of load test on 3 phase squirrel cage induction motor. Y2 series 3 phase induction motors are characterized with. The measurements shall be carried out with an instrument conforming to iso 2954 10 hz frequency range. Its main function is to support the stator core and the field winding. How to check the windings of a 3phase ac motor with an ohmmeter. Table 4 references the motor horsepower rating, singlephase and threephase, total effective kva required, and the smallest transformer required for open or closed transformer capacity singlephase or threephase note.
Induction motor testing and evaluation summary as energy costs rise, more emphasis is being placed. The trick is knowing which leads to hold on to and which wires make no difference at all. Reasons to determine motor loading most electric motors are designed to run at 50% to 100% of rated load. Test interphase resistance by disconnecting the leads from each terminal with a flathead screwdriver, then touch any two terminals with the two probes.
These types of motors are known as selfstarting induction motors. Threephase dualvoltage motor insulation resistance testing. A threephase motor converts electricity into mechanical energy via an alternating current provided by three leading power wires. Electric motor testing explained the electricity forum. The motor is supplied from a motor control unit which takes in single phase 220v and delivers three phase to the motor.
Motor overheats motor is single basic electrical tester,check each of the threephase power. Electric motors have had a reputation for being a mix of science and magic. Be careful it can hurt to tangle with a three phase motor. I show all the parts, how they work together, and the pros and cons of each method.
The windings all three in a threephase motor should read low but not zero. Test inter phase resistance by disconnecting the leads from each terminal with a flathead screwdriver, then touch any two terminals with the two probes. Sep 10, 2018 i show in detail three different methods for powering a three phase motor with single phase power. The 12lead induction motor is very similar to the ninelead motor. The basic steps in ascertaining the health of a threephase ac motor are given below.
The ninelead threephase induction motor is the most popular motor for industrial use. This would also include visual inspections, windings tests, brush and commutator maintenance and bearings and lubrication. Hello everyone, i am niko and, in this instructables i will show you, how to rewind and renew old three phase electric motor. How to test a 3phase motor gone outdoors your adventure. An electrical motor is an electromechanical device which converts electrical energy into mechanical energy. A three phase motor converts electricity into mechanical energy via an alternating current provided by three leading power wires. On three phase motors only one phase need be monitored as characteristic fault frequencies will be equally evident in all three phases.
Let us assume that the threephase supply given to the motor has a phase sequence of ryb, then the motor. The process is noninvasive, requiring only that a current transformer ampprobe or current clamp be placed around one conductor of the motor power supply cable. It is powered by electrical energy from the output of a vfd or suitable controller. Jul 06, 2016 testing electric motors doesnt have to be a mystery.
Threephase motors require testing with a multimeter. Key insights into the motor manufacturers view of easa members. Machine performance can be calculated by using average of the phase voltages. The torque developed at the shaft of a 3phase motor is constant, less vibration in.
With the motor at normal operating temperature, the vibration velocity shall not exceed 2. 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. List and describe the more commonly used equipment in. How to check the windings of a 3phase ac motor with an. The most common failure mode of a 3 phase ac motor is burnt winding or shorted winding leading to the damage of the motor. Schematic diagram for load test on three phase induction motor 3 phase variac to limit the starting current of the motor ammeter to measure the current drawn by the stator. For most shore facility applications, this is the case. The rotor is either a wound type or consists of copper bars shortcircuited at each end, in which case it is known as squirrelcage rotor. Often it is required to test the winding of the 3 phase windings with the aid of a multimeter or ohmmeter to determine whether the motor is still good or burnt or shorted. Apr 24, 2017 a three phase motor has two main parts.
The first thing to do before testing the windings of the motor is to remove the links linking terminals w2u2v2 and the disconnect the motor from supply l1, l2, l3. So when a motor fails to operate it may not be obvious what the problem is. Basics, maintenance, and diagnostics vii contents continued page 4. Be careful it can hurt to tangle with a threephase motor. How to test a threephase motor with a megger hunker. How to test a 3 phase motor windings with an ohmmeter. Differentiate between the various types of generating electric power stations. For three phase motors, connection type is either star y or delta ac motor winding continuity test using a multimeter, check the continuity of motor winding from phase to phase u to v, v to w, w to u. Single phase magnetic induction motor with exposed rotor and coil after all, motors are always designed to carry out specific tasks. Terminal markings and internal wiring diagrams single phase and polyphase motors meeting nema standards see fig. An induction motor not powered by a vfd typically has utilitysupplied power at its terminals. Consider the working of a motor for a better understanding of these indicators. It ranges from fractional to hundreds of horsepower. Covers principles of threephase motor starters, part winding, reversing, jogging, alternator principles and operation.
The smaller the motor, the higher this reading will be, but it should not be open. Testing a three phase electric motor without a trip down to the repair shop requires a cautious approach, but happily all you need to start with is a voltohmmeter and some simple hand tools. Ensure the terminal for power supply is in good condition. Instruments connected in the circuit serve the function indicated against each. A successful salesman for general electrics motor division once remarked to one of your instructors that, when asked by a customer how a motor. One bench mounted multirange dc power supply psw 2504. It is also used to power large motors and other heavy loads a threewire threephase circuit is usually more economical than an. Let us assume that the three phase supply given to the motor has a phase sequence of ryb, then the motor. Threephase dualvoltage motors are used for most daytoday operations in todays industrial plants. 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. The basic idea of an electric motor is to generate two magnetic fields. Nov 27, 2019 an electrical motor is an electromechanical device which converts electrical energy into mechanical energy. Maintenance manual for three phase induction motors 5100 north ih35 round rock, tx. When the test is performed on other than threephase power, the equations.
Industries of today use threephase motors widely in highpower applications. The design of y2 series induction motor absorbed the advanced technology of electric motors around the world. The basic diagram view a shows a circle with two leads labeled t1 and t2. In electrical engineering, threephase electric power systems have at least three conductors carrying alternating current voltages that are offset in time by onethird of the period. A multimeter terminals placed across this matrix of terminals will indicate the following readings for a good 3 phase motor. Checking spindle motor windings how to spot bad windings in. The motor is supplied from a motor control unit which takes in single phase220v and delivers three phase to the motor. Gives recommended maintenance practices for large ac motors. Just as in the three phase motor diagram, the motor shows the power supply lines as being identified with the t. For this motors, we require three phase power supply, whereas thus three phase. If any one value is less than normal, the motor is shorted.
This is the most common type of motor, due to its low cost, easy maintenance, robustness, overloading and wide range of rotating speed. Once you have tested a few 3 phase motors, the process will come easily. Power supply test for three phase motors, the expected voltage for a 230400v system is 230v phase to neutral and 400v between each of the three phase supply lines. The locked rotor test is made at 15 hz to minimize the errors due to saturation and skin effects. How to test three phase ac motors learning electrical.
If the motor is not in operation over three months, add grease to each bearing per lubrication nameplate. Determine the motor parameters and the total core, friction and windage losses. For this motors, we require three phase power supply, whereas thus three phase power must be supplied in a sequence. Testing a 3phase motor is as simple as holding the leads of a volt ohmmeter.
Check that the correct voltage is applied to the motor using a multimeter. Threephase power, introduced by inventor nikoa tesla, uses a polyphase system of alternating current to supply power to large motors and motor control systems. We look at different motor types, methods for testing them, which megohmmeters to. Insulation resistance test should be performed once every three months.
Threephase electric power is a common method of alternating current electric power generation, transmission, and distribution. Motor vibration shall be measured in a triaxial direction, i. Thus, a 10horsepower hp motor has an acceptable load range of 5 to 10 hp. If you are searching for rewinding of one phase motor you can find it here. The stator consists of a ring with three pairs of coils, evenly spaced around the rotor. It should be noted that the scope of motor testing depends upon the motor type and size, this being indicated on the inspection forms. Page 46 all motors motor maintenance franklin electric. First you should put on safety glasses and shut all electrical connections. Simple steps to electric motor maintenance r baker. These motors run conveyor belts, pumps, fans, and many other applications. Other induction motors covered are multispeed, multimode, and wound rotor motors. A successful salesman for general electric s motor division once remarked to one of your instructors that, when asked by a customer how a motor. The synchronous motor and the brushless dc motors are also covered.
Other motors that are included are 1phase induction motors, permanent synchronous motors and synchronous reluctance motors. Y2 series 3phase induction motors are characterized with high efficiency and energy saving, large starting torque. The three phase induction motor carries a three phase winding on its stator. Testing and commissioning procedure for electric motors eep. The rotor will constantly be turning to align its magnetic field with that of the stator field. The windings all three in a threephase motor should read low but.
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