The voltage stress placed on a motors insulation due to high peak voltages and shortrise times that occur when the motor is driven by a vfd. To effectively test the motor, you must disconnect the field coils where possible. Motor testing equipment newer more contemporary instruments make testing even easier. Electric motor testing explained the electricity forum.
How to check a motor armature for damaged windings groschopp. Use the schematic and take readings of all of the windings. Evaluating and measuring the amps and voltage per phase when a motor is running, as well as rotor bar tests. Technicians should perform a series of tests on an electric motor during routine preventive maintenance or before replacing it.
Lecture 6 three phase induction motors cairo university. The megger insulation tester is essentially a highrange resistance meter ohmmeter with a builtin directcurrent generator. Consult the motor schematic or a diagram of the motor s windings and use the meter to measure the resistance of the windings. The baker awaiv is the result of more than 45 years of experience in the design and manufacture of motor winding testers.
Figure 3typical scale on the megger insulation tester. This standard provides the basic test procedure for evaluating the. Ieee std 1122004, ieee standard test procedure for polyphase. Model repair specifications for low voltage induction motors. Electrical insulation for hightemperature, cryogenic, and.
The following series of repair documentsthe service center evaluation. Review of electrical tests to assess motor windings format. Reverse side of card at right is used to record the test data. Fluke 1507 motor insulation and low ohm testing duration. Troubleshooting with insulation resistance test instruments. Easa aemt study of motor repair impact on efficiency. Review of electrical tests to assess motor windings. Winding analysis can also be utilized as a powerful troubleshooting tool. Topics include test voltage, procedure, frequency and when to perform the various tests. Threephase dualvoltage motor insulation resistance testing.
Testing the state of the windings by the winding resistance and insulation. The megger insulation tester is a small, portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. Electrical and motor machine shop safety procedures. Ieee standard 432000, recommended practice for testing insulation resistance of rotating machines, recommends the insulation test voltage to apply, based on winding rating, and minimum acceptable values for electric motor windings. The display will be zero if the winding is grounded. Methods of rewinding testing the new winding testing of armature.
Isbn 07389785 ss95211 no part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. This prevents testing coiltocoil insulation resistance for all six coils and their combinations. There is much discussion in the industry about how to properly electrically test ac stator and wound rotor windings. How to properly test ac stator and wound rotor windings. All testing used the losssegregation method at no load and full load, which allowed for detailed analysis. Mar 29, 2019 check that the windings are not open or blown.
Read online iec standards for variable speed drives and motor winding. These tests can be conducted with the help of an advanced winding analyzer awaiv and a baker d65r, depending upon motor type. 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. Understanding insulation resistance testing pdf 0712. Nov 01, 2012 to check the condition of the armature windings, the armature will probably have to be removed from the motor. Checking spindle motor windings how to spot bad windings in. The comparative environmental impacts of motor rewinding vs.
The tester analyzes the electric motor fast and reliably. All baker awaiv testers, which include 2, 4, 6 and 12 kv models, are fully compliant with industrystandard ieee motor test recommendations. Pdf winding design, modeling, and control for polephase. Electric motor testing is usuallly the first thing to be sacrificed when cutting back on operational expenses. Motorguard is an automatic insulation resistance tester that monitors and protects criticalduty motors. Pdf stator winding tests are usually performed to detect problems in the electrical insulation.
If the turn insulation fails in a formwound stator winding, the motor will likely fail in a few minutes. The ieee 112 method b ieee 112b method of efficiency testing was used. Insulation resistance testing is performed when troubleshooting electric motors and related equipment. Evaluation ofmarkets andefficiency offractionalpolyphase motors. Electrical and motor machine 61 electrical and motor machine shop safety procedures this section has been formulated to set guidelines for all electrical work performed by this department. May 18, 2010 hightemperature tools and drilling this presentation does not contain any proprietary. Get motor rewinding procedure pdf file for free from our online library pdf file. Low voltage tests on formwound stators, such as inductance or inductive impedance tests, can detect if the turn insulation is shorted, but not if it is weakened. Understanding insulation resistance testing aemc instruments. Understanding insulation resistance testing pdf 0712 technical assistance 800 34391. Industrial motor testers electric motor winding test. The complete guide to electrical insulation testing.
To do this for delta connected 9lead motors, remove the wirenuts from 4 and 7, 5 and 8, and 6 and 9. The effect of repairrewinding on motor efficiency easa. Pdf testing and analysis of induction motor electrical faults. For instance, test equipment such as flukes 438ii power quality and motor analyzer uses algorithms to analyze not only threephase power quality but also torque, efficiency and speed to determine system performance and detect overloaded conditions, eliminating the need for motor load sensors. Table 2 provides the test results for the 30 kw motor when tested at 50 and at 60 hz. The measurement of the winding resistance is commonly the first test performed.
These motors run conveyor belts, pumps, fans, and many other applications. Offline tests that are done during a shutdown insulation resistance, motor circuit analysis, surge test, hipot test, growler, visual inspection. If, during the procedure for identifying motor terminals, the ohmmeter displays a blank readout during any test, there is probably a defective winding. This article describes how the following standards address these questions. After that, the interturn short circuit is the immediate. Checking spindle motor windings how to check for bad windings in a spindle motor to check your spindle motor for bad windings, you can use several different methods.
The purpose of this manual is to provide direction and to the greatest extent possible, to assure a safe work environment for all electrical employees. Motors are susceptible to the gradual failure of their insulation resistance. The thick wire gauge winding is main winding and thin wire gauge winding is starting winding. Oftentimes, acceptance testing of motors is specified. If you open the single phase motor, you will find out that your motor have two types of winding in which one is made from thick wire gauge and one thin. However, if the motor design has external brush holders, you can unscrew the brush caps and remove the brushes. Winding design, modeling, and control for polephase modulation induction motors article pdf available in ieee transactions on magnetics 492. As always, make sure to disconnect all power from machine before doing anything. We highly recommend using a qualified, experienced vendor like tigertek for your spindle motor. If the computer simply by connecting to the detects a weakness in the insulation, preprogrammed motor, the test is interrupted, the operator is ensuring a higher degree of alerted, and all test parameters at automatic or manual reliability in testing procedures. Automated testing with the push of a button makes motor testing easy and available for personnel who are not experts, and who do not use a motor tester all the time. Using a phase rotation meter on your newly bought motor or pump can ensure new or refurbished motors are good before being installed, or can monitor existing motor health for developing problems. Threephase dualvoltage motor insulation resistance testing threephase dualvoltage motors are used for most daytoday operations in todays industrial plants.
Improving motor and drive system performance energy. Aug 06, 2017 fluke 1507 motor insulation and low ohm testing duration. Read online now motor rewinding procedure ebook pdf at our library. The itig ii winding analyzer will take the guess work out of your maintenance processes when it comes to the testing of insulation systems. All books are in clear copy here, and all files are secure so dont worry about it. This means that the motor is an essential part of any pump. Figure 4typical record of insulation resistance of a mill motor. The rotor winding terminals are connected to three slip rings which turn with the rotor. Download iec standards for variable speed drives and motor winding. When the observed temperature rise of the motor winding does not vary more than 2f. Consult the motor schematic or a diagram of the motors windings and use the meter to measure the resistance of the windings. Induction motor testing and evaluation summary as energy costs rise, more emphasis is being placed on determining the health of large inductive motors.
The meter should not show an open or a short when a winding leg is measured. But smart companies understands is that what this means for maintenance programs is billions of dollars of lost revenue through increased motor repair costs, downtime, and waste in industrial and commercial companies. The slip ringsbrushes allow external resistors to be connected in series with the winding. Electrical insulation for hightemperature, cryogenic, and other harsh environments hightemperature motor windings for downhole pumps used in geothermal energy production matthew hooker composite technology development, inc. Curve b shows same values corrected to 20c see page 22, giving a definite downward trend toward an unsafe condition. Each winding leg should have some small resistance reading. But this identification can only be done by disassembling the motor. Ieee std 1122004 revision of ieee std 1121996 ieee standard test procedure for polyphase induction motors and generators sponsor electric.
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