Then, use a flat head screwdriver to pry open the tabs on the brush pads, and then cut through the wires and pull them out by hand. The stator core is made up of many thin metal sheets,called laminations. A new method for stator core repair reduces core losses and. The tests shall be done at a flux density of 85,000. In addition to conventional squirrel cage rotor testing methods such as the growler test, also covered will be techniques such as the use of a core loss tester, high current excitation, and spectrum analysis of vibration. Evaluate the impact that physical damage to the stator core has on efficiency. Method of evaluating loss distributions within the electric motor for different operating conditions in collaboration with university of wisconsin madison development of stator thermal model validated against published data parameter sensitivity study of thermal design factors for motor stator. The stator is the outer body of the motor which houses the driven windings on an iron core. This shop order number should be listed on the repair invoice. The stator core is made up of a stack of round prepunched laminations pressed into a frame, which may be made of. The steel laminations used in the stator core of electric motors and generators are electrically insulated from one another to reduce eddycurrent losses.
Abstract the steel laminations used in the stator core of electric motors and. The rotor body is the rotating part of the motor and is made of a steel core with aluminium windings. Fletcher moorland ltd electric motor repair specification. An investigation into a new method to repair motor cores and. Easa aemt study of motor repair impact on efficiency. The insul core solutions process provides the ultimate opportunity to potentially restore the core plate without dismantling the core, saving labor, eliminating the chance of unsatisfactory restack results and the possibility of scrapping an expensive piece of electrical equipment. Prior to the thermographic survey, the damaged sections of the core were repaired and. The power transmission system is integrated with riserpipes. Diagnostics of rotor and stator problems in industrial induction motors by fang duan b. Past, present and future john petro petro and associates consultants. Watch the entire electric motor rewind process with this video from the gibbons engineering group workshop in essex. High power ac motors are typically inductive in design.
Sources of stress in the machine that lead to stator winding deterioration. Rotor is usually made as squirrelcage, and it is inserted in stators hole. As a result, the motor rotates in the direction of the resultant torque. They are punched and clamped together to form a hollow cylinder stator core with slots as shown in figure 1. A systematic approach to ac motor repair ansieasa ar100 provides best practices for mechanical repair, electrical repair including rewinding, and testing that help apparatus rebuilders maintain or enhance the performance, reliability, and energy efficiency of ac and dc motors and generators. The coils are preformed and cured before insertion into the stator slots.
This article presents a basic explanation of electric motor construction and. Now, a 500 hp stator core with a known watt loss can be compared to that of a 5 hp stator. Many sections are mainly applicable to the lvmv induction motor equipment and many others are applicable to either synchronous or dc motors. The effect of repairrewinding on motor efficiency easa. When, during the course of a repair, a motor or generator stator is found to have. Electric motor electric motor construction of induction motors. Repair, evaluation, maintenance, and rehabilitation remr research program identify the problem area under. Inplant service for turbine rotors including rso testing, insulation resistance testing, impedance testing and shutdown work. Pdf it is necessary to present a motor repair specification for the repair of. Getting to the core of your generator stator problems. Making generators at lower cost has had a significant negative impact on the current fleet of newer generators, units less than about 30 years old. This checklist incorporates all range of motors equipment.
This forms an axial motor stator that, when combined with coils and a permanent magnet rotor, forms an electric machine that can be used as either a motor or a. Insulcore solutions electric motor core repair msc. Harley and yao duan georgia institute of technology november, 2009. Model repair specifications for low voltage induction motors. The stator core has slots that are filled with copper windings. We use only the best materials available and can rewind a wide range of stators. Maughan, president maughan generator consultants schenectady, ny, usa abstract. This presentation will discuss how to perform a stator core test using a loop test. Here are tips on how to find the problem, fix the rotor, and get the motor running again. Since inception, lexsco has performed core loss tests in a variety motor repair shop environments. Electric motor repair, model repair specifications for low voltage motors, and. Getting the rotor back up and running machine design. Another integral part of the stator is the stator core which is supposed by the stator frame.
The stator core is built of sheetsteel laminations that are supported in a frame. A new method for stator core repair reduces core losses. Diagnostics of rotor and stator problems in industrial. Tutorial how to rewind electric motor part one youtube. Pdf evaluation of induction warming stator cores for coil removal. They are insulated with resinrich glass and mica paper tapes.
The steel laminations used in the stator core of electric motors and generators are. The stator frame consists of laminations of silicon steel, usually with a thickness of about 0. Record stator current, stator voltage, and field current for the complete acceleration period. In this instructables i will show you, how to rewind and renovate old electric single phase electric motor. 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. In a singlespeed threephase motor design, the standard stator has three windings, while a singlephase motor typically has two windings. Stator the stator is made up of several thin laminations of aluminum or cast iron. How to test and assess stator core condition using a loop. Inspection and test procedures for rotating machinery. 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. A second goal was to identify procedures that degrade, help maintain or even improve the efficiency of rewound motors and prepare a good practice guide to maintain motor efficiency part 2. How capacitor discharge ignition cdi system works and.
Traditional design of cage rotor induction motors ronald g. For a long service life, the groundwall must meet the. Mmf drop along stator teeth, rotor teeth, stator core and rotor core. Pdf electric motor repair for low voltage induction motors in pwm. Ieee std 1122004 revision of ieee std 1121996 ieee standard test procedure for polyphase induction motors and generators sponsor electric. Introduction three phase motors can be classified into two types. Ger4212 ge generator rotor design, operational issues. Those common questions can be answered by checking the stator core condition. Electric motor construction of induction motors britannica. This particular stator had suffered a failure resulting in the burning out of a series of iron packs located throughout the turbine side of the stator. The stator core is fixated inside the motor house and is made of laminated electrical steel sheets.
This will assure that the core has not been damaged during repair. Some sections may explain explicitly between the three. Turbine field rotor repair and rebuilding including retaining ring inspections, rotor field cleaning, testing, rewind and recondition. Groundwall insulation failure usually triggers a ground fault relay, taking the motor or generator offline. A new method for stator core repair reduces core losses and repair time abstract. Skin effect may not be neglected in linestart motors when assessing the starting, or breakdown torque. Winding ground faults in large synchronous hydrogenerators and motors, by. Technical bulletin core loss testing theory ird balancing. When a bearing failure results in friction between the rotor and stator, or a ground fault occurs.
This way we can evaluate your stator and make sure it is repairable before you send. Among other actions, the procedures followed by highquality shops include conducting a stator core test before and after winding removal, as well as confirming that the core has not been damaged during the repair process. Motor driven equipment often provide core capabilities essential to business success and to safety of equipment and. For large motors, the practice is to wind the stator with formed coils figure 9. For over 20 years ricky stator has been rewinding modifying and repairing stators for the powersports industry. Plant engineering a systematic approach to ac motor repair.
A new edition of the only american national standard for repair of motors and generators ansieasa ar1002010. Easa aemt study of motor repair impact on efficiency thomas h. A core loss test is to be carried out on every stator to be rewound. Visually inspect for signs of axial and radial movement. The core is constructed in the form of laminations and the material used for the same is either magnetic iron or steel alloy. The laminations are insulated from each other usually by a varnish layer.
A final objective was to attempt to correlate results obtained with the running core loss test and static. Lamination is necessary since a voltage is induced along the axial length of the steel as well as in the stator conductors. Coils of insulated wires are inserted into these slots. The ultimate solution for stator core and lamination repair. Navsea motor repair manual, identified that these methods. Whitelegg now offer an unrivalled range of equipment to the electric motor repair industry. An inductive rotor is constructed by laminating iron disks together to form the central core of the rotor.
Ieee std 1122004, ieee standard test procedure for. Electric motor repair equipment whitelegg machines. A capacitor discharge ignition consists of several parts and is integrated with the ignition system of a vehicle. Ac motor repair report form page 39 appendix f mechanical inspection for motors as completed page 40. It also will explain how to analyze the results, providing information about the associated equipment, tips for repairing core damage and explain other alternatives for stator core. To rewind an electric motor, remove the motors outer housing and use your hands to pull the armature out of the stator. Thus the stator groundwall insulation is critical to the proper operation of a motor or generator. An outside repair firm was hired by the customer to conduct all necessary repairs on this stator. The foremost parts of a cdi include the stator, charging coil, hall sensor, flywheel and the timing mark. Repair the hydro generator by cutting out stator winding barscoils. How different burnout temperatures affect stator core losses.
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