Category: Electric motor problems and solutions pdf

Electric motor problems and solutions pdf

All electric motors have their predetermined life span, typically ranging from 30, to 40, hours. However, this is dependant on proper maintenance - without which they are likely to break down much quicker.

Understanding the top five causes of motor failure, as well as the steps that can be taken to reduce the risk of these failures occurring will give your motor the best chance of achieving its maximum possible service life. Electrical overload or over-current is caused by an excessive current flow within the motor windings, exceeding the design current which the motor is able to carry efficiently and safely.

This can be caused by a low supply voltage, resulting in the motor drawing in more current in an attempt to maintain its torque. It can also be a result of short circuited conductors, or an excessive voltage supply. Possible solution: Electrical overload can be prevented by installing effective over-current protection which will detect overcurrent and interrupt supply.

The most common cause of motor failure, and arguably the most difficult to overcome, is low resistance. Low resistance is caused by the degradation of the insulation of the windings due to conditions such as overheating, corrosion, or physical damage.

Solving Automotive Electrical Problems

This leads to insufficient isolation between the conductors or motor windings, which can cause leakages and short circuits, and eventually motor failure. Possible solution: The insulation should be regularly inspected for signs of wear, and replaced before low resistance is able to cause failure. Overheating can be caused by poor power quality, or a high temperature operating environment.

Possible solution: It is critical that the motor is kept as cool as possible, ensuring the operating environment is kept cool if possible will help prevent breakdowns. Contamination from dust, dirt and chemicals is one of the leading causes of motor failure.

Foreign bodies which find their way inside the motor can dent bearing raceways and balls, leading to high levels of vibration and wear. Possible solution: Preventing contamination is relatively easy. Keep work areas, tools and fixtures as clean as possible to help eliminate the chance of contamination entering the motor. Also, when laying out the workspace, try to position motors away from grinding machines which produce large amounts of contaminants.

Vibration can lead to many issues with the motor, and can eventually cause the motor to fail prematurely. Vibration is often caused by the motor being positioned on an uneven or unstable surface. However, vibration can also be a result of an underlying issue with the motor, such as loose bearings, misalignment, or corrosion. In order to reduce vibration, ensure that the motor is positioned on a flat, stable surface.

If vibration still occurs, check for signs of wear, as well as loose bearings or misalignment. Consider contacting a specialist if the source of vibration cannot be identified. For more information and solutions, our dedicated couplings and drives division is perfectly placed to offer you expert advice in application design and coupling and drive selection, making sure that your application reaches its full potential.

Free delivery available Worldwide distribution Same day despatch Easy returns. Electrical Overload Electrical overload or over-current is caused by an excessive current flow within the motor windings, exceeding the design current which the motor is able to carry efficiently and safely. Low Resistance The most common cause of motor failure, and arguably the most difficult to overcome, is low resistance.

Contamination Contamination from dust, dirt and chemicals is one of the leading causes of motor failure. Vibration Vibration can lead to many issues with the motor, and can eventually cause the motor to fail prematurely. Your troubleshooting guide to electric motors.Stage Bangalore — Calculate the rotor I2 R losses using the following data:? What are the two main advantages of application of a variable frequency drive in an induction motor other than accurate speed regulation?

Two of the main advantages are i High operating power factor ii Energy savings during part load operation for longer duration of time. Why the accuracy of the slip method is limited? The largest uncertainty relates to the accuracy with which manufacturers report the nameplate full- load speed.

Manufacturers generally round their reported full-load speed values to some multiple of 5 rpm. While 5 rpm is but a small percent of the full-load speed and may be considered as insignificant, the slip method relies on the difference between full-load nameplate and synchronous speeds. The actual power measured was 13 kW. Estimate the percentage loading of the motor? List down important factors required for successful implementation of variable speed drives for any application Ans.

The important factors required to be considered for successful implementation of VSD are:. List down various methods available for determination of percentage loading of an induction motor? The following methods are available for determination of percentage loading of induction motors with their own advantages and disadvantages:. By input power measurements 2. By line current measurements 3. Slip method 10 Comment on estimation of efficiency of 3 phase induction motor at field?

It must be clear that accurate determination of efficiency is very difficult. From rated current value, I2R losses are calculated. What are the points to be considered while evaluating the efficiency of motor?

In view of this, for selecting high efficiency motors, the following can be done : a When purchasing large number of small motors or a large motor, ask for a detailed test certificate. If possible, try to remain present during the tests. This will entail extra costs. What is the information needed to evaluate energy savings for variable speed application?

Method of flow control to which adjustable speed is compared: o output throttling pump or dampers fan o recirculation pump or unrestrained flow fan o adjustable-speed coupling eddy current coupling o inlet guide vanes or inlet dampers fan only o two-speed motor.Use this resource to troubleshoot your AC motor. Narrow your search by selecting motor type, gearbox, voltage, and phase options for your desired motor. Select a dominant variable: choose one of the three parameters to narrow your search.

The selected variable determines which slider bar you will be able to manually move. Use the slider corresponding to your dominant variable to further narrow your motor selection. The other sliders will automatically move to show available ranges based on the range of your selected variable. Results will upload as your search criteria changes. If you have any questions regarding your results or how to use the search tool, you can chat with us using the green tab on the left-hand side of your screen.

Note: Groschopp Universal motors are custom built to fit your application so no additional options are available to narrow the search.

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Selecting the Universal motor type will prompt a message taking you to the Universal product page. One of our team members would be happy to help. Contact us at or by email at sales groschopp. You can also chat with us using the green tab on the left side of your screen. Groschopp Universal motors are custom built to fit your application so no additional options are available to narrow the search. Standard frame sizes and motor features can be found on the Universal page.

Selected Products. How did you hear about us? Motor Fails to Start Upon Initial Installation Motor is wired incorrectly Refer to the wiring diagram to verify the motor is wired correctly.

Power supply or line trouble Check the source of power, overload, fuses, controls, etc. Stator is shorted or went to ground Motor will make a humming noise and the circuit breaker or fuse will trip Check for leaks through the coils. If leaks are found, the motor must be replaced. Motor overloaded or jammed Inspect to see that the load is free.

Verify the amp draw of motor versus the nameplate rating. Capacitor on single phase motor may have failed First discharge the capacitor. To check the capacitor, set the volt-ohm meter to RX scale and touch its probes to the capacitor terminals. If the capacitor is OK, the needle will jump to zero ohms, and drift back to high. Steady zero ohms indicates a short circuit; steady high ohms indicates an open circuit.

Load increased Verify that the load has not changed and the equipment has not gotten tighter.Keep electric motors running at peak performance! Essential for anyone who needs to buy, install, troubleshoot, maintain, or repair small to industrial-size electric motors, this practical guide contains new information on three-phase motors along with coverage of the latest test instruments.

Drawing on his more than 40 years of experience working with electric motors, expert author Augie Hand provides a wealth of tested procedures to pinpoint and correct any kind of issue. He'll help you decide whether to replace a motor, take it offline for repair, or repair it in place--decisions that can reduce down time.

End-of-chapter questions reinforce the material covered in the book.

5 Causes of Motor Failure and How to Prevent Them

Quickly and accurately diagnose electric motor problems and find effective solutions with help from this fully updated classic. Skip to main content. Start your free trial. Book Description A fully up-to-date, hands-on guide to electric motors Keep electric motors running at peak performance! Electric Motor Maintenance and TroubleshootingSecond Edition covers: Troubleshooting and testing DC machines AC electric motor theory Single-phase motors Three-phase induction motors Troubleshooting less common motors, including synchronous, two-speed one-winding, and multispeed Test instruments and services Show and hide more.

Table of Contents Product Information.Worked Examples in Electrical Machines and Drives discusses methods in predicting and explaining electromechanical performance of several devices. The book is comprised of seven chapters that sequence the examples at increasing levels of difficulty. Chapter 1 provides an introduction and reviews the basic theories. The second chapter covers transformers, and the third chapter tackles d.

Chapter 4 is concerned with induction machines, while Chapter 5 deals with synchronous machines. The book will be of great use to students and instructors of schools concerned with electronic devices such as in electrical engineering, and can help enrich their lectures and practical classes.

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electric motor problems and solutions pdf

Search for books, journals or webpages All Pages Books Journals. However, due to transit disruptions in some geographies, deliveries may be delayed. View on ScienceDirect. Authors: John Hindmarsh. Editors: P. Imprint: Pergamon. Published Date: 1st January Page Count: Flexible - Read on multiple operating systems and devices. Easily read eBooks on smart phones, computers, or any eBook readers, including Kindle.

Institutional Subscription. Free Shipping Free global shipping No minimum order. Machines 3. Machine 7. Machine Drive 7.Get Great Electric Motor Reliability.

electric motor problems and solutions pdf

Electric motor failures can be due to mechanical component failure or electrical circuit failure. To achieve long motor life in wet environments, like a dairy processing plant, standard motor construction and standard water ingress protection are insufficient. This article presents a bunch of bullet points from a presentation by Mark Gurney of Victoria, Australia.

Mark spent three years overcoming electric motor failures in the dairy product business he works for. One user in the beverage industry went as far as sending brand new motors to the rebuilders. They removed the standard ZZ shielded bearings that were filled with lithium grease and replaced them with 2RS rubber shielded bearings and filled with polyurea grease.

This modification lifted motor life from 12 months to 36 months. Improve the shaft to housing sealing. A weak point that fails quickly is the shaft seal. Failure can be due to vibration, rubbing, contamination working its way between shaft and seal. Installing a better seal design with a slinger improves bearing life. One such seal is the Stefa Seal. Put key motors on a vibration analysis round. Record the new bearing signature and then trend changes in bearing behaviour to forewarn you of coming problems.

electric motor problems and solutions pdf

Do preventative maintenance testing on the entire motor circuit. Equipment is available to test motor integrity when the motor is off-line. The test unit sends a low voltage signal through the circuit and indicates faults with resistance, impedance, insulation, internal wiring and more.

Over crimping of connectors to the cable core is a common problem, even with new motors, and produces high resistance. Thermography the isolators, connectors and drives. Thermal imaging will identify hot spots in operating circuits fast.

Is the motor compatible with the Variable Speed Drive? A VSD can alter the power characteristics but the motor may not be designed for it. There have been winding insulation failures and internal short circuits across wires and cores due to frequency cycling. Motor terminal connections can vibrate loose over time.

The nuts on the connection studs inside a terminal box are often not torqued down well. The electricians had only ever tightened the top nuts. They had copied what someone had incorrectly shown them years ago.

The answer to this problem is to write a thorough terminal connection procedure and train the electricians to follow it. Use detailed explanations and pictures of the right way to terminate and make it standard practice to train every electrician in the right practices. Use non-corroding silicon sealant for sealing. There is a special grade of silicone sealant to use on electrical equipment.

Do not use any other grade of silicone sealant because the vapours given off corrode metal electrical components. Disclaimer: Because the authors, publisher and resellers do not know the context in which the information presented in this article is to be used they accept no responsibility for the consequences of using the information contained or implied in any articles.InspectAPedia tolerates no conflicts of interest.

We have no relationship with advertisers, products, or services discussed at this website. In this article we provide a diagnostic guide to determine and repair problems with electric motors. The page top photo was taken of of an oil burner electric motor not an air conditioning blower fan motor or pump motor, but you'll see that all of these electric motors look a lot alike. At left our photo illustrates the motor as typically found in a direct-drive HVAC blower or air handler assembly.

More about this air handler fan i. Watch out : if you are not trained in safe electrial wiring and test tool use you should not fool with electrical motors or wiring. You could be shocked or killed.

While our page top photo shows the red reset button most clearly, the reset button on the motor at left may be harder to spot. Sometimes the reset button on an electric motor is hard to find, and sometimes there is no reset button! Fatal Shock Hazard Warning : Inspecting electrical components and systems risks death by electrocution as well as serious burns or other injuries to the inspector or to others. Do not attempt these tasks unless you are properly trained and equipped.

Before discussing how to diagnose air conditioner or heating system electric motors let's be sure we know what motor parts might be involved.

electric motor problems and solutions pdf

Or skip right to Table A if you prefer. Photo: electric motor on a modern oil burner. The electric motor has quite a few parts if examined in detail, switches, wires, possibly capacitors, oiling ports and more, but there are four basic parts to every HVAC electric motor:.

In addition to the basic electric motor components above there are two other features to know about when troubleshooting a motor. The blue oval marks the motor's rotating speed - RPM - this is a high speed oil burner. Older oil burners and equipment motors run at RPM. Some HVAC equipment uses a variable-speed electric motor. The green rectangle marks other useful data in the data tag for this motor, made by Emerson Electric in St.

Louis MO. These data are helpful when diagnosing electric motor problems: using a DMM or VOM we can detect unusual current draw above that 2. The motor's model number SD55GYJTK in this example is useful when replacing the motor or contacting the manufacturer for assistance.

An Electric Motor Time Rating designation is specified as CONT continuous duty - this motor is able to run continuously without damage or overheating under normal conditions. A temperature rating 40C and other data are given as well, including an explanation that this motor is. This motor's data tag also includes oiling specifications indicating the required lubrication schedule, discussed.

Watch out : when buying replacement electric motors, fuel units, and blower fan assemblies to be sure they all are compatible. For example on oil fired heating equipment, the oil burner fuel units the mechanical heating oil pump driven by the oil burner electric motor via a coupling can be purchased as CW or CCW devices. All three components have to be designed to rotate in a common direction:. If the fuel unit is not rotated in the proper direction the heating appliance won't run - it won't receive fuel, and the driving motor and coupling parts may be damaged.

If a squirrel cage blower fan on an oil burner or inside of an air handler is spun backwards it will not move much air and equipment will not function properly. The start switch connects power to the start winding to start the motor spinning. This feature is necessary because depending on the position in which the rotor stopped when the motor last turned off, the rotating electrical field created by the run winding can't start the motor. A trained service technician may sometimes diagnose a failed start winding or failed start switch centrifugal switch by spinning the motor manually potentially dangerous!

If the motor keeps running we suspect a bad start winding or bad start switch see diagnostic table details. Power was already connected to and remains connected to the run winding. So if the motor will start but won't keep running, we suspect a bad run winding or bad wiring to the winding.

For electric motors used in most HVAC applications motor full speed is usually or rpm, though some equipment may use variable speed motors as well. The centrifugal switch will open "throwout" at about rpm for a rpm electric motor, and the centrifugal switch will open at about rpm for a rpm electric motor.


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