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Tag Archive: electric motors

1. Why Would I Keep My Old Motor?

   October 20, 2015 8:39 am Comments Off on Why Would I Keep My Old Motor?

   

   The current push in today’s world is to upgrade everything to a more energy-efficient state. This is true for cars, appliances, and electric motors.

   If you are deciding whether to keep your old motor or to replace it with a new one, please consider the following:

   Production/Operation Downtime

   Motor replacement requires an associated amount of pre-planning or downtime in operation or production that could be avoided by simply keeping the working motor you already have. Small repairs often take less time than ordering and installing a new motor, which would equal more downtime.

   By pre-planning for the replacement, the best solution — a combination of motor efficiency, cost and performance — can be determined and ordered to avoid rush charges or costly mistakes made when under the pressure of a machine being down.

   Starting Torque

   The starting torque for old motors is generally much higher than starting torque for new motors. This means that replacing your old motor would likely also require installing a new drive into your current machine or equipment, which may not be the most convenient option.

   Often an updated control scheme, as simple as a soft-start, will help reduce the cost of electricity consumed on start-up while maintaining the torque required for the machine.  If a new high efficiency motor is required, careful consideration to starting torque or full load torque may determine that the motor and drive be sized as much as 150% larger in order to achieve the same results as old wound rotor motors.

   Cost

   Although replacing your old motor with a newer motor—particularly one with a more efficient motor—may save your company money in operational costs, it may still not be the most cost-effective solution for you. Often, the cost of maintenance and preventative care for your current motor is much less than the cost of replacing it with a new one.

   Some operating costs can be saved by adding soft starts or VFD’s which have incentives from the power companies that may be as high as 100% of the cost of the VFD.  Often simple things like not stopping and restarting large motors between 11am and 5pm will reduce your energy costs substantially.

   In addition, if the motor is small or only used sporadically, the energy savings of a new motor may not be significant enough to warrant the upgrade. Simple calculations can be made to determine if a motor upgrade would really be the best option.

   At Renown Electric, we offer a selection of the highest quality electric motors to provide you with the motor you need. We are specialists in motor maintenance and replacement.  Please consult one of Renown’s motor specialists to help you determine the best course of action to optimize both cost and performance.

   If you are interested in keeping your old motor and want to make sure that it is well maintained, download our eBook “Preventative vs. Predictive Motor Maintenance.”

    

2. Prevent Downtime with Renown’s Coast-to-Coast Field Services

   July 15, 2015 9:00 am Comments Off on Prevent Downtime with Renown’s Coast-to-Coast Field Services

   When an electric motor can’t perform to capacity, your company suffers—equipment failure leads to reduced productivity and loss of revenue.

   If your equipment can be brought to a repair shop, a trained technician can help. Unfortunately, many customers find themselves at the mercy of their local technicians’ schedules; in these instances, it’s best to choose a company that’s available when you need them most.

   

   At Renown Electric, our coast-to-coast, around-the-clock service keeps your business up and running at all times. Our team helps diverse companies reduce their down time and get machines in working order quickly.

   Renown provides a variety of field services for your motors, including:

   • Surveys – Renown conducts motor brush surveys to identify and correct motor problems before they become more severe. We also offer modernization surveys to ascertain the most ideal equipment choice for your application.

   • On-Site Machining – When equipment is starting to wear but is too large or cumbersome to transport, we bring our machining capabilities on-site. We have the capabilities to mill, weld, drill, thread, ream, and bore, helping to restore your equipment to run like new.

   • In-Field Rewinding – Rewinding is essential as insulation breaks down over time and under various day to day stresses. Our services include an evaluation of both AC and DC components, the manufacturing and installation of new components such as coils. This new equipment is then tested and verified to the letter of today’s standards.

   • Turning and Undercutting – One method to alleviate excessive wear on machinery (while promoting proper electrical current transfer) is with Renown’s turning and undercutting capabilities—which can eliminate vibration, arcs, and burring as well.

   Remember that these services are available 24 hours a day, 7 days a week—either at your facility’s location or in our advanced 25,000 square foot repair facility. If your equipment has gone down, is lacking in service, or if you’d like to explore ways of expanding and modernizing your current services please contact Renown Electric today.

3. 3 Environmental Factors That Affect Your AC Motor

   June 23, 2015 9:57 am 1 Comment

   Electric motors are marvels of engineering, but they are not invulnerable.

   Of the many hazards that can lead to a damaged AC motor, none are as common as unfavorable environmental factors. Here’s a brief review of some of the more common environmental conditions that will send your electric motor to the repair shop sooner than you anticipated, as well as some general advice on how to keep them up and running longer.

   

   1. Extreme Temperatures

   The most common risk factor for the average electric motor is extreme temperature, either hot or cold. AC motors have optimal temperature ranges for peak operational performance that are determined by their manufacturers after a great deal of testing. So, make sure to adhere to these specifications closely to keep the motors you’re using in good working order. In general, industrial AC motors operate best at ambient temperatures between +40° to -20° Celsius (C).

   In settings where the air temperature will fall below -20° C (or -4° Fahrenheit), you’ll need to make sure your AC motors are properly lubricated. Grease-lubricated bearings will need to be coated with grease recommended by the manufacturer as suitable for low-temperature conditions. Oil-lubricated bearings will need a thermostat-regulated oil-sump heater to warm the oil.

   An overly hot environment, where the air temperature exceeds +40° C (or 104° F), can also lead to short motor life. If a motor must operate under such conditions (and you have no other ambient cooling/ventilation measures), you may need to rewind the motor to a higher class of insulation (or simply choose an oversize motor to begin with).

   2. Altitude

   In terms of harsh environmental conditions, the altitude at which an AC motor must operate is also a major concern. Typically, industrial motors are designed for operation up to an altitude of 1000 meters (3281 feet), where ambient air has less cooling capacity.

   There’s a good rule of thumb for altitude: For every additional 100-meters in altitude above 1000 meters, a motor must be de-rated by 1%. Thus, at an altitude of 2000 meters, a motor would need to be de-rated by 10%. So you should probably choose a motor the next size up.

   3. Poor Ventilation

   An often overlooked environmental factor that can compromise the operation of an AC motor is, simply put, dirty (or salty) air. If you must operate an AC motor in an extremely dirty or salty environment, consider upgrading it to an enclosed model with good ventilation.

   A Totally Enclosed Fan-Cooled (TEFC) motor is probably your best bet in these conditions. TEFC motors use a shaft-mounted fan to blow cooling air over a ribbed frame to dispel heat. Or you could go with a Totally Enclosed Air-to-Air Cooled (which has an air-to-air heat exchanger) or Totally Enclosed Water-to-Air Cooled (which has a water-to-air heat exchanger) motor type.

   With so many variables to consider, one of the best pieces of advice you can get is to discuss your requirements with a knowledgeable professional, who can review all the options with you. That’s where we come in — feel free to contact us today.

4. Aspects of Commutator Skins

   June 1, 2015 9:33 am Comments Off on Aspects of Commutator Skins

   Electric motors are widely used throughout the world, so much so that people often take them for granted. At times, people forget the fact that motors are precision machines prone to occasional breakdown.

   There are various reasons why an electric motor may stop working; most commonly, the issue will be a malfunction with the motor’s commutator.

   Commutators are critical components, as they generate current in windings of the motor. By reversing the direction of this current each half turn, torque is produced; simply put, the commutator is directly responsible for facilitating an electric motor’s spinning operation.

   Unfortunately, there are several issues that can befall motor commutators. If the outer surface, or skin, of the commutator develops a defect, the machine won’t be able to properly transfer a current to motor’s coil.

   Skin defects can be caused by excessive humidity, faulty bearings, and overloading the motor. Common skin defects include erosion and bar markings—these defects will greatly reduce the efficiency of your motor.

   The Solution to Commutator Defects

   

    

   Many preventative practices can help you avoid commutator defects; one such practice is routine physical inspection of the commutator. Inspecting the skin is a great way to assess the commutator’s condition, and at Renown Electric, we’ve created a new resource to help you do just that.

   Aspects of Commutator Skins is a technical bulletin that details the array of issues frequently afflicting motor commutators. With this guide, you will be able to recognize various commutator defects while learning more about the causes of these defects.

   Should you discover a major defect in your commutator, not to worry—Renown Electric is equipped with the tools and expertise needed to return your commutator to peak working condition.

   Learn more about commutator defects by downloading your free copy of Aspects of Commutator Skins today.

   If you have any questions about commutators, or general electric motor repairs, feel free to contact Renown Electric—our customer representatives are available 24 hours a day.

5. Proper Steps for Storing Electric Motors

   April 20, 2015 2:37 pm Comments Off on Proper Steps for Storing Electric Motors

   Fill in the blank:

   The only thing worse than having an electric motor fail, is having the backup motor fail due to improper _______.

   If you guessed the word is “storage,” congratulations—you’re a winner. (OK, you didn’t win anything, but you are very intelligent.)

   An improperly stored electric motor can cause all kinds of problems. Starting with the motor’s exterior, you will likely notice corrosion from moisture and/or problems of fretting corrosion on the rotors. There are a number of other issues that can arise from poor storage practices; fortunately all can be overcome if the correct precautions are taken.

   

   Here are some points to consider in regard to electric motor storage:

   1. Always store motors indoors in a clean, dry, and vibration-free environment. Preferably in a cabinet or closed storage area that is free of insects and airborne debris.
   2. Always remember to pack the bearing cavities with grease for added protection from moisture.
   3. Don’t leave the motor surface exposed to the atmosphere even if it meets the specifications mentioned for storage. Apply a rust inhibitor to the exposed surface and reapply the inhibitor occasionally while in storage. Yes, the motor will require cleaning prior to use. However, compared to replacing the motor or being left without a backup, it’s a small price to pay.
   4. Always store electric motors vertically, if this is not possible, rotate motors quarterly. This avoids creating a small dent in the bearing’s outer race due to the excess weight of the rotor and shaft assembly. This may not seem significant, but it will show up once the motor is placed in service as noise and appear in the vibration signature.
   5. With your bearings packed in grease, you’re set to go, right? Well, no. Periodically turning over both sealed and shielded bearings prevent the grease from settling on one side, which will cause problems later if allowed to happen.
   6. The insulation in the windings can degrade while in storage if the windings temperature falls below 10° F to 20° F above the ambient temperature. Portable heaters or humidifiers may be required.Take a baseline insulation resistance (IR) measurement prior to storage (followed by a second measurement before the motor is placed in service). Another baseline measurement, the polarization index of the form coil windings prior to storage (annually, if motor is in storage for several years) also is suggested.
   7. Carbon brushes in some electric motors may experience problems with chemical reaction during storage unless you do the following. Lift the brushes from the commutator and/or slip rings. You should also place the bushes in a relaxed position if possible to prevent against the springs from getting weak.

   Use these long-term storage suggestions on your electric motors and you won’t need worry if it works when the time comes to place it in service. Learn more about electric motor maintenance with our free eBook, Preventative vs. Predictive Motor Maintenance.

   You can also contact a Renown representative today