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Tag Archive: motor drive maintenance

  1. What’s that Noise My Motor Bearing is Making?

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    In the course of our work, our team at Renown Electric Motors & Repair Inc. comes across a lot of motor drive and motor bearing issues.

    Noise coming from the motor drive or bearing is a particularly common complaint. Working with our partner NTN Corporation, a Japanese bearing manufacturer with global reach, we compiled a few common causes of noise and vibrations in bearings and drives — and how to fix them.

    What noise is my motor bearing making?

    Cylindrical Roller Bearing

    A motor bearing may make any number of noises, not all of which are indicative of a serious issue. Tinkling or rustling sounds, for example, are generally caused by dust or dirt and can be resolved with a decent cleaning. Others, however, can be more problematic.

    Buzz or Roar

    If your bearing is making a vibratory sound ranging from a light buzz to a considerable roar that increases in volume and pitch as speed changes, this is problematic.

    Spherical Roller Bearing

    This issue can be caused by any one of a number of factors, including resonation, a poorly shaped shaft, deformed bearing, brinelling, or vibrating parts. Note that in very large bearings, a minor buzzing is normal.

    Screech or Howl

    A screeching or howling sound, particularly on cylindrical roller bearings, that changes with speed is an indication of radial clearance that is too large.
    (Note that if the sound is metallic and fades temporarily after being greased, the lubrication you are using is of a poor quality.)

    Crunch

    A crunching sound, especially one that can be felt when the bearing is moved by hand, could be caused by a deformed bearing or bad dust contamination. More seriously, it could mean that balls, rollers, or raceway surfaces are being scored.

    Chatter

    A chatter that is audible not only at high speeds but at low ones as well can mean that the rollers on a full-roller bearing are bumping into each other.

    Find more causes of noise and vibration in NTN’s Motor Bearing Care & Maintenance Guide.

     

    Why is my motor vibrating?Motor Bearing Maintenance Guide

    What do each of these sounds have in common? They can be traced back to vibrations in the motor. The degree of the damage caused by these sounds’ sources depends on both the amplitude and frequency of the vibrations causing them.

    Slight motor vibration is normal. The presence of a variable frequency drive (VFD), while helpful for decreasing energy use, introduces electrical noise in the form of Common Mode Current. Common Mode Current can increase vibrations to dangerous levels that can cause audible noise issues and, more worryingly, badly damage your motor bearings.

    The Ultimate Solution

    CoolBLUE inductive absorbers, also called common mode chokes, are inductors that have been specially designed to reduce common mode current — they absorb the electrical noise, thus “choking” the current.

    Proper installation of CoolBLUE inductive absorbers and NaLA differential mode line absorbers, both manufactured by Renown partner MH&W International, can decrease VFD-caused Common Mode Current drastically, as much as 70% or more. By reducing this noise and the vibration it causes, you will maximize the longevity and reliability of your equipment while minimizing maintenance cost and unscheduled downtime.

    Learn more about Renown’s CoolBLUE Inductive Absorbers or see how they work in our motor bearing current case study.

  2. Motor Repair Projects: See How Renown’s Process Works

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    Renown Electric treats every motor project — big or small — with the same level of care to produce the best quality results for our customers.

    To illustrate how we handle motor repair projects smoothly from start to finish, we’ve compiled details from some of our past jobs into a new case studies page on our website. Here are a few highlights:

    Motor Repair

    Motorrepair

    In one recent case, a silicon rubber mill was experiencing brake issues as the result of an outdated control panel. The owner of the mill, which no longer met the required safety standards, approached Renown for motor drive maintenance assistance to help create a safer work environment. Renown collaborated with Mann Electric and a top motor and machine control support company, Benshaw Advanced Controls and Drives, to examine the controls.

    Collaboratively, we determined that the best solution would be to completely replace the control panel, while accommodating the old wound rotor motor. We reestablished workplace safety at the mill by providing a new motor control panel with advanced synchronous control capabilities, a soft start and emergency stop functionality to meet current workplace health and safety standards.

    Industrial Motors

    In an AC and DC motor case study, Renown conducted a motor bearing current test with our CoolBLUE inductive absorbers and NaLA noise line absorbers to find a solution to harmful voltage spikes, which had been causing fluting and lubrication breakdown. We found that these absorbers, also known as common mode chokes, reduced bearing damage by eliminating these high frequency currents and keeping voltage within safe limits.

    Two Male Technician Machinist Worker At Work Adjusting Elevator Mechanism Of Lift With Spanner

    Elevator Motors

    In another motor bearing current test — in this case, for elevator motor drives — Renown found that the common mode chokes reduced harmful electrical “noise” by up to 60% in DC motors and 65% in AC motors. This eliminated harmful currents to the armature and bearings and in the long run will reduce maintenance and prolong the life of the motor.

    Renown Can Help

    For more examples of recent projects and to learn how Renown can help you to prevent motor problems across a variety of applications, please visit our case studies page.

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