Archives for 2019

Motor Magnetic Center

Running a motor uncoupled will pull the motor rotor into a magnetic center, often marked on the shaft to ensure that the rotor is lined up on the magnetic center when it is coupled to the load. Axial misalignment of a coupling can occur if the coupling ends are not close enough when they are bolted together resulting in pulling the rotor out of magnetic center. When this happens the rotor is constantly trying to pull itself through axial thrusting back to magnetic center and could result in uneven and or excessive bearing wear. Using the EMAX technology you can evaluate the 5th harmonic peak as an indicator of this magnetic center offset and axial movement. Normally the 5th harmonic is a single clean peak in the current spectrum. However, if axial thrusting is occurring the 5th harmonic will split into two smeared peaks.

To see an example and hear a case study on a suspect magnetic center offset visit the PdMA YouTube Channel at https://www.youtube.com/watch?v=Mh2Cx6yqviw

Don’t Start that Motor!

Back in May of this year we discussed the importance of Quality Control testing of your new or refurbished electric motors. Today we have a case study showing the importance of Quality Control testing for a newly commissioned system. All too often a new or refurbished motor gets installed and started on looks alone with no pre-qualifying data to justify the asset’s health. Where was the motor stored? How was the motor shipped? Were the power leads (Power Circuit) connected properly? Is the voltage supply balanced? Is the motor properly engineered and specified for the application? These are just a few questions that a good Quality Control program and testing plan will be able to answer. For MCEMAX® users, a three minute test will give qualifying baseline information about the motor to compare to industry standards and support an acceptance decision. And remember, for any newly installed motor, don’t start the motor unless the electric motor reliability team is on site to perform In-Rush/Start-Up testing on the motor when it first starts. This start-up data is crucial in qualifying the power quality, power circuit, stator, rotor and air gap. Additionally, it gives you critical comparison data for future troubleshooting efforts involving this motor and its application.

To see a new case study on the results of missing a quality control test, view the PdMA YouTube channel at:

https://www.youtube.com/watch?v=2Wp2nwOwxeY

Converting motors from horizontal mount to vertical mount

Examine mechanical factors that should be considered when applying a horizontal ball-bearing motor in a vertical mounting position.

By Tom Bishop, P.E., EASA

Oct 08, 2019

Occasionally an end user wants to take a motor designed for horizontal mounting and use it in a vertical position. (Figure 1 illustrates a horizontal motor in a vertical shaft down position.) This article addresses some of the key mechanical factors that should be considered when applying a horizontal ball-bearing motor in a vertical mounting position.

These key factors include:

Axial thrust load capacity of bearing supporting rotor weight
Rotor weight
Weight of output shaft attachments
Axial thrust from direct-connected driven equipment\
Bearing lubrication paths
Bearing lubricant retention
Shaft up or shaft down orientation
Ingress protection
Locking axial thrust bearing

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Customer Discontinuing Coal to Steam Operations

Decatur Industrial Works on Environmentally Friendly Retrofit & Upgrade

In an effort to go green, our customer’s facility is shutting down coal to steam operations. They have an MR compressor application that is driven by a steam turbine. The process engineering team requested our assistance with motor application expertise and guidance in retrofitting to an electric motor driven solution for the existing compressor.

D.I.E collaborated with the customer’s engineering team on a motor and mounting adapter base solution to the existing compressor frame. This solution needed to reliably function in a somewhat challenging environment. We strategized in a team effort arriving at an adapter base and motor design that provided the required torque within the challenging thermal and dimensional limits available. We determined that this application would require a 1500hp motor torque requirements with a very specialized adapter base. The adapter base and motor will be built by the Siemens Above-NEMA (ANEMA) motor plant in Norwood, OH. (story continues below picture.)

This upgrade will maximize their process efficiencies. Steam turbines are less efficient, compared to electric drive systems. This is especially true when heat losses from steam are considered. Steam turbines also require more planned shutdowns, and due to their significant number of moving parts, are comparatively less reliable than electric motor drive systems. These advantages combine to maximize the customer’s equipment uptime and productivity.

Decatur Industrial would love to help your facility see what productivity gains you can achieve through similar upgrades. Thanks to their efficiency, reliability, and attractive price points, electric motor variable speed drive systems are an attractive option.