November 21, 2016
Tom Spettel, Senior Reliability Engineer, Category IV ISO Certified Vibration Analyst The below video is a case study of a 400HP, 3600RPM (2 Pole) Boiler Feed Water Pump Motor that had vibration problems after a used motor was put in place of the original motor. This was originally presented at the 2016 Reliability, Process, & …
November 14, 2016
Todd A. Hatfield – Vice President of Engineering & Repair, HECO This is the first article (video) in a series of articles on The Basics of AC Induction Motors. This video explores the basic principles of AC Induction motors. This segment discusses magnetism basics, the law of electromagnetic induction, AC current, and the explanation of …
November 9, 2016
Tom Spettel, Senior Reliability Engineer, Category IV ISO Certified Vibration Analyst The below video is a case study of a 4000HP Induced Draft (I.D.) Fan Structural Resonance. This was originally presented at the 2016 Reliability, Process, & Maintenance Symposium (RPM) in Kalamazoo, Michigan on September 13-14, 2016.
November 1, 2016
Part 1 – On-Site Findings Part 2 – In-Shop Findings Part 3 – Repairs Taken & Results The results of the “on-site” findings in conjunction with the “in-shop” inspection led to the electric motor repair approval to build a new rotor assembly for this Boiler Feed Pump Motor (9000HP, 1800RPM, 13,200v, Siemens Allis). This is …
October 24, 2016
Part 1 – On-Site Findings Part 2 – In-Shop Findings Part 3 – Repairs Taken & Results The results of the “on-site” findings resulted in the determination to pull this Boiler Feed Pump Motor (9000HP, 1800RPM, 13,200v, Siemens Allis) out for repair. The motor was removed and was received by the HECO motor repair shop …
October 8, 2016
Part 1 – On-Site Findings Part 2 – In-Shop Findings Part 3 – Repairs Taken & Results On March 09, 2015, HECO was called in to help evaluate vibration and noise concerns with a coal-fired power generation plant’s Boiler Feed Pump Motor. (9000HP, 1800RPM, 13,200v, Siemens Allis). Initial information from the plant vibration team indicated …
August 11, 2016
Before reading about these different tests, please check out our last few articled on electric motor theory and rotor bar cracks: How Does an Induction Electric Motor’s Rotor Work? How do 2-pole Electric Motor Rotor Bars Crack? Besides a simple visual inspection, below is a summary of the most common methods of detecting cracked rotor …
August 4, 2016
Rotor bars of 2-pole (3600RPM) rotors are subjected to high stresses caused by repeated starting, thermal expansion and centrifugal forces. The repeated starting with resultant cyclic forces causes the bars to loosen. This is because the rotating magnetic stator field applies rapidly alternating forces to each rotor bar, diminishing in intensity and frequency as the …
July 28, 2016
The induction of current flow through an induction electric motor’s rotors bars occurs when current is applied to the stator. This applied current through the stator windings starts the rotation of the stators magnetic field at line frequency. The rotor bars of the stationary rotor are then subjected to the maximum relative motion of the …
July 19, 2016
Shaft circulating currents are caused from “dissymmetries” in the magnetic paths through the stator and rotor iron. As the rotor rotates within the stator and as the stators magnetic field rotates, small differences in the magnetic “reluctance” of the core parts generate small voltages between the ends of the shaft. As you can see from …
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