Here You Go.

Everyone who deals with vendors has a choice to make. Should you beat them up and show them "who's boss" or should you partner with them in the spirit of cooperation? Which one do you choose? Can you do both?

There are a lot of articles on managing vendor relationships, many people much smarter than i am write articles and books on this topic. However, there is a fundamental, philosophical choice that i see companies (and individuals alone) make when dealing with vendors. Are they open and honest and treat their vendors as partners in advancing items at their location? Or do they constantly demand more and more of the vendor and want to pay less?

Todd A. Hatfield - Vice President of Engineering & Repair, HECO

This is an electric motor repair case study on a 800HP, 900RPM, 4000V Coal Crusher Motor for a Midwest-US based coal fired power generation plant. In 2006 the utility came to HECO after years of repetitive failures circling around the electric motor's rotor. This was originally presented at the Reliability, Process, and Maintenance (RPM) Symposium on Sep 13-14, 2016.

Before reading about these different tests, please check out our last few articled on electric motor theory and rotor bar cracks:

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 motor accelerates. The longer the starting period, the more cyclic forces the rotor cage must endure.

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.