Larry Payne
Heights Armature Works, Inc.

Most of us have had to battle with the occasional two-pole vertical motor and survived. The following case study is a story not only of survival, but of success. The background A few years ago, our service center had a customer with six, two-pole 4000 VAC 900 hp solid-shaft vertical motors; there were four installed and two spares. They were direct on-line start atomizer motors driving gearboxes in a coalfied power plant and were installed in the bottom of inverted conical structures supported from the roof of the building. The installation suffered from high ambient temperatures and a very marginal support structure for a vertical machine. Before coming to us, the customer had battled with the motor installation problems for years. The original motors, plagued with high vibration and frequent bearing failures, were replaced with another manufacturer's design. Unfortunately, that was no help. Several service centers had rebuilt these motors, but none of them had complete information regarding the installation and the high failure rate. Even motors returned to the OEM repair centers were extremely unreliable. The shortest run time was twenty minutes for one motor repaired by the OEM. The longest run time was less than two months. Cost had become virtually a moot point for the customer. The customer correctly decided to send all motors to one service center and communicate everything that was known about the problems associated with these motors. We were selected, possibly because of our close proximity to the plant.

Other topics discussed are:

• Grease and bearings
• Bearing problems
• Disassembly and in-process
• Assembly and test run
• Keys to success

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