This book was developed to help electric motor technicians and engineers prevent repeated failures because the root cause of failure was never determined. By using a proven methodology combined with extensive lists of known causes of failures, one can identify the actual cause of failure without being an “industry expert.” In fact, when properly used, this material will polish one’s diagnostic skills that would qualify one as an industry expert.

I suspect that just about everyone in our industry at one time or another has had the joy of repairing a “purpose-built” motor. This kind of motor is built for a specific purpose and has characteristics that may allow it to operate under non-standard conditions. Due to the limited information that some of them display on the nameplate, the repair of these motors can be somewhat of a challenge. Sometimes these motors possess differences such as the color of paint, the shaft size, the bearing size, or type. It can be the operating temperature and at times it can be the motor in its entirety. Following are a few useful tips we use when repairing a motor with so many question marks.

Sospecho que casi todos en nuestra industria alguna vez han tenido el placer de reparar un motor “fabricado con requisitos especiales”. Este tipo de motor está construido para un propósito específico y tiene características que le pueden permitir funcionar bajo condiciones no habituales. Debido a la información limitada que algunos de ellos muestran en su placa de datos, la reparación de estos motores puede resultar un reto.

This article demonstrates the suitability of resin rich insulation systems for hydro generator service and highlights the advantages of being able to introduce remedial measures during the life of the winding to address issues and ensure that acceptable winding life is achieved 

This article describes the technical issues in online partial discharge (PD) detection on motors fed by VS-PWM drives, and gives an example of one system that detected the PD successfully.

By this time we should all know that stator core loss testing is a required part of a quality rewind. A core loss test before and after burn-off is specified in the EASA Recommended Practice for the Repair of Rotating Electrical Apparatus (ANSI/EASA AR100) and The Effect of Repair/Rewinding on Motor Efficiency; EASA/AEMT Rewind Study and Good Practice Guide to Maintain Motor Efficiency.

Topics covered in this article include:

• Lessons learned
• Rebates add incentive
• Learning from other members
• Determining if the core is usable
• Accurate iron measurements

This presentation covers:

• Brief overview of disassembly and evidence of failure
• Discussion of possible failure scenarios
• Review of actual repairs, modification and reassembly
• Update of machine's present operation

The repair of the various types of pumps represents an important segment of the service center repair market. Electric motors and pumps are the two most widely used industrial machine components.                                                                                                                                                                                                                       

Although there are two principle pump types (dynamic and positive displacement), this manual focuses on dynamic pumps and the fundamentals of dynamic pump repair. The information it contains will be helpful to both novice and experienced pump repair technicians, to supervisors and managers of pump repair operations, and to customer service and sales personnel who communicate with customers about pump repair issues.

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 mo-tors; 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