Request Expert

Expert has broad and deep capability in motors and generators. He knows the design process from the centerline out. He has designed machines with special design constraints. He knows the theories of operation and control, and can specify a machine for an application. He knows not just electromagnetic design but mechanical and thermal design of machines. He has detailed knowledge of special materials used in electric machines, including permanent magnets, electrical insulation, and electrical steel. He also has knowledge of the effects of power electronics drives on electric machines. He has experience with failure analysis of machines ranging from fractional horsepower to hundreds of megawatts in rating.

Expert has experience in both the design and the application of power electronics converters and drives.

He understands the principles of operation and considerations of control. He is knowledgeable in design for heat transfer and limitations on size and weight of such devices. He has knowledge of life-limiting processes and design for long life.

Expert has detailed knowledge of the design and operation of the electrical power generation and distribution system in a conventional automobile. He has detailed knowledge of both the design and operation of automotive alternators and has contributed to innovations in this technology. Similarly, he has substantial knowledge of the design and construction of all of the electrical power loads in a typical automobile. He knows about wire harnesses, connectors, and fuses. He understands the multiple functions of the battery, and knows the life-limiting processes of this device.

Expert has extensive knowledge of the design and operation of hybrid electric vehicles. He understands the trade-offs involved in coordinating the operation of an internal combustion engine and an electrical drive system. He has the ability to design and/or specify the electrical components of such systems. He understands the operation of internal combustion engines and how the system can be and is used to enhance the fuel efficiency of the vehicle. He is aware of the design trade-offs between performance, mass, and cost.

Expert is familiar with the design and construction of all the principle components of modern electric drive systems for the application of mechanical power, in both industrial and transportation applications. He understands how the components of the system work together to achieve the intended function and how they affect one another. He has experience designing electric drive systems for unusual specifications.

Expert is knowledgeable about the hazards to human health and safety from exposure to electric current. He knows the existing literature concerning the response of the body to contact with electrical conductors, and understands the principles commonly applied to prevent adverse results. Further, he understands the ways in which electrical power systems can originate fires, and the means used to mitigate or prevent this result. He knows the hazards of exposure to arc flash.

Expert has successfully completed failure analysis on a range of electrical devices. He applies his knowledge of the intended operation of the device, along with the evidence presented by the failed device or devices. Background knowledge, including insulation life and failure, arc formation and extinction, arc physics, heat generation and heat transfer, mechanical stress and fatigue, and other physical processes, is applied as appropriate.

Expert has a practical working knowledge of electrical arcs. He understands the conditions which lead to arc formation, the requirements for an arc to be maintained, and the conditions for arc extinguishment. He is able to examine apparatus in which arcing has occurred and draw conclusions about the process by which the arc arose.

This expert has practical experience evaluating evidence in cases of fires suspected of being of electric origin. He has seen both cases in which the fire was conclusively of electrical origin and cases in which other experts have concluded that a fire is of electric origin, even though the evidence is equally supportive of other theories. Background knowledge in electrical insulation, electrical contact resistance, the formation and extinction of electrical arcs and heat transfer are useful skills in these matters.

Expert has a detailed knowledge of the application of permanent magnets to practical devices. He understands the operation of permanent magnets with regard to their magnetic properties and also with regard to their mechanical properties and the influence of temperature on performance. He knows the issues associated with magnetization and demagnetization, and has practical experience in measuring the extent of magnetization and in the safe handling of large magnetized high-strength magnets and structures containing magnetized magnets.

Expert has experience with cases of malfunctioning electrical switchgear. The relevant skills he possesses include knowledge of the proper operation of switchgear, knowledge of arc creation and extinction, design of dielectric systems, and design and analysis of mechanical and electromagnetic actuation mechanisms.

Expert has experience evaluating the operation of electrical circuits in consumer appliances and other devices. He understands circuit theory and the design process for the proper installation and use of many common circuit elements. He is capable of evaluating operation under normal and abnormal circumstances.

Expert has firsthand experience in the design and construction of systems of electromechanical components (including design of the components themselves) to accomplish unusual or unique functions. He has the skill and ability to create and evaluate systems to perform their intended function under a range of environmental conditions.

Expert has experience in the design of superconducting electromagnets for a range of uses. He has designed electric generators and motors with superconducting field windings, and superconducting electromagnets for use in medical MRI imaging systems. He has evaluated superconducting magnets as elements in energy storage systems and for use in magnetic levitation.

Expert knows the principles of magnetic levitation and magnetic bearings. He has evaluated in detail the design of magnetic bearing systems, and has the ability to evaluate the dynamic response of complicated rotating mechanical systems using magnetic bearings.

Expert has substantial direct experience with dynamic balancing of rotating machinery. He has performed balancing in multiple planes. He has successfully balanced flexible rotors for operation through a rotor-bending critical speed. He understands the function and operation of commercial rotor balancing equipment, but can also work with custom or even improvised measuring equipment.

Expert has a big-picture understanding of electrical insulation. He understands the basic function of electrical insulation, and is familiar with the known processes of electrical insulation aging and degradation. He understands electrical insulation failure. He is familiar with practical considerations in insulation system design, including surface creepage and partial discharge tolerance and prevention.

Expert is very familiar with the design and construction of large central station electric power generators. He understands the principles of operation and is familiar with most common (and some uncommon) failure modes. He has performed root cause failure analysis on a unit rated at hundreds of Megawatts. He also has great familiarity with the design and construction of automotive alternators. He has made custom modifications to such machines.

Expert has detailed knowledge of carbon brushes as elements of electrical systems. He understands the theory of commutation and the design of systems to accomplish this function. He knows the properties of various grades of carbon and their advantages and disadvantages. He knows the design and construction of brush holders and has offered expert opinion on the subject.

Failed Pump Motor:
An induction motor driving a centrifugal pump in a dormitory domestic water system had suffered a ground-fault failure, creating an electrical shock hazard for the users of the system. Expert was provided with the failed motor, attached to the pump and some associated controls.
An examination of the windings of the motor showed extensive darkening of the insulation of the motor start winding. By electrical test, the start winding was observed to be shorted to the motor frame. The conductor was embrittled. From these observations, Expert concluded that the overheating had occurred over a substantial time, and had in all probability caused the insulation failure.
The motor was controlled by a pressure switch, which was also included in the specimen provided to Expert. The pressure switch was connected directly to the output of the pump, without an intervening check valve.
In this configuration, so long as the building demand for water approximated the output of the pump, the pump would run and supply water to the building. However, in times of moderate or low water usage, the pump would build the pressure in the system to a level which caused the pressure switch to turn off the motor.
In the absence of the check valve, water would then immediately flow backward through the pump, causing the system pressure to quickly fall to the point where the pressure control low limit would be reached. The pressure switch would then immediately restart the motor.
This process of continuously shutting down and restarting the motor subjected the start winding of the motor to a duty far beyond any reasonable limit, and with virtual certainty caused the observed overheating of the start winding.
The age of the system at failure was consistent with the system having been originally installed in the flawed configuration observed by Expert.
Expert was also able to note that if the system had been wired in accordance with normal modern wiring practice, the insulation failure would have resulted in a tripped circuit breaker, rather than an ongoing electrical shock hazard.
Aided at least in part by these findings, the client was able to reach a settlement without the expense of a trial.Failed Stator Winding in Large Turbogenerator:
A nearly new steam turbine generator was scheduled for a shutdown, in part to do some planned maintenance. A few hours before the scheduled shutdown, the power plant was tripped off line by the action of automatic circuit breakers following a nearby phase to ground short on the transmission line.
When the generator was opened for the planned maintenance, re-solidified melted copper was discovered in the bottom of the unit. Further inspection revealed that the stator winding had three separate open circuits, each resulting from the complete melt-through of a stator bar in the connector-end end windings. This machine had multiple parallel circuits in each stator phase, and there was only one parallel circuit open in each phase, so balanced operation remained possible.
Expert was engaged to perform a root cause analysis.
The generator was examined in place. Expert recommended that the end winding structure be removed in major sections and preserved for further study. This allowed further investigation to take place even as the stator was rewound for return to service.
Expert concluded that the cause of the failures was high cycle fatigue failure, due to inadequate support of the stator end winding. Subsequent examination of the preserved end winding found a number of places where other conductor strands had fractured in locations similar to the locations of the open circuits. These failed strands are reasonably compelling evidence that more failures would have occurred had the generator not been taken out of service.
Expert’s conclusion was not accepted by the manufacturer of the generator -- but that manufacturer, who was also performing the field rewind, did agree to install a substantially different end winding lacing and blocking system as part of the rewind process.
By applying engineering analysis, Expert was able to show that the manufacturer’s alternative theory of the failure was fundamentally inconsistent with the physical evidence of the failed parts.
Based at least in part on Expert’s findings, the client was able to negotiate a satisfactory sharing of financial responsibility with the manufacturer.Trade Secret:
A key employee left a manufacturing company, and went to work for another company, which was in the process of designing a family of products to compete with the first company. The first company accused the second company of theft of trade secrets, and sued. Expert, hired by attorneys for the second company, felt that the concepts which were identified by the first party as trade secrets were widely known to electrical engineers. He was able to support this opinion with corroborative examples, including a journal article from the 19th century. The case went to trial, and the judge ruled in favor of the client.