Performance of synchronous motors loss-of-synchronism protection
Synchronous motors are rarely designed to operate asynchronously for extended periods of time. When a synchronous motor experiences a mechanical load exceeding its pull out torque, it enters asynchronous operation, under which the interaction between the stator and rotor magnetic fields causes damaging mechanical stress and vibrations. Also, induced currents in the rotor cause extra heating that quickly damages the rotor windings. Asynchronous operation must be detected and dealt with by allowing time for resynchronization or by tripping the motor to avoid thermal overload and damage. Two protection elements are often used to detect asynchronous motor operation: the power factor element and the out-of-step element. This paper compares the performance of the two elements to protect a 20 MW synchronous motor subjected to pull out conditions.
Loss-of-Field Protection for Synchronous Machines [includes discussion]
THE COMPLETE or partial loss of the d-c supply to a large synchronous machine can have serious consequences. This may be loss of stability in the power system with the resulting major loss of service or costly damage to the machine itself. On the other hand, it is desirable to maintain the machine on the line as long as possible supplying kilowatts to the system.
Iustitia Dei: A History of the Christian Doctrine of Justification
Preface Acknowledgements 1. Prolegomena 2. The fountainhead: Augustine of Hippo 3. The development of the doctrine in the medieval period 4. The medieval schools of thought on justification 5. The transition from the medieval to the modern period 6. The development of the doctrine in the Reformation period 7. The Tridentine decree of justification 8. The legacy of the English Reformation 9. The modern period Appendix: a glossary of medieval soteriological terms Abbreviations Notes Bibliography Index.