電力系統中英文外文文獻翻譯(完整版)

　　

【正文】 o month, 6 points at which additional capacity of equipment is required may be recognized and provision made for the installation of additional equipment. Thus instrumentation serves as a guide for future construction in a growing power system. Occasionally, under emergency conditions, a system operator observes that his system load exceeds the ability of the available generating and transmission equipment. He is then faced with the problem of load shedding or ,more properly, load conservation. It is then necessary to drop selected loads where service interruption is least objectionable. In such an event, he relies on the many instruments which provide information relative to systemoperation conditions. Instruments may sound alarms as advance warnings of conditions requiring action to avoid damage to equipment operating beyond its design limitation. In the event of extreme conditions such as powersystem faults, defective equipment is switched out of service automatically. Instruments that continuously monitor current voltage, and other quantities must be able to identify the faulted equipment and to bring about operation of the circuit breakers which remove it from service, while leaving in service all other equipment on the operating system. The many different electrical devices on a power system and those owned by the customers are designed for operation within certain specified ranges. Operation, excessive deterioration, or (in extreme cases ) the destruction of the device. Careful attention to the conditions under which equipment is operating may indicate corrective action that must be taken. Overcurrent on all electrical devices is undesirable, as it produces excessive temperatures, inefficient operation, and reduced service life. Overcurrent in residential circuits may bring about disconnection of the circuit by fuse or breaker action. Overcurrent in motors may damage insulation, with possible early insulation failure. Undervoltage considerably reduces the efficiency of incandescent lamps and may result in nonoperation of fluorescent lamps. Undervoltage of the power supply to motors may result in excessive currents in the motors, with possible damage to windings. Overvoltage increases the light output of lamps but in many instances seriously shortens useful life. Overvoltage applied to motors and transformers may result in excessive losses within the iron, with possible damage to the iron or to the adjacent winding insulation. Overspeed of rotating machines may result in structural damage to rotating parts. The overspeed of the customers’ production equipment may result in an inferior quality of the product. An outofstep condition existing between two generators or between a generator and a synchronous motor results in an interruption of useful power transfer between the two machines. An outofstep condition should be recognized promptly and the machines separated from each other. They may then be resynchronized and brought back into service. Instruments of many different types must be installed at many locations on a power system and on the premises of the many customers. With such instruments, conditions existing on the system may be continuously monitored. 。 2. water。 機器的超速旋轉有可能對機器的轉動部件造成結構上的損壞。仔細觀察設備的運行情況就可以發現需要