英语翻译III.NEW CIRCUIT BREAKER TECHNOLOGIESThe concept of a sol

英语翻译
III.NEW CIRCUIT BREAKER TECHNOLOGIES
The concept of a solid state circuit breaker is not new.Numerous attempts have been made at implementing power semiconductor-based breakers,but few have made a significant positive impact on power systems.A fundamental
problem with most prior concepts is the desire to have the solid state breaker behave like a traditional electromechanical breaker in terms of fault let-through current and coordination.High let-through current enables traditional coordination with downstream breakers or fuses,but it does not complement the capability of modern power semiconductors.AC breakers
have been constructed using SCRs connected in inverse parallel as shown in Fig.7.While offering silent operation and long life,these breakers still have ½ line cycle type response,do not current limit,and are not suitable for DC systems.Hence they provide minimal performance improvements to the overall power distribution system.For worst case asymmetrical fault currents (i.e.200kA peak for 85kArms available current) fuses must be employed to protect the SCRs.
Thermal losses are significant due to the minimum SCR onstate voltage drop.A hybrid breaker (contact across the SCRs) can eliminate the conduction loss and need for an arcing contact structure (i.e.virtual arcless switching),but provides minimal system performance advantages.
Fig.7.SCR based AC circuit breaker A superior solution is one in which breakers are current limiting by responding early and quickly to an increasing fault current.Current liming in a traditional system can present
problems with fault coordination.Simply adding a few current limiting breakers to a conventional system may be problematic.The entire system must be designed with current limiting breakers as key driver of the protection requirements.The Navy,with its “closed” shipboard power system,is in a
unique position to be able to take advantage of new technologies by defining a power system that takes advantage of new breaker technologies.
wua~一楼二楼的不行啊~要手译!

III.NEW CIRCUIT BREAKER TECHNOLOGIES
新型断路器技术
The concept of a solid state circuit breaker is not new.Numerous attempts have been made at implementing power semiconductor-based breakers,but few have made a significant positive impact on power systems.A fundamental problem with most prior concepts is the desire to have the solid state breaker behave like a traditional electromechanical breaker in terms of fault let-through current and coordination.High let-through current enables traditional coordination with downstream breakers or fuses,but it does not complement the capability of modern power semiconductors.AC breakers
have been constructed using SCRs connected in inverse parallel as shown in Fig.7.While offering silent operation and long life,these breakers still have ½ line cycle type response,do not current limit,and are not suitable for DC systems.Hence they provide minimal performance improvements to the overall power distribution system.For worst case asymmetrical fault currents (i.e.200kA peak for 85kArms available current) fuses must be employed to protect the SCRs.
固态断路器这一概念并不陌生.人们做了很多努力试图创造出以功率半导体为基础的断路器,但是在功率系统方面有重大成效的成功者却寥寥无几.大部分之前的概念的基本问题在于,在通过漏电电流及配位方面,人们总希望固态断路器能像传统的机电断路器那样工作.通过的高强度漏电电流可使传统的下游配位短路或烧断,但其无法完善现代的功率半导体.人们已经制作出使用SCR可控硅的交流断路器,该可控硅由两个单向可控硅反并联而成,如图7所示.在进行静音和长使用期限操作时,这些断路器有半线循环类型反应,无电流上限,且不适合DC 系统.因此它们对整体配电系统的操作改善方面的作用很小.在最坏情况中,若存在不均衡漏电电流（如 200kA 峰值电流相对于 85kArms 的可用电流）,必须使用保险丝以保护可控硅.
Thermal losses are significant due to the minimum SCR onstate voltage drop.A hybrid breaker (contact across the SCRs) can eliminate the conduction loss and need for an arcing contact structure (i.e.virtual arcless switching),but provides minimal system performance advantages.
因为最小可控硅的导通电压降的缘故,热损耗显得至关重要.混合式断路器（在可控硅处交叉连接）可消除传导损耗,也不需要弧击穿连接构造（如虚拟无弧通断）,但可提供最小系统操作优势.
Fig.7.SCR based AC circuit breaker
A superior solution is one in which breakers are current limiting by responding early and quickly to an increasing fault current.Current liming in a traditional system can present problems with fault coordination.Simply adding a few current limiting breakers to a conventional system may be problematic.The entire system must be designed with current limiting breakers as key driver of the protection requirements.The Navy,with its “closed” shipboard power system,is in a unique position to be able to take advantage of new technologies by defining a power system that takes advantage of new breaker technologies.
图7所示,以可控硅为基础的交流断路器.
一个较好的解决方法是,断路器在进行电流限制时,对上升的漏电电流做出较早的迅速的反应.在传统系统中电流加石灰会引出漏电配位的问题.仅仅只是在一个常规系统上加入一些电流限制断路器的做法也会产生问题.设计整个系统时必须以电流限制断路器作为保护要求的主要驱动力.对于定义一个利用新型断路器技术的电力系统,海军舰船及其“封闭式的”舰船电力系统享有独一无二的优势以采用此项新型技术.