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Q Q:3136378118
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斷開時(shí)間足夠短,以防止短路電流達(dá)到其本來可以達(dá)到的峰值”(IEC 60947-2,定義2.3)。
實(shí)際上,ABB SACE塑殼斷路器SACE Tmax XT和Tmax T
在短路條件下,串聯(lián)極為迅速(跳閘時(shí)間為
大約幾毫秒),因此不可能使用時(shí)間電流
協(xié)調(diào)研究曲線。
這些現(xiàn)象主要是動(dòng)態(tài)的(因此與平方成正比)
,并且可以使用特定的
讓我們通過能量曲線。
通常,有必要驗(yàn)證斷路器下游的通電能量是否低于完成斷路器連接所需的能量值
打開上游斷路器。
這種歧視肯定比以前更難考慮
因?yàn)樗诤艽蟪潭壬先Q于兩個(gè)設(shè)備之間的交互
按系列放置,要求訪問數(shù)據(jù),但終往往無法訪問
使用者制造商提供表格、規(guī)則和計(jì)算程序,其中
給出了不同組合之間的小鑒別極限
斷路器。
優(yōu)勢(shì):
•快速斷開,跳閘時(shí)間隨著短路電流而減少
增加;
•減少故障造成的損壞(熱應(yīng)力和動(dòng)態(tài)應(yīng)力),
對(duì)供電系統(tǒng)的干擾,成本。。。;
•歧視水平不再受短期價(jià)值的限制
耐受電流I
裝置能夠承受的cw;
•大量歧視級(jí)別;
•協(xié)調(diào)不同限流裝置(保險(xiǎn)絲、斷路器等)的可能性即使它們位于沿
鏈條



break time short enough to prevent the short-circuit current reaching its otherwise attainable peak value” (IEC 60947-2, def. 2.3). In practice, ABB SACE moulded-case circuit-breakers SACE Tmax XT and Tmax T series, under short-circuit conditions, are extremely rapid (tripping times of about some milliseconds) and therefore it is impossible to use the time-current curves for the coordination studies. The phenomena are mainly dynamic (and therefore proportional to the square of the instantaneous current value) and can be described by using the specific let-through energy curves. In general, it is necessary to verify that the let-through energy of the circuitbreaker downstream is lower than the energy value needed to complete the opening of the circuit-breaker upstream. This type of discrimination is certainly more difficult to consider than the previous ones because it depends largely on the interaction between the two devices placed in series and demands access to data often unavailable to the end user. Manufacturers provide tables, rules and calculation programs in which the minimum discrimination limits are given between different combinations of circuit- breakers. Advantages: • fast breaking, with tripping times which reduce as the short-circuit current increases; • reduction of the damages caused by the fault (thermal and dynamic stresses), of the disturbances to the power supply system, of the costs...; • the discrimination level is no longer limited by the value of the short-time withstand current I cw which the devices can withstand; • large number of discrimination levels; • possibility of coordination of different current-limiting devices (fuses, circuitbreakers,..) even if they are positioned in intermediate positions along the chain
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