產(chǎn)品細節(jié)介紹
3BHE022293R0101控制處理器模塊
a） 369 CT耐受性當相位或接地CT能夠驅(qū)動大量電流進入繼電器中的插入式CT時，耐受性非常重要。當電流互感器的尺寸不足以承受繼電器的負荷時，這通常發(fā)生在改造裝置上。
電子繼電器通常具有低負載（8m? 369），而較舊的機電繼電器通常具有較高的負擔(dān)（1?).
對于大電流接地故障，系統(tǒng)將為低電阻或可靠接地。決定可在這些類型系統(tǒng)中流動的接地故障電流的限制因素是電源容量。耐受性對于高電阻接地系統(tǒng)的接地故障。在這些系統(tǒng)中，電阻器將電源連接至電源（發(fā)電機、變壓器）接地。選擇電阻值，以便在發(fā)生接地故障時，電流流量限制在低值，通常為5、10或20 a。由于存在較大故障的可能性（排除高電阻接地系統(tǒng)上的接地故障），故障必須盡快清除。因此，建議短路和高接地故障的延時為設(shè)置為瞬時。那么369 CT承受高耐受的持續(xù)時間將小于250 ms（369反應(yīng)時間小于50ms+斷路器清除時間）。必須注意確保中斷裝置能夠中斷潛在故障。如果不，應(yīng)使用其他中斷故障的方法，并且應(yīng)禁用相關(guān)功能（例如，熔斷接觸器依靠保險絲來中斷大故障）。369個CT受到高電流持續(xù)1秒。CT能夠處理500 A（500 A相關(guān)CT初級額定值的100倍）。如果所需的持續(xù)時間小于1秒，耐受水平將增加。
b） CT尺寸和飽和度
繼電保護級CT的額定值（根據(jù)ANSI/IEEE C57.13.1）可采用以下格式給出：2.5C100、10T200、T1OO、10C50或C200。字母前面的數(shù)字表示最大比率修正；這個位置沒有號碼這意味著CT精度保持在10%的比率校正范圍內(nèi)，從0到20倍的額定值。
字母表示CT類型：?A‘C’（前身為L）表示在堆芯中泄漏通量較低的CT，對比率沒有明顯影響在等級和評級規(guī)定的范圍內(nèi)使用時?！癈”表示已計算；實際比率修正應(yīng)與計算的比率修正值相差不超過1%?！癈”型CT通常是具有均勻分布繞組的套管、窗口或條形CT。
?“T”（以前稱為H）表示一種CT，其核心具有高泄漏通量，對CT性能有顯著影響。“T”代表測試；由于比率校正是不可預(yù)測的，因此需要通過測試來確定?！癟”型CT是典型的初級繞組具有不均勻分布的繞組。隨后的數(shù)字規(guī)定了全繞組在20倍額定二次電流且不超過該比率的情況下可提供的二次端子電壓由評級的第一個數(shù)字指定的修正。（例如：10C100可以在20×5 a時產(chǎn)生100 V電壓，因此適當?shù)耐獠控摀?dān)為1? 或小于20倍額定二次電流，比率小于10%修正。）注意，電壓額定值位于CT的二次端子，內(nèi)部電壓降穿過CT的設(shè)計必須考慮二次電阻。有七種額定電壓：10、20、50、100、200、400和800。如果電流互感器接近更高的額定值，但未達到或超過該額定值，則電流互感器的額定值必須為較低的值。
為了確定CT可以輸出多少電流，需要CT的二次電阻。這種阻力將成為方程的一部分，以限制電流。這取決于CT二次側(cè)可能產(chǎn)生的最大電壓除以整個二次側(cè)電阻（包括CT二次電阻）。
a) 369 CT WITHSTAND
Withstand is important when the phase or ground CT has the capability of driving a large amount of current into the interposing CTs in the relay. This typically occurs on retrofit installations when the CTs are not sized to the burden of the relay. Electronic relays typically have low burdens (8 m? for 369), while the older electromechanical relays have typically high burdens (1 ?). For high current ground faults, the system will be either low resistance or solidly grounded. The limiting factor that determines the ground fault current that can flow in these types of systems is the source capacity. Withstand is not important for ground fault on high resistance grounded systems. On these systems, a resistor makes the connection from source to ground at the source (generator, transformer). The resistor value is chosen so that in the event of a ground fault, the current that flows is limited to a low value, typically 5, 10, or 20 A. Since the potential for very large faults exists (ground faults on high resistance grounded systems excluded), the fault must be cleared as quickly as possible. It is therefore recommended that the time delay for short circuit and high ground faults be set to instantaneous. Then the duration for which the 369 CTs subjected to high withstand will be less than 250 ms (369 reaction time is less than 50ms + breaker clearing time). Care must be taken to ensure that the interrupting device is capable of interrupting the potential fault. If not, some other method of interrupting the fault should be used, and the feature in question should be disabled (e.g. a fused contactor relies on fuses to interrupt large faults). The 369 CTs were subjected to high currents for 1 second bursts. The CTs were capable of handling 500 A (500 A relates to a 100 times the CT primary rating). If the time duration required is less than 1 second, the withstand level will increase.
b) CT SIZE AND SATURATION
The rating (as per ANSI/IEEE C57.13.1) for relaying class CTs may be given in a format such as: 2.5C100, 10T200, T1OO, 10C50, or C200. The number preceding the letter represents the maximum ratio correction; no number in this position implies that the CT accuracy remains within a 10% ratio correction from 0 to 20 times rating. The letter is an indication of the CT type: ? A 'C' (formerly L) represents a CT with a low leakage flux in the core where there is no appreciable effect on the ratio when used within the limits dictated by the class and rating. The 'C' stands for calculated; the actual ratio correction should be different from the calculated ratio correction by no more than 1%. A 'C' type CT is typically a bushing, window, or bar type CT with uniformly distributed windings. ? A 'T' (formerly H) represents a CT with a high leakage flux in the core where there is significant effect on CT performance. The 'T' stands for test; since the ratio correction is unpredictable, it is to be determined by test. A 'T' type CT is typically primary wound with unevenly distributed windings. The subsequent number specifies the secondary terminal voltage that may be delivered by the full winding at 20 times rated secondary current without exceeding the ratio correction specified by the first number of the rating. (Example: a 10C100 can develop 100 V at 20 × 5 A, therefore an appropriate external burden would be 1 ? or less to allow 20 times rated secondary current with less than 10% ratio correction.) Note that the voltage rating is at the secondary terminals of the CT and the internal voltage drop across the secondary resistance must be accounted for in the design of the CT. There are seven voltage ratings: 10, 20, 50, 100, 200, 400, and 800. If a CT comes close to a higher rating, but does not meet or exceed it, then the CT must be rated to the lower value. In order to determine how much current CTs can output, the secondary resistance of the CT is required. This resistance will be part of the equation as far as limiting the current flow. This is determined by the maximum voltage that may be developed by the CT secondary divided by the entire secondary resistance, CT secondary resistance included.
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