ICS TRIPLEX T8153模塊控制器
WO-相CT配置B.1.1描述本附錄說(shuō)明了如何使用兩個(gè)CT來(lái)感測三相電流。顯示了使用兩個(gè)CT而不是三個(gè)CT來(lái)檢測相電流的正確配置。兩個(gè)CT中的每一個(gè)都充當電流源。從A相CT流出的電流流入標記為A的繼電器上的插入式CT。從那里，電流與從C相CT流出、剛剛通過(guò)標記為C的繼電器上插入式CT的電流相加。該“相加”電流流過(guò)標記為B的插入式電流，電流分裂以返回到其各自的源（CT）。極性非常重要，因為相位B的值必須是A+C的負等效值，以便所有矢量的和等于零。注意，如圖所示，只有一個(gè)接地連接。如果進(jìn)行了兩個(gè)接地連接，則已創(chuàng )建電流的并行路徑。在雙CT配置中，電流將在兩個(gè)CT的公共點(diǎn)矢量相加。該圖說(shuō)明了兩種可能的配置。如果在已知平衡的系統上，一個(gè)相位讀數高達1.73倍，只需反轉兩個(gè)相位CT之一處的導線(xiàn)極性（注意CT在某一點(diǎn)仍接地）。極性很重要。A B C A B C：5:5:5:COM:COM:COM B-2 469電機管理繼電器GE電源管理B.1兩相CT配置附錄B B為了進(jìn)一步說(shuō)明這一點(diǎn)，下圖顯示了A相和C相的電流如何相加以創(chuàng )建“B”相。再一次，如果其中一個(gè)相位的極性相差180°，則平衡系統上產(chǎn)生的矢量的大小將相差1.73倍。在三線(xiàn)電源上，此配置將始終有效，并且將正確檢測不平衡。在單相情況下，繼電器的插入CT處始終存在較大的不平衡。例如，如果相位A丟失，相位A將讀取零，而相位B和C都將讀取相位C的大小。如果另一方面，相位B丟失，則在供電時(shí)，相位A與相位C將相差180°，并且相位B的矢量相加將等于零。GE Power Management 469電機管理繼電器C-1附錄C C.1冷卻時(shí)間常數的選擇C附錄C附錄CC.1冷卻時(shí)間常數選擇C.1.1說(shuō)明熱極限不是一門(mén)黑白科學(xué)，設置保護繼電器熱模型有一定的藝術(shù)性。熱極限的定義對不同的制造商來(lái)說(shuō)意味著(zhù)不同的事情，而且通常情況下，信息是不可用的。因此，記住
WO-PHASE CT CONFIGURATION B.1.1 DESCRIPTION This appendix illustrates how two CTs may be used to sense three phase currents. The proper configuration for the use of two CTs rather than three to detect phase current is shown. Each of the two CTs acts as a current source. The current that comes out of the CT on phase A flows into the interposing CT on the relay marked A. From there, the current sums with the current that is flowing from the CT on phase C which has just passed through the interposing CT on the relay marked C. This ‘summed’ current flows through the interposing CT marked B and from there, the current splits up to return to its respective source (CT). Polarity is very important since the value of phase B must be the negative equivalent of A + C in order for the sum of all the vectors to equate to zero. Note that there is only one ground connection as shown. If two ground connections are made, a parallel path for current has been created. In the two CT configuration, the currents will sum vectorially at the common point of the two CTs. The diagram illustrates the two possible configurations. If one phase is reading high by a factor of 1.73 on a system that is known to be balanced, simply reverse the polarity of the leads at one of the two phase CTs (taking care that the CTs are still tied to ground at some point). Polarity is important. A B C A B C :5 :5 :5 :COM :COM :COM B-2 469 Motor Management Relay GE Power Management B.1 TWO-PHASE CT CONFIGURATION APPENDIX B B To illustrate the point further, the diagram below shows how the current in phases A and C sum up to create phase 'B'. Once again, if the polarity of one of the phases is out by 180°, the magnitude of the resulting vector on a balanced system will be out by a factor of 1.73. On a three wire supply, this configuration will always work and unbalance will be detected properly. In the event of a single phase, there will always be a large unbalance present at the interposing CTs of the relay. If for example phase A was lost, phase A would read zero while phases B and C would both read the magnitude of phase C. If on the other hand, phase B was lost, at the supply, phase A would be 180° out-of-phase with phase C and the vector addition would equal zero at phase B. GE Power Management 469 Motor Management Relay C-1 APPENDIX C C.1 SELECTION OF COOL TIME CONSTANTS C APPENDIX C APPENDIX CC.1 SELECTION OF COOL TIME CONSTANTS C.1.1 DESCRIPTION Thermal limits are not a black and white science and there is some art to setting a protective relay thermal model. The definition of thermal limits mean different things to different manufacturers and quite often, information is not available. Therefore, it is important to remember what the
