ICS TRIPLEX T8153模块控制器
WO-相CT配置B.1.1描述本附录说明了如何使用两个CT来感测三相电流。显示了使用两个CT而不是三个CT来检测相电流的正确配置。两个CT中的每一个都充当电流源。从A相CT流出的电流流入标记为A的继电器上的插入式CT。从那里，电流与从C相CT流出、刚刚通过标记为C的继电器上插入式CT的电流相加。该“相加”电流流过标记为B的插入式电流，电流分裂以返回到其各自的源（CT）。极性非常重要，因为相位B的值必须是A+C的负等效值，以便所有矢量的和等于零。注意，如图所示，只有一个接地连接。如果进行了两个接地连接，则已创建电流的并行路径。在双CT配置中，电流将在两个CT的公共点矢量相加。该图说明了两种可能的配置。如果在已知平衡的系统上，一个相位读数高达1.73倍，只需反转两个相位CT之一处的导线极性（注意CT在某一点仍接地）。极性很重要。A B C A B C：5:5:5:COM:COM:COM B-2 469电机管理继电器GE电源管理B.1两相CT配置附录B B为了进一步说明这一点，下图显示了A相和C相的电流如何相加以创建“B”相。再一次，如果其中一个相位的极性相差180°，则平衡系统上产生的矢量的大小将相差1.73倍。在三线电源上，此配置将始终有效，并且将正确检测不平衡。在单相情况下，继电器的插入CT处始终存在较大的不平衡。例如，如果相位A丢失，相位A将读取零，而相位B和C都将读取相位C的大小。如果另一方面，相位B丢失，则在供电时，相位A与相位C将相差180°，并且相位B的矢量相加将等于零。GE Power Management 469电机管理继电器C-1附录C C.1冷却时间常数的选择C附录C附录CC.1冷却时间常数选择C.1.1说明热极限不是一门黑白科学，设置保护继电器热模型有一定的艺术性。热极限的定义对不同的制造商来说意味着不同的事情，而且通常情况下，信息是不可用的。因此，记住
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
