产品细节介绍
1VCR007346操作面板
启动时，涌入电流非常高，导致热容量迅速增加。使用的热容量
变量与启动电机所需的热容量进行比较。如果没有足够的热量
369可用于启动电机，在电机冷却至热容量水平才能成功启动之前，它会阻止操作员启动。假设电机需要40%的热容量才能启动。如果电机在停止前过载运行热容量会有一定值；比如说80%。在这种情况下，369（启用启动禁止）将锁定或防止操作员启动电机，直到热容量降低到60%，以便成功启动电机可以实现启动。该示例如第7-19页的图7-7:START INHIBIT FUNCTIONALITY（起动抑制功能示意图）所示。本节说明了如何使用两个CT感应三相电流。
使用两个CT而不是三个CT检测相电流的正确配置如下所示。两个CT中的每一个充当电流源。来自“A”相CT的电流流入标记为“A”的继电器上的插入式CT。从…起在这里，它与刚刚通过插入式CT的相位“C”上CT的电流相加
标记为“C”的继电器。该“总和”电流流过标记为“B”的插入式CT，然后从该处分裂返回
其各自的来源（CT）。极性非常重要，因为相位“B”的值必须等于“A”+“C”表示所有矢量的总和等于零。请注意，只有一个接地连接。做两个接地连接为电流创建了一条平行路径。在三线电源上，此配置将始终工作，并且将正确检测不平衡。如果发生单个相位，继电器的插入CT将始终存在较大的不平衡。例如，如果相位“A”丢失，
相位“A”读数为零，而相位“B”和“C”均读数为相位“C”的幅值。另一方面，阶段
“B”丢失，在电源处，“A”将与相位“C”相异180×，相位“B”的矢量相加将为零。
7.6.8未接地系统接地故障检测
50:0.025接地故障输入用于灵敏地检测高电阻接地系统的故障。检测1至10 A初级接地电流转换为输入0.5 mA至5 mA至50:0.025抽头。理解力这允许以简单的方式使用此输入来检测未接地系统上的接地故障。
下图说明了如何使用星形开口三角形电压互感器配置来检测相位接地。
正常情况下，50:0.025输入端和电阻器之间出现的三相净电压为接近于零。在故障条件下，假设VT的二次侧电压为69 V，则继电器看到的净电压电阻器为3Vo或3×69 V=207 V。369需要从每个RTD带回三根引线：热、回路和补偿。在某些情况下可能很贵。然而，可以减少引线的数量，以便第一个RTD需要三根引线每个连续RTD只有一个。接线配置见下图。
Upon a start, the inrush current
is very high, causing the thermal capacity to rapidly increase. The Thermal Capacity Used variable is compared to the amount of the Thermal Capacity required to start the motor. If there is not enough thermal capacity available to start the motor, the 369 blocks the operator from starting until the motor has cooled to a level of thermal capacity to successfully start. Assume that a motor requires 40% Thermal Capacity to start. If the motor was running in overload prior to stopping, the thermal capacity would be some value; say 80%. Under such conditions the 369 (with Start Inhibit enabled) will lockout or prevent the operator from starting the motor until the thermal capacity has decreased to 60% so that a successful motor start can be achieved. This example is illustrated in Figure 7–7: ILLUSTRATION OF THE START INHIBIT FUNCTIONALITY on page 7–19.
This section illustrates how to use two CTs to sense three phase currents.
The proper configuration for using two CTs rather than three to detect phase current is shown below. Each of the two CTs acts as a current source. The current from the CT on phase ‘A’ flows into the interposing CT on the relay marked ‘A’. From there, the it sums with the current 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 splits from there 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' for the sum of all the vectors to equate to zero. Note that there is only one ground connection. Making two ground connections creates a parallel path for the current
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, ‘A’ would be 180× out of phase with phase ‘C’ and the vector addition would be zero at phase ‘B’. 7.6.8 GROUND FAULT DETECTION ON UNGROUNDED SYSTEMS The 50:0.025 ground fault input is designed for sensitive detection of faults on a high resistance grounded system. Detection of ground currents from 1 to 10 A primary translates to an input of 0.5 mA to 5 mA into the 50:0.025 tap. Understanding this allows the use of this input in a simple manner for the detection of ground faults on ungrounded systems. The following diagram illustrates how to use a wye-open delta voltage transformer configuration to detect phase grounding. Under normal conditions, the net voltage of the three phases that appears across the 50:0.025 input and the resistor is close to zero. Under a fault condition, assuming the secondaries of the VTs to be 69 V, the net voltage seen by the relay and the resistor is 3Vo or 3 × 69 V = 207 V.
The 369 requires three leads to be brought back from each RTD: Hot, Return, and Compensation. In certain situations this can be quite expensive. However, it is possible to reduce the number of leads so that three are required for the first RTD and only one for each successive RTD. Refer to the following diagram for wiring configuration.
公司主营产品图展示
产品优势
1：国外专业的供货渠道，具有价格优势
2：产品质量保证，让您售后无忧
3：全国快递包邮
4：一对一服务
公司主营范围简介
PLC可编程控制器模块，DCS卡件，ESD系统卡件，振动监测系统卡件，汽轮机控制系统模块，燃气发电机备件等，优势品牌：Allen Bradley、BentlyNevada、ABB、Emerson Ovation、Honeywell DCS、Rockwell ICS Triplex、FOXBORO、Schneider PLC、GE Fanuc、Motorola、HIMA、TRICONEX、Prosoft等各种进口工业零部件、欧美进口模块。
产品广泛应用于冶金、石油天然气、玻璃制造业、铝业、石油化工、煤矿、造纸印刷、纺织印染、机械、电子制造、汽车制造、塑胶机械、电力、水利、水处理/环保、锅炉供暖、能源、输配电等等
