ICST08A9工控备件机器人模块
打开此功能时必须小心。如果中断设备（接触器或断路器）的额定值不足以断开接地故障电流（低电阻或可靠接地系统），则应禁用该功能。或者，该特征可被分配给辅助继电器，并被连接，以使其跳闸能够断开故障电流的上游设备。各种情况（例如，接触器弹跳）可能会导致电机启动期间的瞬时接地电流在极短时间内超过接地故障拾取水平。接地故障时间延迟以10 ms为增量可调。延迟可以根据应用程序进行微调，使其响应速度仍然很快，但可以通过正常的操作干扰。通常，接地故障时间延迟设置得尽可能快，即0 ms。如果发生干扰跳闸，可能需要增加时间。当接地输入连接到剩余连接中的相CT时，必须特别小心。当电机启动时，启动电流（感应电机通常为6×FLA）具有不对称分量。这种不对称电流可能导致一个相位的RMS启动电流高达正常RMS启动电流的1.6倍。该瞬时DC分量将导致每个相CT的反应不同，并且进入469的接地输入的净电流将不可忽略。当电机启动时，接地故障元件的20毫秒阻断使469能够通过该瞬时接地电流信号。过载滤波器从故障发生时出现的不对称电流中去除了直流分量。这不会导致任何过度响应，然而，响应时间稍微变慢（10到15毫秒），但时间仍保持在规范范围内。注4-52 469电机管理继电器GE Power Management 4.7 S6电流元件4设定点编程4 4.7.7相位差这些设定点在使用差动功能时对差动元件进行编程。该功能由三个瞬时过电流元件组成，用于相位差动保护。差动保护可被视为相间或相间接地故障的第一线路保护。发生此类故障时，差动保护可限制可能发生的损坏。启用此功能时必须小心。如果中断装置（接触器或断路器）的额定值不足以断开潜在故障，则应禁用该功能。或者，该特征可被分配给辅助继电器，并被连接，以使其跳闸能够断开故障电流的上游设备。低电平差动故障可在瞬间发展为短路。一旦IaIN IaOUT、IbIN IbOUT或IcIN IcOUT（相位差）的幅值在延迟规定的时间段内超过拾取电平×差动CT一次电流，就会发生跳闸。为电机启动和运行条件提供单独的拾取水平和延迟。差动跳闸元件可编程为额定电流互感器的一部分。如果差动电流互感器以磁通平衡配置（3个电流互感器）连接，则可将其设置得更灵敏。如果在求和配置中使用6个CT，则在电机启动期间，每相上的两个CT的值可能不相等，因为CT不完全相同（不对称电流可能导致每相上CT具有不同的输出）。为防止该配置中的意外跳闸。
Care must be taken when turning On this feature. If the interrupting device (contactor or circuit breaker) is not rated to break ground fault current (low resistance or solidly grounded systems), the feature should be disabled. Alternately, the feature may be assigned to an auxiliary relay and connected such that it trips an upstream device that is capable of breaking the fault current. Various situations (e.g. contactor bounce) may cause transient ground currents during motor starting that may exceed the Ground Fault pickup levels for a very short period of time. The Ground Fault time delays are adjustable in 10 ms increments. The delay can be fine tuned to an application such that it still responds very fast, but rides through normal operational disturbances. Normally, the Ground Fault time delays are set as quick as possible, that is, 0 ms. Time may have to be increased if nuisance tripping occurs. Special care must be taken when the ground input is wired to the phase CTs in a residual connection. When a motor starts, the starting current (typically 6 × FLA for an induction motor) has an asymmetrical component. This asymmetrical current may cause one phase to see as much as 1.6 times the normal RMS starting current. This momentary DC component will cause each of the phase CTs to react differently and the net current into the ground input of the 469 will not be negligible. A 20 ms block of the ground fault elements when the motor starts enables the 469 to ride through this momentary ground current signal. The overreach filter removed the DC component from the asymmetrical current present at the moment a fault occurs. This results in no overreach whatsoever, however, the response time slows slightly (10 to 15 ms) but times still remain within specifications. NOTE 4-52 469 Motor Management Relay GE Power Management 4.7 S6 CURRENT ELEMENTS 4 SETPOINT PROGRAMMING 4 4.7.7 PHASE DIFFERENTIAL These setpoints program the differential element when the differential feature is in use. This feature consists of three instantaneous overcurrent elements for phase differential protection. Differential protection may be considered first line protection for phase to phase or phase to ground faults. In the event of such a fault, differential protection may limit the damage that may occur. Care must be taken when enabling this feature. If the interrupting device (contactor or circuit breaker) is not rated to break potential faults, the feature should be disabled. Alternately, the feature may be assigned to an auxiliary relay and connected such that it trips an upstream device that is capable of breaking the fault current. A low level differential fault can develop into a short circuit in an instant. A trip occurs once the magnitude of either IaIN-IaOUT, IbIN-IbOUT, or IcIN-IcOUT (phase differential) exceeds the Pickup Level × Differential CT Primary for a period of time specified by the delay. Separate pickup levels and delays are provided for motor starting and running conditions. The Differential trip element is programmable as a fraction of the rated CT. The level may be set more sensitive if the Differential CTs are connected in a flux balancing configuration (3 CTs). If 6 CTs are used in a summing configuration, the values from the two CTs on each phase during motor starting may not be equal since the CTs are not perfectly identical (asymmetrical currents may cause the CTs on each phase to have different outputs). To prevent nuisance tripping in this configuration, the STARTING DIFF.
