Application
The RCS-993 relay is a digital out-of-step protection to initialize tripping for power grid stability. In case of out-of-step, it takes corresponding measurements: isolating grid islands, shutting generators, shedding load or starting other control provisions to bring the system back to synchronization again. The function of these actions are to avoid the collapse of power system.
Functional Block Diagram
Functions
l Out-of-step protection. (78)
l Quick stage of the out-of-step. (78)
l Slow stage of the out-of-step. (78)
l CT failure detection logic.
l VT failure detection logic.
l Voltage and current drift auto adjustment.
l Self diagnostic test.
l GPS clock synchronization.
l Fault Recorder.
l 128 event reports.
l High resolution oscillography of last 24 oscillograms. (Compatible with international COMTRADE format)
l Rear communication ports: Ethernet (Optional) or 2 RS-485 with IEC 60870-5-103 protocol, 1 RS-485 with clock synchronization, 1 RS-232 or RS-485 with printer.
l Front communication port: 1 RS-232 for testing and setting.
Features
l Determine out-of-step of power system based on the variation trace of and use the minimum voltage value measured at the place where the device is located to determine the operation region.
l Quick stage of the out-of-step relay can measure loss of synchronism whose period is over 200ms, initialize tripping in the first asynchronous cycle.
l Slow stage of the out-of-step relay can measure loss of synchronism whose period is over 100ms. And tripping time could be configured as between the 2nd and 15th cycle.
l Loss of synchronism discrimination adopts the impedance sequential discrimination method, as shown in 6 zones on impedance plane.
l The patented adaptive floating threshold method is adopted, which is insensitive to system unbalance and disturbance. The measuring element can get both high security and high speed simultaneously.
l Innovative technology to prevent any undesired trip caused by any component failure is adopted. The relay has two independent data acquisition paths, one for a fault detector and the other for protection and its logic. Tripping outputs are supervised by the fault detector to prevent a mal-operation.
l The connector type can be selected as connectorized wiring connector and crimp terminal connector. The unique connectorized wiring connectors from the relay rear panel to the terminal blocks on the rack or cabinet makes the on-site commissioning and replacement much easier than when you do the commissioning using the traditional screw terminals on the rear panel.
l The relay provides GPS clock synchronization, including second pulse, minute pulse, and IRIG-B synchronization.
l The relay is compatible with multiple protocols- IEC61850 and IEC 60870-5-103. The RCS-901 provides networking interface such as RS485, RS232 and Ethernet port.
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