GE B30 Instruction Manual

Also see for b30: Maintenance manual Instruction manual Instruction manual Communications manual Instruction manual

Contents

GE B30 Instruction Manual Manual pdf 35 page image

GE Multilin B30 Bus Differential System 2-12 PRODUCT DESCRIPTION 2.1 INTRODUCTION22 PRODUCT DESCRIPTION 2.1INTRODUCTION 2.1.1 OVERVIEWThe B30 Bus Differential System is a microprocessor-based relay that provides protection and metering for a busbar withup to six feeders. Protection is provided by a low impedance percent differential element with features that make it immuneto CT saturation. Both biased (restrained) and unbiased (unrestrained) differential protection functions are provided.A dynamic busbar replica mechanism is provided by associating the breaker and switch status signals with the differentialzone currents.The biased bus differential function operates using both the differential and current directional comparison protection princi-ples. The differential element uses a dual-slope dual-breakpoint characteristic with the restraining current formed as a max-imum of the input currents for better stability during through-fault conditions and faster operation on internal faults. Thecurrent directional comparison principle checks the angular relationship between the currents.The biased bus differential protection operates in the two-out-of-two mode for low differential currents. This improves stabil-ity during CT saturation conditions caused by comparatively low currents combined with unfavorable phenomena such asmultiple auto-reclose actions. For high differential currents, the bus differential element operates using the differential char-acteristic alone if CT saturation is not detected. Upon CT saturation detection, the relay switches to the two-out-of-twooperating mode for better through fault stability.The B30 typical operating time is about 12 ms for fast form-C output contacts and internal usage by user-programmablelogic, and about 15 ms for trip-rated form-A output contacts.A CT failure alarm function that monitors the level of the differential current is provided. A situation when the differential cur-rent stays above a pre-defined level for a pre-defined period of time is declared as a CT trouble event, and an alarm israised. To prevent false tripping due to CT trouble, undervoltage supervision or an external check zone can be used.Voltage and current metering is built into the relay as a standard feature. Current parameters are available as total wave-form RMS magnitude, or as fundamental frequency only RMS magnitude and angle (phasor).Diagnostic features include an event recorder capable of storing 1024 time-tagged events and oscillography capable ofstoring up to 64 records with programmable trigger, content and sampling rate.The internal clock used for time-tagging canbe synchronized with an IRIG-B signal or via the SNTP protocol over the Ethernet port. This precise time stamping allowsthe sequence of events to be determined throughout the system. Events can also be programmed (via FlexLogic equa-tions) to trigger oscillography data capture that can be set to record the measured parameters before and after the event forviewing on a computer. These tools significantly reduce troubleshooting time and simplify report generation in the event ofa system fault.Several options are available for communication. A faceplate RS232 port can be used to connect to a computer for the pro-gramming of settings and the monitoring of actual values. The RS232 port has a fixed baud rate of 19.2 kbps. The rearRS485 port allows independent access by operating and engineering staff. It can be connected to system computers withbaud rates up to 115.2 kbps. All serial ports use the Modbus RTU protocol. The 100Base-FX Ethernet interface providesfast, reliable communications in noisy environments. The Ethernet port supports IEC 61850, Modbus/TCP, TFTP protocols,PTP (according to IEEE Std. 1588-2008 or IEC 61588), and allows access to the relay via any standard web browser (B30web pages). The IEC 60870-5-104 protocol is supported on the Ethernet port, and DNP 3.0 and IEC 60870-5-104 cannotbe enabled at the same time.The B30 IEDs use flash memory technology that allows field upgrading as new features are added. The following Singleline diagram illustrates the relay functionality using American National Standards Institute (ANSI) device numbers.Table 2–1: ANSI DEVICE NUMBERS AND FUNCTIONSDEVICENUMBER FUNCTION DEVICENUMBER FUNCTION27P Phase undervoltage 51G Ground time overcurrent50BF Breaker failure 51N Neutral time overcurrent50G Ground instantaneous overcurrent 51P Phase time overcurrent50N Neutral instantaneous overcurrent 51_2 Negative-sequence time overcurrent50P Phase instantaneous overcurrent 59N Neutral overvoltage50_2 Negative-sequence instantaneous overcurrent 59X Auxiliary overvoltage50/74 CT trouble 87B Restrained bus differential50/87 Unrestrained bus differential