GE Multilin B90 Low Impedance Bus Differential System 5-35 SETTINGS 5.1 OVERVIEW55.1.2 INTRODUCTION TO ELEMENTSIn the design of UR relays, the term element is used to describe a feature that is based around a comparator. The compar-ator is provided with an input (or set of inputs) that is tested against a programmed setting (or group of settings) to deter-mine if the input is within the defined range that will set the output to logic 1, also referred to as setting the flag. A singlecomparator may make multiple tests and provide multiple outputs; for example, the time overcurrent comparator sets apickup flag when the current input is above the setting and sets an operate flag when the input current has been at a levelabove the pickup setting for the time specified by the time-current curve settings. All comparators use analog parameteractual values as the input.The exception to the above rule are the digital elements, which use logic states as inputs.Elements are arranged into two classes, grouped and control. Each element classed as a grouped element is provided withsix alternate sets of settings, in setting groups numbered 1 through 6. The performance of a grouped element is defined bythe setting group that is active at a given time. The performance of a control element is independent of the selected activesetting group.The main characteristics of an element are shown on the element logic diagram. This includes the inputs, settings, fixedlogic, and the output operands generated (abbreviations used on scheme logic diagrams are defined in Appendix F).Some settings for current and voltage elements are specified in per-unit (pu) calculated quantities:pu quantity = (actual quantity) / (base quantity)For current elements, the base quantity is the nominal secondary or primary current of the CT.For voltage elements the base quantity is the nominal primary voltage of the protected system which corresponds (basedon VT ratio and connection) to secondary VT voltage applied to the relay.For example, on a system with a 13.8 kV nominal primary voltage and with 14400:120 V delta-connected VTs, the second-ary nominal voltage (1 pu) would be: REMOTE OUTPUTS UserSt BIT PAIRS See page 5-136. RESETTING See page 5-136. DIRECT INPUTS See page 5-136. DIRECT OUTPUTS See page 5-137. IEC 61850 GOOSE ANALOGS See page 5-140. IEC 61850 GOOSE UINTEGERS See page 5-141. SETTINGS TESTINGTEST MODEFUNCTION: Disabled See page 5-142.TEST MODE FORCING:On See page 5-142. FORCE CONTACT INPUTS See page 5-143. FORCE CONTACT OUTPUTS See page 5-144.NOTE
