GE UR Series Instruction Manual

Also see for L90: Communications manual Communications guide Instruction manual Instruction manual Instruction manual

Contents

5-90L90 Line Differential RelayGE Power Management5.5 GROUPED ELEMENTS 5 SETTINGS5To increase security for three phase faults very close to the location of the VTs used to measure the polarizing voltage, a‘voltage memory’ feature is incorporated. This feature remembers the measurement of the polarizing voltage the momentbefore the voltage collapses, and uses it to determine direction. The voltage memory remains valid for one second after thevoltage has collapsed.The main component of the phase directional element is the phase angle comparator with two inputs: the operating signal(phase current) and the polarizing signal (the line voltage, shifted in the leading direction by the characteristic angle, ECA).The following table shows the operating and polarizing signals used for phase directional control:MODE OF OPERATION:• When the Phase Directional function is "Disabled", or the operating current is below 5% × CT Nominal, the elementoutput is "0".• When the Phase Directional function is "Enabled", the operating current is above 5% × CT Nominal and the polarizingvoltage is above the set threshold, the element output depends on the phase angle between the operating and polariz-ing signals as follows:– The element output is logic "0" when the operating current is within polarizing voltage ±90°.– For all other angles, the element output is logic "1".• Once the voltage memory has expired, the phase overcurrent elements under directional control can be set to block ortrip on overcurrent as follows:– When BLOCK WHEN V MEM EXP is set to "Yes", the directional element will block the operation of any phase overcur-rent element under directional control when voltage memory expires. When set to "No", the directional elementallows tripping of phase overcurrent elements under directional control when voltage memory expires.In all cases, directional blocking will be permitted to resume when the polarizing voltage becomes greater than the "polariz-ing voltage threshold".SETTINGS:PHASE DIR 1 SIGNAL SOURCE:This setting is used to select the source for the operating and polarizing signals.The operating current for the phase directional element is the phase current for the selected current source. The polarizingvoltage is the line voltage from the phase VTs, based on the 90° or "quadrature" connection and shifted in the leading direc-tion by the Element Characteristic Angle (ECA).PHASE DIR 1 ECA:This setting is used to select the Element Characteristic Angle, i.e. the angle by which the polarizing voltage is shifted in theleading direction to achieve dependable operation. In the design of UR elements, a block is applied to an element byasserting logic 1 at the blocking input. This element should be programmed via the ECA setting so that the output is logic 1for current in the non-tripping direction.PHASE DIR 1 POL V THRESHOLD:This setting is used to establish the minimum level of voltage for which the phase angle measurement is reliable. The set-ting is based on VT accuracy. The default value is 0.05 pu.PHASE DIR 1 BLOCK WHEN V MEM EXP:This setting is used to select the required operation upon expiration of voltage memory. When set to "Yes", the directionalelement blocks the operation of any phase overcurrent element under directional control, when voltage memory expires;when set to "No", the directional element allows tripping of phase overcurrent elements under directional control.PHASE OPERATINGSIGNALPOLARIZING SIGNAL VPOLABC PHASE SEQUENCE ACB PHASE SEQUENCEA Angle of IA Angle of VBC × (1∠ECA) Angle of VCB × (1∠ECA)B Angle of IB Angle of VCA × (1∠ECA) Angle of VAC × 1∠ECA)C Angle of IC Angle of VAB × (1∠ECA) Angle of VBA × (1∠ECA)