Name Type Values (Range) Unit DescriptionTRESLO INTEGER - - Estimated time to reset ofthe function (in min)TTRIPCAL INTEGER 0=Not Active1=Long Time2=Active- Calculated time status totrip: not active/long time/activeTRESCAL INTEGER 0=Not Active1=Long Time2=Active- Calculated time status toreset: not active/longtime/active8.7.7 Operation principleThe sampled analog phase currents are pre-processed and for each phase current thetrue RMS value of each phase current is derived. These phase current values are fedto the protection function.From the largest of the three phase currents a relative final temperature (heat content)is calculated according to the expression:2finalrefIIæ öQ = ç ÷ç ÷è øEQUATION1171 V1 EN (Equation 70)where:I is the largest phase currentIref is a given reference currentIf this calculated relative temperature is larger than the relative temperature levelcorresponding to the set operate (trip) current, then the start output signal START willbe activated.The actual temperature at the actual execution cycle is calculated as:If final nQ > QEQUATION1172 V1 EN (Equation 71)( )1 1 1tn n final n etD-- -æ öQ = Q + Q - Q × -ç ÷è øEQUATION1173 V1 EN (Equation 72)If final nQ < QEQUATION1174 V1 EN (Equation 73)Table continues on next pageSection 8 1MRK502052-UEN BCurrent protection404Technical manual
