en05000016.vsdVoltageIDMT VoltageTimeUL1UL2UL3IEC05000016 V1 ENFigure 117: Voltage used for the inverse time characteristic integrationA TRIP requires that the overvoltage condition continues for at least the user settime delay. This time delay is set by the parameter t1 and t2 for definite time mode(DT) and by selected voltage level dependent time curves for the inverse timemode (IDMT). If the START condition, with respect to the measured voltageceases during the delay time, the corresponding START output is reset.8.2.7.3 BlockingIt is possible to block two step overvoltage protection (OV2PTOV) partially orcompletely, by binary input signals where:BLOCK: blocks all outputsBLKST1: blocks all start and trip outputs related to step 1BLKST2: blocks all start and trip outputs related to step 28.2.7.4 DesignThe voltage measuring elements continuously measure the three phase-to-earthvoltages or the three phase-to-phase voltages. Recursive Fourier filters filter theinput voltage signals. The phase voltages are individually compared to the setvalue, and the highest voltage is used for the inverse time characteristic integration.A special logic is included to achieve the 1 out of 3, 2 out of 3 or 3 out of 3 criteriaSection 8 1MRK 502 034-UEN -Voltage protection228Technical Manual
