one. Reset of the start and trip signal can be instantaneous or time delay inaccordance with the setting.6.1.7.5 Built-in overvoltage protection steps M13751-234 v3Two overvoltage protection steps are available. They are absolutely identical andtherefore only one will be explained here.Overvoltage step simply compares the magnitude of the measured voltage quantity(see table 40) with the set pickup level. The overvoltage step will pickup if themagnitude of the measured voltage quantity is bigger than this set level.The start signal will start definite time delay or inverse (IDMT) time delay inaccordance with the end user setting. If the start signal has value one for longertime than the set time delay, the overvoltage step will set its trip signal to one.Reset of the start and trip signal can be instantaneous or time delay in accordancewith the end user setting.6.1.7.6 Built-in undervoltage protection steps M13751-239 v3Two undervoltage protection steps are available. They are absolutely identical andtherefore only one will be explained here.Undervoltage step simply compares the magnitude of the measured voltagequantity (see table 40) with the set pickup level. The undervoltage step will pickupif the magnitude of the measured voltage quantity is smaller than this set level.The start signal will start definite time delay or inverse (IDMT) time delay inaccordance with the end user setting. If the start signal has value one for longertime than the set time delay, the undervoltage step will set its trip signal to one.Reset of the start and trip signal can be instantaneous or time delay in accordancewith the end user setting.6.1.7.7 Logic diagram M13085-3 v7The simplified internal logics, for CVGAPC function are shown in the followingfigures.The following currents and voltages are inputs to the multipurpose protectionfunction. They must all be expressed in true power system (primary) Amperes andkilovolts.1. Instantaneous values (samples) of currents & voltages from one three-phasecurrent and one three-phase voltage input.2. Fundamental frequency phasors from one three-phase current and one three-phase voltage input calculated by the pre-processing modules.3. Sequence currents & voltages from one three-phase current and one three-phase voltage input calculated by the pre-processing modules.Section 6 1MRK 511 424-UEN BMultipurpose protection102 Bay control REC650 2.2 IECTechnical manual
