Hysteresis - DEMA 400 Series User Manual

until the end of this period, the protection function trip time counter will be reseted. Reset
delay thresholds are in the range of (0-60).
4.3.3.1.5

Hysteresis

It allows the selection of the minimum and maximum values for the protection to be activated
by entering the value in percentages and the same value being switched off in percentage. For
example, if the overvoltage protection start value is set to 100 V, the hysteresis value is set to
5%, the protection is activated when the protection exceeds 105 V; If it falls below 95 V, the
protection is deactivated. This hysteresis value can be selected from 1% to 20%.
4.3.3.1.6 Measurement Mode
The measurement mode can be selected as RMS or Basic Sequence. The basic sequence
measurement is selected to use of nominal measurement values. The RMS measurement is
selected to use the values calculated by taking the square root of the mean of the squares of
the measured values. This value is also called Active or Effective value.
4.3.3.1.7 Phase Operation Mode
It is the section where the single phase or three phase is chosen for the system.
4.3.3.2 27- Under Voltage Protection
The overvoltage protection settings are located Menu> Protection Settings> Voltage
Protection Settings> Undervoltage Protection
Undervoltage protection is used for protection from faults caused by voltage drop in the
engine, network. The protection is activated when the mains voltage to which the motor is
supplied falls below the protection field set via the relay. This protection operates with phase-
phase voltage information.
Directional phase overcurrent protection is indicated by U< and U<< in IEC 60617
Standards; PHI_PIUV_1 and PHI_PIUV_2 in IEC 61850; 27-I-1 ve 27-I-2 in IEEE/ANSI
Standards.
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