Chapter 6. Description of Operation of Protection Subsystem
M7IRDA2003I
7IRD-A/J/M: Distribution Protection & Control Terminal
© ZIV APLICACIONES Y TECNOLOGÍA, S.L.U. 2020
6-10
6.3
Open Phase Element
Without Minimum Load in the Line Setting
The Open Phase element is designed to detect an open phase in the monitored three-phase
circuit by measuring the ratio of the negative to positive sequence current. Figure 6-11 shows
the block diagram of this function.
Figure 6.7
Open Phase Element Block Diagram (without Minimum Load in the Line Setting).
Open Phase Pickup is initiated when this ratio exceeds the user adjustable setting. Once the
Open Phase element has picked up, output
T_FASE_A
is initiated. If the
T_FASE_A
signal is
present for a period of time equal to or greater than the
T_FASE_A
Time Delay setting, an
Open Phase Trip Output occurs.
The operation of this function is controlled by the element enable setting, the position of the
breaker and the positive sequence current level. If the breaker is open or the positive sequence
current level is less than 100 mA, the element is disabled. This function is also disabled when
any of the Phase or Ground, Time or Instantaneous Overcurrent elements are picked up.
If this function is disabled, positive and negative sequence current measurement is still provided
for metering display purposes.
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Страница 175: ...D List of Illustrations and Tables...