Instruction manual
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AQ F3x0 Feeder protection IED
29 (162
)
3.2.3
T
HREE
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PHASE TIME OVERCURRENT
I>,
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(50/51)
Three phase time overcurrent function includes the definite time and IDMT characteristics
according to the IEC and IEEE standards. The function measures the fundamental Fourier
components of the measured three phase currents.
The structure of the algorithm consists of following modules. Fourier calculation module
calculates the RMS values of the Fourier components of the 3-phase currents.
Characteristics module compares the Fourier basic harmonic components of the phase
currents into the setting value. Decision logic module generates the trip signal of the
function.
In the figure below is presented the structure of the time overcurrent algorithm.
Figure 3-12 Structure of the time overcurrent algorithm.
The algorithm generates a start signal based on the Fourier components of the phase
currents or peak values of the phase currents in case if the user set pick-up value is
exceeded. Trip signal is generated based into the selected definite time- or IDMT additional
time delay is passed from the start conditions. The operation of the function is phase wise
and it allows each phase to be tripped separately. Standard operation is three poles.
The function includes a blocking signal input which can be configured by user from either
IED internal binary signals or IED binary inputs through the programmable logic.
Operating characteristics of the definite time is presented in the figure below.
Содержание AQ F3 0 Series
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Страница 150: ...Instruction manual AQ F3x0 Feeder protection IED 150 162 Figure 6 5 Panel cut out and spacing of the AQ 39x IED ...