GE MiCOM P143 Agile User Manual

15.2 SECOND HARMONIC BLOCKING LOGIC (POC INPUT)
V00626
I>Lift 2H
Low current (hard-coded)
IA 2
nd
harm / IA fund
&
&
2ndHarm Thresh
IA2H Start
IB2H Start
1
&
I2H Any Start
IC2H Start
&
I>Lift 2H
&
2ndHarm Thresh
&
I>Lift 2H
&
2ndHarm Thresh
&
Low current (hard-coded)
Low current (hard-coded)
IB 2
nd
harm / IB fund
IC 2
nd
harm / IC fund
IA fundamental
IA 2ndHarm
IA fundamental
IB 2ndHarm
IC 2ndHarm
IC 2ndHarm
Figure 76: 2nd Harmonic Blocking Logic (POC Input)
The function w
orks by identifying and measuring the inrush currents present in the phase currents at switch on. It
does this by comparing the value of the second harmonic current components to the value of the fundamental
component. If this ratio exceeds the set thresholds, then the blocking signal is generated. The threshold is defined
by the 2ndHarm Thresh setting.
We only want the function to block the protection if the fundamental current component is within the normal
range. If this exceeds the normal range, then this is indicative of a fault, which must be protected. For this reason
there is another settable trigger I>lift 2H, which when exceeded, stops the 2nd harmonic blocking function.
Chapter 6 - Current Protection Functions P14x
150 P14xEd1-TM-EN-1

GE MiCOM P143 Agile Specifications

General

Brand	GE
Model	MiCOM P143 Agile
Category	Control Unit
Language	English