Second Harmonic Blocking; Ref 2Nd Harmonic Blocking Logic; Figure 80: Ref 2Nd Harmonic Blocking Logic - GE P642 Technical Manual

P64x
4

SECOND HARMONIC BLOCKING

4.1

REF 2ND HARMONIC BLOCKING LOGIC

I fundamental HV
diff
Is-HS1
Low current (hard-coded )
I 2 harmonic HV
nd
diff
IH2 REF Set HV

Figure 80: REF 2nd harmonic blocking logic

P64x-TM-EN-1.3
&
&
I 2 nd harm / I fund
diff diff
Chapter 8 - Restricted Earth Fault Protection
Note: Same principle applies for LV and TV windings
REF IH2 Start HV
V00705
177