Second Harmonic Blocking Element - ABB REG650 Technical Manual

1MRK 502 048-UEN A
8.1.8
Technical manual
|I |
OP
Ix>
BLKSTx
BLOCK
DirModex=Off
DirModex=Non-directional
DirModex=Forward
DirModex=Reverse
IEC12000008 V2 EN
Figure 90: Simplified logic diagram for OC4PTOC

Second harmonic blocking element

A harmonic restrain of the Four step overcurrent protection function OC4PTOC can
be chosen. If the ratio of the 2nd harmonic component in relation to the fundamental
frequency component in the residual current exceeds the preset level defined by
parameter 2ndHarmStab setting, any of the four overcurrent stages can be selectively
blocked by parameter HarmRestrainx setting. When 2nd harmonic restraint feature is
active, the OC4PTOC function output signal 2NDHARMD will be set to logical value
one.
BLOCK
Extract second
I
OP harmonic current
component
Extract
fundamental
current component
IEC13000014 V1 EN
Figure 91: Second harmonic blocking
Characteristx=DefTime
a
a>b
b
AND
Characteristx=Inverse
OR STAGEx_DIR_Int
AND
OR
FORWARD_Int
AND
REVERSE_Int
0.07*IBase
X
2ndHarmStab
Section 8
Current protection
AND
tx
OR
tx
min
AND
Inverse
IEC12000008.vsd
a
a>b
b
a
a>b
b
AND
a
a>b
b
2ndH_BLOCK_Int
IEC13000014-1-en.vsd
STx
IEC12000008.vsd
185