ABB Relion 650 Series Technical Manual page 184

Section 6
Current protection
6.6.7.6 Four residual overcurrent steps
Each overcurrent step uses operating quantity Iop (residual current) as measuring quantity. Each
of the four residual overcurrent steps has the following built-in facilities:
• Directional mode can be set to
setting the directional mode of the step is selected. It shall be noted that the directional
decision (Forward/Reverse) is not made within each residual overcurrent step itself. The
direction of the fault is determined in a directional element common for all steps.
• Residual current pickup value.
• Type of operating characteristic. By this parameter setting it is possible to select inverse or
definitive time delay for step 1 and 4 separately. Step 2 and 3 are always definite time delayed.
All of the standard IEC and ANSI inverse characteristics are available. For the complete list of
available inverse curves please refer to section
• Time delay related settings. By these parameter settings the properties like definite time
delay, minimum operating time for inverse curves and reset time delay are defined.
• Supervision by second harmonic blocking feature (
setting it is possible to prevent operation of the step if the second harmonic content in the
residual current exceeds the preset level.
Simplified logic diagram for one residual overcurrent step is shown in figure 92.
ANSI09000638 V1 EN-US
Figure 92: Simplified logic diagram for residual overcurrent step n= step 1 and 4
The protection can be completely blocked from the binary input BLOCK. Output signals for
respective step, PUSTx and TRSTx, can be blocked from the binary input BLKn.
6.6.7.7 Directional supervision element with integrated directional comparison
function
178
|I |
OP
Pickupx
BLKx
BLOCK
2ndH_BLOCK_Int
OR
HarmRestrainx=Disabled
DirModeSelx=Disabled
DirModeSelx=Non-directional
DirModeSelx=Forward
FORWARD_Int
DirModeSelx=Reverse
It shall be noted that at least one of the four residual overcurrent steps shall be set
as directional in order to enable execution of the directional supervision element
and the integrated directional comparison function.
© Copyright 2011 ABB Power Grids. All rights reserved
Disabled / Non-directional / Forward / Reverse . By this parameter
"Inverse time
Enabled / Disabled ). By this parameter
Characteristn=DefTime
a
a>b
b
AND
Characteristn=Inverse
OR STEPx_DIR_Int
AND
OR
AND
REVERSE_Int
characteristics".
tx
OR
Inverse
ANSI09000638-1-en.vsd
Line distance protection REL650
1MRK 506 326-UUS B
M13941-166 v5
PUST
x
M13941-179 v4
Technical manual