ABB RER620 - Page 261

1MAC309294-MB F Section 4
Protection functions
RER620 255
Technical Manual
Table 267: Fault identification
Once the specific fault type is determined, the respective fault loop voltage and current
phasor are taken for fault location algorithm.
If the fault is any single phase to ground fault, then the respective phase current should be
ground compensated.
The procedure for the ground compensation is given below,
For ground fault cases, the current measured at the relay is ground compensated by
employing the following formula:
Equation (37)
where
Equation (38)
k = 1.0 (scaling factor)
ZL
pos
and ZL
zero
refer to positive and zero sequence line impedances.
ZL
pos
= RL
pos
+ j*XL
pos
ZL
zero
= RL
zero
+ j*XL
zero
RL
pos
= PosSeqR * LinLen
XL
pos
= PosSeqX * LinLen
RL
zero
= ZeroSeqR * LinLen
XL
zero
= ZeroSeqX * LinLen
= Ground compensated phase current
= Non-compensated phase current
Fault in phase A Fault in phase B Fault in phase C Fault in ground (Io) FLTLOOP FLTLOOP
1 0 0 1 AG Fault 1
0 1 0 1 BG Fault 2
001 1CG Fault 3
1 1 0 1 AB Fault 4
0 1 1 1 BC Fault 5
1 0 1 1 CA Fault 6
1 1 1 1 ABC Fault 7
1 1 0 0 ABG Fault -1
0 1 1 0 BCG Fault -2
1 0 1 0 CAB Fault -3
1 1 1 0 ABCG Fault -4
0 0 0 0 No Fault 0
posposzerorlyrly
ZLZLZLIkII /)(**
0
*

3/)___(
0
CIBIAII

*
rly
I
rly
I