Backup Distance - GE G60 Instruction Manual

9.1 SETTING EXAMPLE
where A = 28.2, B = 0.1217, and p = 2. Solving for TDM, we have:
Since this element will coordinate with system protections a timed reset is chosen. The element must be blocked for a VT
fuse failure. The neutral source will be chosen. Make the following changes in EnerVista UR Setup or through the
!"
GROUPED ELEMENTS
This function provides time-delayed protection for system faults that have not been cleared by system protections and to
provide backup protection for stator faults.
The "Line" source will be used in this example to permit the application of a forward and reverse zone. The memory dura-
tion will be left at the default setting ("10 cycles").
Zone 1 will look forward and cover the GSU and the transmission line leaving the station. Zone 3 will look in the reverse
direction and cover the stator winding. Zone 2 will not be used in this example. A mho shape will be chosen for both ele-
ments. Both the VTs and the CTs are located on the low voltage side of the GSU. The transformer vector diagram shows
this transformer to be Dy1 (referenced from the LV side). Consequently Dy1 is chosen form both the
setting and the
XFMR CUR CONNECTION
sen for both of the Zone 3 transformer connection settings. The reach of the Zone 1 element will be set at 120% of imped-
ance of the GSU and the transmission line. In the instance that there are multiple lines and/or multiple generators, the Zone
1 reach must be increased to compensate for the infeed effect.
Transformer Impedance
9
Line Impedance
Zone 1 Reach
9-6
×
-------------------------------------------------------------------------------------- -
T TDM
=

-------------------------------------------------------------------- -

×
I Pickup Reduction
pickup
TDM ---------------------------------------------------------------------------
=
28.2
----------------------------------------------------- -
2.64

----------------------------------- -

×
1.275 0.329
!" !"
SETTING GROUP 1 PHASE CURRENT
setting. There are no transformers in the reverse direction. Therefore "None" is cho-
2
V
L
⋅
X ---------------
=
T
MVA
2
V
L
⋅ (
X ------ - 15 j75
= = +
L
2
V
H
⋅ (
1.2 Transformer Impedance
=
⋅ (
1.2 j0.162 0.255 j1.276
= + +
G60 Generator Management Relay
A
B
+
p
I

1
–

0.75
0.88
=
0.217
+
2

1
–

! menu:
PHASE TOC1
2
( )
18
⋅
j0.1 ------------- - j0.162 primary ohms
= =
100
T
2
( )
18
) ⋅
---------------- - 0.255 j1.276 primary ohms
= +
2
( )
138
CT Ratio
) ⋅ ---------------------- -
Line Impedance
+
VT Ratio
1600
) ⋅ -------------- - ∠
17.8 80° secondary ohms
=
157.5
9 APPLICATION OF SETTINGS
(EQ 9.19)
(EQ 9.20)
SETTINGS

9.1.10 BACKUP DISTANCE

XFMR VOL CONNECTION
(EQ 9.21)
(EQ 9.22)
(EQ 9.23)
GE Multilin