Loss Of Excitation - GE G30 Instruction Manual

9 APPLICATION OF SETTINGS
The minimum operate time of stage 1 will be set to 0.25 seconds, the maximum operating time will be 10 minutes, and the
reset time will be set to 4 minutes.
Stage 2 is typically set lower than stage 1 with a time delay to prevent nuisance alarms for external faults that are normally
cleared by system protection. For the application example, the pickup setting is:
Source 2 will be chosen for this element. The settings are as follows:
For the example system, we have the following values:
Z
( )
b sec
CENTER 1
CENTER 2
The voltage supervision setting will be determined by a system study and may be disabled on either element if required. VT
fuse failure should supervise this element.
GE Multilin
Pickup 70% I × capability
=
2
2
base kV CT ratio
-------------------------- - × -------------------- - ----------------------------------- -
= =
base MVA VT ratio 211.765 MVA
X '(sec) X ' Z × (sec) 0.216 15.54 Ω
= =
d d b
( ) × ( )
X sec X Z sec 1.967
= =
d d b
( ) '(sec)
Z sec X
+
b d
------------------------------------------------ -
=
2
Z ( sec )
b
--------------------
RADIUS 1
= =
2
PICKUP DELAY 1
( ) '(sec)
X sec X
+
d d
-------------------------------------------------
=
2
( )
X sec
d
RADIUS 2 -------------------- -
= =
2
G30 Generator Protection System
0.70 × 8% 5.6%
= =
2
( 18 kV ) 1600
× -------------- - 15.54 Ω
=
157.5
× 3.36 Ω
=
× 15.54 Ω 30.57 Ω
=
15.54Ω 3.36Ω
+
------------------------------------------ - 9.45 Ω
= =
2
15.54 Ω
--------------------- - 7.77 Ω
=
2
0.06 seconds
=
30.57Ω 3.36Ω
+
------------------------------------------ - 16.97 Ω
= =
2
30.57 Ω
--------------------- - 15.28 Ω
=
2
9.1 SETTING EXAMPLE
(EQ 9.6)

9.1.6 LOSS OF EXCITATION

(EQ 9.7)
(EQ 9.8)
(EQ 9.9)
(EQ 9.10)
(EQ 9.11)
(EQ 9.12)
(EQ 9.13)
(EQ 9.14)
9-7
9