GE Multilin g60 Instruction Manual page 309

5 SETTINGS
The saturation detector is implemented as a state machine (see below). "NORMAL" is the initial state of the machine. When
in "NORMAL" state, the saturation flag is not set (SAT = 0). The algorithm calculates the saturation condition, SC. If SC = 1
while the state machine is "NORMAL", the saturation detector goes into the "EXTERNAL FAULT" state and sets the satura-
tion flag (SAT = 1). The algorithm returns to the "NORMAL" state if the differential current is below the first slope, SL, for
more than 200 ms. When in the "EXTERNAL FAULT" state, the algorithm goes into the "EXTERNAL FAULT & CT SATU-
RATION" state if the differential flag is set (DIF = 1). When in the "EXTERNAL FAULT & CT SATURATION" state, the algo-
rithm keeps the saturation flag set (SAT = 1). The state machine returns to the "EXTERNAL FAULT" state if the differential
flag is reset (DIF = 0) for 100 ms.
(|ID| < SL x IR) or (|ID| < PICKUP)
AND
(NOT (SC)) for 200 ms
PHASE COMPARISON PRINCIPLE:
The test for direction can be summarized by the following equation:
   
If I B or I K I
TS L TS
 
then DIR abs I
= –
TS
else DIR 1
=
where: I = restraining current, DIR = flag indicating that the phase comparison principle is satisfied
R
B = breakpoint 1 setting, I
L
K = factory constant of 0.25
FLEXLOGIC OPERANDS
STATOR DIFF PKP A
STATOR DIFF SAT A
STATOR DIFF DIR A
FLEXLOGIC OPERANDS
STATOR DIFF PKP B
STATOR DIFF SAT B
STATOR DIFF DIR B
FLEXLOGIC OPERANDS
STATOR DIFF PKP C
STATOR DIFF SAT C
STATOR DIFF DIR C
Figure 5–71: STATOR DIFFERENTIAL FINAL OUTPUT LOGIC
GE Multilin
NORMAL
SAT := 0
SC
(saturation condition)
EXTERNAL FAULT
SAT := 1
EXTERNAL FAULT
AND CT SATURATION
SAT := 1
Figure 5–70: SATURATION DETECTION STATE MACHINE
    and
and I 0.1 pu
R TS
  90 
I
NS
, I = current at the terminal and neutral sources, respectively
TS NS
AND
OR
AND
OR
AND
OR
G60 Generator Protection System
SC = (|ID| < SL x IR) and (IR > BL)
where:
IR = restraint current
ID = differential current
DIF = stator differential pickup flag
SL = slope 1 setting
BL = break point 1 setting
PICKUP = pickup setting
DIF = 0
for 100 ms
    
I B or I K I and I
NS L NS R
FLEXLOGIC OPERAND
STATOR DIFF OP A
FLEXLOGIC OPERAND
STATOR DIFF OP B
FLEXLOGIC OPERAND
STATOR DIFF OP C
FLEXLOGIC OPERAND
OR STATOR DIFF OP
842707A1.CDR
5.6 GROUPED ELEMENTS
830736A1.CDR
  
0.1 pu
NS
(EQ 5.7)
5-149
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