GE M60, Instruction Manual

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5-228 M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
GROUPED ELEMENTS CHAPTER 5: SETTINGS
5
Figure 5-125: Saturation detection state machine
5.7.4.2 Phase comparison principle
The test for direction can be summarized by the following equation:
If (|I
TS
| > B
L
or (|I
TS
| > K x I
R
and |I
TS
| > 0.1 pu)) and (|I
NS
| > B
L
or (|I
NS
| > K x I
R
and |I
NS
| > 0.1 pu))
then DIR = abs (
∠
I
TS
-
∠
I
NS
) > 90°
else DIR = 1 Eq. 5-27
where
I
R
= restraining current
DIR = flag indicating that the phase comparison principle is satisfied
B
L
= breakpoint 1 setting
I
TS
, I
NS
= current at the terminal and neutral sources, respectively
K = factory constant of 0.25
Figure 5-126: Stator differential final output logic