GE t60 Instruction Manual page 250

8.2 DIFFERENTIAL CHARACTERISTIC TEST EXAMPLES
d) SLOPE 1 TEST
Inject current in such a manner that the magnitude of I
intersection of the minimum PKP and Slope 1 and smaller than the Breakpoint 1 setting; that is,
1. Change the current magnitudes as follows:
WINDING 1
PHASE SINGLE CURRENT (I
0 A ∠0°
A
0.48 A ∠0°
B
0.48 A ∠–180°
C
2. The following differential and restraint current should be read from the T60 actual values menu:
PHASE DIFFERENTIAL CURRENT (I
0 ∠0°
A
0.113 pu ∠0°
B
0.113 pu ∠0°
C
The Percent Differential element will not operate even though I
is not large enough to make the
NOTE
3. Adjust the I current as shown below (thereby increasing I
1
WINDING 1
PHASE SINGLE CURRENT (I
0 A ∠0°
A
0.45 A ∠0°
B
0.45 A ∠–180°
C
4. The following differential and restraint current should appear in the T60 actual values menu:
PHASE DIFFERENTIAL CURRENT (I
0 ∠0°
A
0.170 pu ∠0°
B
0.170 pu ∠0°
C
⁄
5. The actual I I ratio is now 17%. Verify that the element operates correctly.
d r
8
8-6
(
I intersection of Min PKP and Slope 1
r
WINDING 2
) PHASE SINGLE CURRENT (I
1
0 A ∠0°
A
1 A ∠–180°
B
1 A ∠0°
C
) PHASE
d
A
B
C
⁄
I I ratio larger than the Slope 1 setting of 15%. The actual ratio is 11.3%.
d r
WINDING 2
) PHASE SINGLE CURRENT (I
1
0 A ∠0°
A
1 A ∠–180°
B
1 A ∠0°
C
) PHASE
d
A
B
C
T60 Transformer Management Relay
is larger than the restraint current of 0.67 pu, corresponding to the
r
) < ( ) I < (
I actual Break 1
r r
)
2
RESTRAINT CURRENT (I )
r
0 ∠0°
1 pu ∠–180°
1 pu ∠0°
is larger than the Minimum Pickup, because I
d
) and verify that the element operates.
d
)
2
RESTRAINT CURRENT (I )
r
0 ∠0°
1 pu ∠–180°
1 pu ∠0°
8 COMMISSIONING
)
(EQ 8.9)
GE Multilin
d