Test Example 2 - GE T60 Instruction Manual
Transformer protection system
Hide thumbs
Also See for T60:
- Instruction manual (796 pages) ,
- Communications manual (532 pages) ,
- Instruction manual (628 pages)
Table of Contents
Advertisement
CHAPTER 8: COMMISSIONING
4.
Read the following differential and restraint current values in the T60 actual values menu.
Phase
Differential current (I
0 ∠0°
A
8.631 pu ∠–180°
B
8.631 pu ∠0°
C
5.
The actual I
/I
ratio is now 95.9%. Verify that the element operates correctly.
d
r
8.2.2.7 Summary
The tests described the principles of testing the differential element for all regions from the operating characteristic.
For verification of more points, consider adjusting the magnitude of the restraint current I
characteristic and change the other current to vary I
and expected operating values.
A blank result table is provided at the end of this chapter for convenience.
8.2.3 Test example 2
8.2.3.1 D/yg30° transformer with phase A to ground fault on the grounded Wye
Transformer data — D/y30°, 20 MVA, 115/12.47 kv, CT1 (200:1), CT2 (1000:1)
Figure 8-3: Current distribution of a D/yg30° transformer with an LV-side ground fault
Test
Phase
Injected current
W1 current
Balanced
A
0.29 ∠0°
Condition
B
0 ∠0°
C
0.29 ∠–180°
Minimum
A
0.137 ∠0°
Pickup
B
0 ∠0°
C
0.137 ∠–180°
Minimum
A
0.108 ∠0°
Pickup
B
0 ∠0°
C
0.108 ∠–180°
T60 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
)
Phase
Restraint current (I
d
0 ∠0°
A
9 pu ∠–180°
B
9 pu ∠0°
C
until the relay operates. Use the Excel tool to compare the actual
d
Displayed current
W2 current
Differential
0.926 ∠–180°
0 ∠0°
0 ∠0°
0 ∠0°
0 ∠0°
0 ∠0°
0.521 ∠–180°
0.048 ∠0°
0 ∠0°
0 ∠0°
0 ∠0°
0.048 ∠0°
0.521 ∠–180°
0.102 ∠0°
0 ∠0°
0 ∠0°
0 ∠0°
0.102 ∠0°
DIFFERENTIAL CHARACTERISTIC TEST EXAMPLES
)
r
to the required portion of the
r
Status
Restraint
0.5349 ∠–180°
Not Applicable
0 ∠0°
0.5349 ∠0°
0.3 ∠–180°
Block
I
= 0.048 < Min PKP
d
0 ∠0°
0.3 ∠0°
0.3 ∠–180°
Operate
I
= 0.102 > Min PKP
d
0 ∠0°
0.3 ∠0°
8
8-9
- Quick Links:
- Introduction
Hide quick links:
Advertisement
Table of Contents
