Now set the current differential parameters as follows:
Setting in GROUP 1 DIFF PROTECTION Value
Trans Diff Enabled
Set Mode Advance
Is1 200.0e-3 PU
K1 20.00%
Is2 1.000 PU
K2 80.00%
tdiff 0 s
Is-CTS 1.500 PU
Is-HS1 10.00 PU
HS2 Status Disabled
Is-HS2 32.00 PU
Zero seq filt HV Disabled
Zero seq filt LV Disabled
Zero seq filt TV Disabled
IH2 Diff Block Enabled
IH2 Diff Set 20%
Cross Blocking Enabled
CT Saturation Enabled
No Gap Enabled
IH5 Diff Block Enabled
IH5 Diff Set 35%
Circuitry Fail Disabled
The differential element does not protect the tertiary winding. Unloaded delta-connected tertiary windings are
often not pr
otected. If protection is required, the delta winding can be earthed at one point through a current
transformer used to provide instantaneous overcurrent protection for the tertiary winding.
5.5 SETTING GUIDELINES FOR SHORT-INTERCONNECTED BIASED DIFFERENTIAL
PR
OTECTION
The P645 can be used to protect busbars. Consider the five feeders - single bus scheme and its differential
pr
otection zone shown below:
Chapter 6 - Transformer Differential Protection P64x
130 P64x-TM-EN-1.3
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