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1MAC050144-MB C
Section 4
Protection functions
615 series ANSI
353
Technical Manual
Figure 170:
Differential protection of a generator-transformer block and short
cable/line
87T can also be used in three-winding transformer applications or two-winding
transformer applications with two output feeders.
On the double-feeder side of the power transformer, the current of the two CTs per phase
must be summed by connecting the two CTs of each phase in parallel. Generally this
requires the interposing CTs to handle the vector group and/or ratio mismatch between the
two windings/feeders.
The accuracy limit factor for the interposing CT must fulfill the same requirements as the
main CTs. Please note that the interposing CT imposes an additional burden to the main
CTs.
The most important rule in these applications is that at least 75 percent of the short-circuit
power has to be fed on the side of the power transformer with only one connection to the
IED.
Summary of Contents for 615 Series ANSI
Page 1: ...Relion Protection and Control 615 series ANSI Technical Manual ...
Page 2: ......
Page 29: ...1MAC050144 MB C Section 615 series ANSI 22 Technical Manual ...
Page 389: ...Section 4 1MAC050144 MB C Protection functions 382 615 series ANSI Technical Manual ...
Page 485: ...Section 6 1MAC050144 MB C Supervision functions 478 615 series ANSI Technical Manual ...
Page 635: ...Section 10 1MAC050144 MB C Other functions 628 615 series ANSI Technical Manual ...
Page 711: ...Section 16 1MAC050144 MB C Glossary 704 615 series ANSI Technical Manual ...
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