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Section 4
1MAC050144-MB C
Protection functions
354
615 series ANSI
Technical Manual
Figure 171:
Differential protection of a three-winding transformer and a transformer
with two output feeders
Transforming ratio correction of CTs
First, the rated load of the power transformer must be calculated on both sides when the
apparent power and phase-to-phase voltage are known.
(Equation 42)
I
nT
rated load of the power transformer
S
n
rated power of the power transformer
V
n
rated phase-to-phase voltage
Next, the settings for the CT ratio correction can be calculated.
(Equation43)
After the CT ratio correction, the measured currents and corresponding setting values of
87T are expressed in multiples of the rated power transformer current Ir (xIn) or
percentage value of Ir (%Ir).
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 ...
Page 712: ......