Windings - GE 845 Instruction Manual

TRANSFORMER
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Windings

6–6
lb Differential 2nd Harmonic (Ib Diff 2nd Harm)
Range: 0.0 to 100.0% in steps of 0.1
lc Differential 2nd Harmonic (Ic Diff 2nd Harm)
Range: 0.0 to 100.0% in steps of 0.1
la Differential 5th Harmonic (Ia Diff 5th Harm)
Range: 0.0 to 100.0% in steps of 0.1
lb Differential 5th Harmonic (Ib Diff 5th Harm)
Range: 0.0 to 100.0% in steps of 0.1
Ic Differential 5th Harmonic (Ic Diff 5th Harm)
Range: 0.0 to 100.0% in steps of 0.1
The values for differential and restraint currents are displayed in per times CT. The CT
primary, from the CT Bank assigned as Signal Input for Winding 1, is the reference CT
(base CT) used for estimating the differential and restraint currents. The winding reference
is explained in the Transformer Setup section.
The phasors of differential and restraint currents are displayed in primary amperes.
The phasors of differential and restraint currents are displayed in primary amperes.
The harmonic derating factor for each of the windings shows the effect of non-sinusoidal
load currents on the power transformer's rated full load current. The actual values
messages display the harmonic derating factor for windings 1 through 3.
The 845 displays winding load parameters as follows:
Path:
Metering > Transformer > Windings
Winding 1 load (W1 Load (% of rated))
Range: 0.0 to 100.0 %
Winding 1 average phase current (W1 Average Ph Current)
Range: 0.000 to 120000.000 A
Winding 1 harmonic derating factor (W1 Harm Derate Factor
Range: 0.00 to 1.00
Winding 2 load (W2 Load (% of rated))
Range: 0.0 to 100.0 %
Winding 2 average phase current (W2 Average Ph Current)
Range: 0.000 to 120000.000 A
Winding 2 harmonic derating factor (W2 Harm Derate Factor)
Range: 0.00 to 1.00
Winding 3 load (W3 Load (% of rated))
Range: 0.0 to 100.0 %
Winding 3 average phase current (W3 Average Ph Current)
Range: 0.000 to 120000.000 A
Winding 3 harmonic derating factor (W3 Harm Derate Factor)
Range: 0.00 to 1.00
For a two winding transformer the winding load and winding average phase current are
calculated as:
W(1/2) Load (% of rated) = √3 x I (1/2) x V (1/2) x 100% / S
avg rated
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: METERING
rated