Technical Data
4.8 Differential Protection (ANSI 87T) for Transformers
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
478
4.8 Differential Protection (ANSI 87T) for Transformers
Setting Ranges / Increments
Trip Time Curves acc. to ANSI
Pickup Times
Differential current I
DIFF
>/I
N Transf
0.05 to 2.00 Increments 0.01
High-current stage I
DIFF
>>/I
N Transf
0.5 to 12.0
or ∞ (ineffective)
Increments 0.1
see also Figure 4-8
Slope 1 0.10 to 0.50 Increments 0.01
Base point 1 I/I
N Transf
0.00 to 2.00 Increments 0.01
Slope 2 0.25 to 0.95 Increments 0.01
Base point 2 I/I
N Transf
0.00 to 10.00 Increments 0.01
Startup recognition I/I
N Transf
0.00 to 2.00 Increments 0.01
Pickup Value Increase on Startup 1.0 to 2.0 Increments 0.1
Max. Startup Time 0.0 to 180.0 s Increments 0.1 s
Add-on stabilization I/I
N Transf
2.00 to 15.00 Increments 0.01
Inrush stabilization I
2fN
/I
fN
(2nd Harmonic)
10 % to 80 %
see also Figure 4-9
Increments 1 %
Stabilization (nth harm.) I
nfN
/I
fN
(n = 3rd or 5th harmonic)
10 % to 80 %
see also Figure 4-10
Increments 1 %
Retract blocking I/I
N Transf
0.5 to 12.0 Increments 0.1
Tripping delay time for I
DIFF
> and I
DIFF
>> 0.00 s to 60.00 s
or ∞ (ineffective)
Increments 0.01 s
Duration of Add-on stabilization (2 to 250) · Cycle duration (Network
frequency)
or ∞ (ineffective)
Time for cross blocking for 2nd, 3rd or 5th har-
monics
(0 to 1000) · Cycle duration (Net-
work frequency)
or ∞ (continuous)
Tripping delay time for I
DIFF
> and I
DIFF
>> 0.00 s to 60 s
or ∞ (ineffective)
Increments 0.01 s
with single side feed (without parallel operation of other protection functions)
Dropout Ratio Approx. 0.7
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