Technical Data
4.3 Inverse-Time Overcurrent Protection 51(N)
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
481
4.3
Inverse-Time Overcurrent Protection 51(N)
Operating Modes
Measuring Technique
Setting Ranges / Increments
Trip Time Curves acc. to IEC
Three-phase
Standard
Two-phase
Phases A and C
voltage-independent,
voltage-controlled,
voltage-dependent
All elements
First harmonic, rms value (true rms)
Pickup current 51 (phases)
for
I
Nom
= 1 A 0.10 A to 4.00 A
Increments 0.01 A
for
I
Nom
= 5 A 0.50 A to 20.00 A
Pickup current 51N
(ground)
for
I
Nom
= 1 A 0.05 A to 4.00 A
Increments 0.01 A
for
I
Nom
= 5 A 0.25 A to 20.00 A
Time multiplier T for 51, 51N for IEC curves
0.05 s to 3.20 s or
∞
(disabled)
Increments 0.01 s
Time multiplier T for 51, 51N for ANSI curves
0.50 s to 15.00 s or
∞
(disabled)
Increments 0.01 s
Undervoltage threshold 51V V< for release of 51
10.0 V to 125.0 V
Increments 0.1V
Acc. to IEC 60255-3 or BS 142, Section 3.5.2 (see also Figure 4-1 and 4-2)
The tripping times for
I
/
I
p
≥
20 are identical with those for
I
/
I
p
= 20.
For zero-sequence current read 3
I
0p instead of
I
p
and T
3
I
0p
instead of T
p
;
for ground fault read
I
Ep
instead of
I
p
and T
I
Ep
instead of T
p
Pickup Threshold
approx. 1.10 ·
I
p
www
. ElectricalPartManuals
. com
