Inverse-Time Overcurrent Protection - Siemens 7SK80 Manual

Technical Data

4.3 Inverse-time Overcurrent Protection

4.3 Inverse-time Overcurrent Protection
Modes of Operation
Three-phase
Two-phase
voltage-independent,
voltage-controlled,
voltage-dependent
Measuring Technique
All elements
Setting Ranges / Increments
Pickup currents 51 (phases)
Pickup currents 51N
(ground)
Time multiplier T for 51, 51N
for IEC characteristics
Time multiplier T for 51, 51N
for ANSI characteristics
Undervoltage threshold 51V V< for release of 51 10.0 V to 125.0 V
Trip Time Curves acc. to IEC
Acc. to IEC 60255-3 or BS 142, Section 3.5.2 (see also Figures 4-1 and 4-2)
The tripping times for I/I
For zero sequence current, read 3I0p instead of I
for ground fault, read I
Pickup threshold
362
Standard
Phases A and C
First harmonic, rms value (true rms)
for I = 1 A 0.10 A to 4.00 A
Nom
for I = 5 A 0.50 A to 20.00 A
Nom
for I = 1 A 0.05 A to 4.00 A
Nom
for I = 5 A 0.25 A to 20.00 A
Nom
≥ 20 are identical with those for I/I
p
instead of I and T instead of T
Ep p IEp
0.05 s to 3.20 s or ∞
(disabled)
0.50 s to 15.00 s or ∞
(disabled)
= 20
p
and T instead of T ;
p 3I0p p
p
approx. 1.10 · I
p
E50417-G1140-C344-A5, Release date 11.2012
Increments
0.01 A
Increments
0.01 A
Increments 0.01
s
Increments 0.01
s
Increments 0.1 V
SIPROTEC, 7SK80, Manual