Inverse Time Element (46-Toc) - Siemens SIPROTEC 7SJ62 Instruction Manual

6.7.1.3

Inverse Time Element (46-TOC)

Pickup and
Tripping
Drop Out for IEC
Curves
Drop Out for ANSI
Curves
7SJ62 Manual
C53000-G1140-C121-1
t
T I >
2
46-1
T I >>
2
46-2
Figure 6-40 Definite Time Characteristic for Negative Sequence Protection
The inverse time element is designated 46-TOC and can operate with IEC or ANSI
characteristic tripping curves depending on the model ordered. The curves and asso-
ciated formulas are given in the Technical Specifications (Figures 10-4 and 10-5 in
Section 10.8). When programming the inverse time curve, the definite time elements
are available (see Subsection 6.7.1.2).
When the negative sequence current exceeds the pickup setting of the 46-TOC ele-
ment by 110%, the element picks up, generates a message, and initiates time delayed
tripping based on the selected characteristic curve. Once the corresponding time in-
terval on the curve elapses, a tripping signal is initiated. The characteristic curve is il-
lustrated in Figure 6-41.
When IEC curves are used, the 46-TOC element drops out when the negative se-
quence current decreases to 95 % of the pickup setting. The time delay resets imme-
diately in anticipation of another pickup.
When ANSI curves are used, the 46-TOC element may drop out immediately when
the negative sequence current decreases to 95 % of the pickup setting, or disk emu-
lation may be used to simulate the unwinding of an electromechanical induction disc.
If disk emulation is selected, the drop out begins when the current decreases to 90 %
of the pickup value, and reset proceeds in accordance with the selected reset curve.
When the negative sequence current is between 90 % and 95 % of the pickup setting,
neither forward nor reverse movement of the disk is simulated. When the negative se-
quence current falls below 5 % of the pickup value, disk emulation is terminated and
immediate reset takes place. Figure 6-41 illustrates the overall tripping characteristic.
Tripping Area
Auslösebereich
I > I >>
46-1
46-2
2 2
Functions
I
2
6-87