Inverse Time Element 46-Toc - Siemens siprotec SJ62 User Manual

2 Functions
Settable Dropout
Times
2.7.2

Inverse Time element 46-TOC

Pickup and Trip-
ping
Drop Out for IEC
Curves
Drop Out for ANSI
Curves
147
Pickup stabilization for the definite-time tripping characteristic 46-1, 46-2 can be ac-
complished by means of settable dropout times. This facility is used in power systems
with intermittent faults. Used together with electromechanical relays, it allows different
dropout profiles to be adapted and time grading of digital and electromechanical com-
ponents.
The inverse time element is dependent on the ordered device version. It operates with
IEC or ANSI characteristic tripping curves. The characteristics and associated formu-
las are given in the Technical Data. When programming the inverse time characteristic
46-TOC, also definite time elements 46-2 PICKUP and 46-1 PICKUP are available
(see previous section).
The negative sequence current I2 is compared with setting value 46-TOC PICKUP.
When negative sequence current exceeds 1.1 times the setting value, a pickup annun-
ciation is generated. The tripping time is calculated from the negative sequence
current according to the characteristic selected. After expiration of the time period a
tripping command is output. The characteristic curve is illustrated in the following
Figure.
Figure 2-48 Inverse time characteristic for negative sequence protection
The element drops out when the negative sequence current decreases to approx.
95% of the pickup setting. The time delay resets immediately in anticipation of another
pickup.
When using an ANSI curve, select if dropout after pickup is instantaneous or with disk
emulation. "Instantaneous" means that pickup drops out when the pickup value of
approx. 95 % is undershot. For a new pickup the time delay starts at zero.
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015