Setting Notes - Siemens siprotec SJ62 User Manual

2 Functions

2.3.10 Setting Notes

General
103
The directional overcurrent element providing normal time grading operates as selec-
tive backup protection.
The following figure shows the logic diagram for the generation of fault direction sig-
nals.
Figure 2-29 Logic diagram for the generation of fault direction signals.
When selecting the directional time overcurrent protection in DIGSI, a dialog box
appears with several tabs for setting the associated parameters. Depending on the
functional scope specified during configuration of the protective functions in addresses
115 67/67-TOC and 116 67N/67N-TOC, the number of tabs can vary.
If 67/67-TOC or 67N/67N-TOC = Definite Time is selected, then only the settings
for the definite time elements are available. If TOC IEC or TOC ANSI is selected, the
inverse characteristics are also available. The superimposed directional elements 67-
2 and 67-1 or 67N-2 and 67N-1 apply in all these cases.
At address 1501 FCT 67/67-TOC, directional phase overcurrent protection may be
switched ON or OFF.
Pickup values, time delays, and characteristic are set separately for phase protection
and ground protection. Because of this, relay coordination for ground faults is indepen-
dent of relay coordination for phase faults, and more sensitive settings can often be
applied to directional ground protection. Thus, at address 1601 FCT 67N/67N-TOC,
directional ground time overcurrent protection may be switched ON or OFF indepen-
dent of the directional phase time overcurrent protection.
Depending on the parameter 613 Gnd O/Cprot. w., the device can either operate
using measured values IN or the quantities 3I0 calculated from the three phase cur-
rents. Devices featuring a sensitive ground current input generally use the calculated
quantity 3I0.
The direction determination of the function is affected by parameter 201 CT
Starpoint (see chapter 2.1.3).
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015