Applying The Function Parameter Settings - Siemens siprotec 7SA6 User Manual

6.2.4.2

Applying the Function Parameter Settings

Grading
Coordination Chart
7SA6 Manual
C53000-G1176-C133-1
Dis switched off
Dis blocked
PS blocking
Dis FD forward
Dis FD reverse
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Figure 6-33 Release logic for a zone (example for Z1)
In total the following zones are available:
Independent zones:
• 1st zone (fast tripping zone) Z1 with 5 = , ; = ; may be delayed by 7
SKDVH and 7PXOWLSKDVH
• 2nd zone (back up zone) Z2 with 5 = , ; = ; may be delayed by 7SKDVH
and 7PXOWLSKDVH
• 3rd zone (back up zone) Z3 with 5 = , ; = ; may be delayed by 7 '(/$<
• 4th zone (back up zone) Z4 with 5 = , ; = ; may be delayed by 7 '(/$<
• 5th zone (back up zone) Z5 with 5 = , ; =  (forward) and X (Z5)-
(reverse); may be delayed by 7 '(/$<
Dependent (controlled) zone:
• Overreaching zone Z1B with 5 =% , ; =% ; may be delayed by 7%SKDVH
and 7%PXOWLSKDVH
It is recommended to initially create a grading coordination chart for the entire
galvanically interconnected system. This diagram should reflect the line lengths with
their primary reactance X in Ω/phase. For the reach of the distance zones, the
reactances X are the deciding quantities.
The first zone Z1 is usually set to cover 85 % of the protected line without any trip time
delay (i.e. T1 = 0.00 s). The protection clears faults in this range without additional
time delay, i.e. the tripping time is the relay basic operating time.
The tripping time of the higher zones is sequentially increased by one time grading
margin. The grading margin must take into account the circuit breaker operating time
including the spread of this time, the resetting time of the protection equipment as well
as the spread of the protection delay timers. Typical values are 0.2 s to 0.4 s. The
reach is selected to cover up to approximately 80 % of the zone with the same set time
delay on the shortest neighbouring feeder.
≥1
&
≥1
&
&
further
zones
Functions
&
release of Z1
6-59