Applying The Function Parameter Settings - Siemens siprotec 7SA522 User Manual

Functions
6.2.3.2

Applying the Function Parameter Settings

Grading coordina-
tion chart
6-50
The zones and phases of such a valid fault detection are alarmed, e.g. "Dis. Z1 L1E"
for zone 1 and phase L1 and further processed by the zone logic (refer to Sub-section
6.2.5) and the supplementary functions (e.g. teleprotection logic, section 6.4.1)
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
The function parameters for the polygonal tripping characteristic only apply if during
the configuration of the scope of functions (Section 5.1) the 4XDGULODWHUDO was se-
lected for phase–phase measurement (address ) and/or phase–earth measure-
ment (address ).
It is recommended to initially create a grading coordination chart for the entire galvan-
ically interconnected system. This diagram should reflect the line lengths with their pri-
mary reactance X in Ω/phase. For the reach of the distance zones, the reactance X is
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.
When entering the relay parameters with a personal computer and DIGSI
selected whether the settings are entered as primary or secondary values.
In the case of parameterization with secondary quantities, the values derived from the
grading coordination chart must be converted to the secondary side of the current and
voltage transformers. In general the following applies:
Current transformer ratio
---------------------------------------------------------------------- - Z
Z =
secondary
Voltage transformer ratio
⋅
primary
®
4 it can be
7SA522 Manual
C53000-G1176-C119-2