Siemens SIPROTEC 7SA522 Manual page 291

Pickup Values,
Delay Time
7SA522 Manual
C53000-G1176-C155-3
The following 3 options are available:
• Stage 2)): The stage is ineffective;
• Stage 21 ZLWK 7ULS: The stage is effective and issues an alarm and a trip
command (after time has expired) following irregular frequency deviations;
• Stage 21 $ODUP RQO\: The stage is effective and issues an alarm but no trip
command following irregular frequency deviations;
The configured pickup value determines whether a frequency element is to respond
to overfrequency or underfrequency.
• If a stage is set to a value above the rated frequency, it is automatically interpreted
to be an overfrequency stage f>.
• If a stage is set to a value below the rated frequency, it is automatically interpreted
to be an underfrequency stage f<.
• If a stage is set exactly to the rated frequency, it is inactive.
A pickup value can be set for each stage according to above rules. The addresses and
possible setting ranges are determined by the rated frequency as configured in the
power system data 1 (Subsection 2.1.3.1) at 5DWHG )UHTXHQF\ (address ).
Please note that none of the frequency stages is set to less than 30 mHz above (for
f>) or below (for f<) of the nominal frequency. Since the frequency stages have a hys-
teresis of approx. 20 mHz, it may otherwise happen that the element does not drop
out when returning to the nominal frequency.
Only those addresses are accessible that match the configured nominal frequency.
For each element, a trip delay time can be set:
• Address  I 3,&.83 pickup value for frequency stage f1 at f
Address  I 3,&.83 pickup value for frequency stage f1 at f
Address  7 I trip delay for frequency stage f1;
• Address  I 3,&.83 pickup value for frequency stage f2 at f
Address  I 3,&.83 pickup value for frequency stage f2 at f
Address  7 I trip delay for frequency element f2;
• Address  I 3,&.83 pickup value for frequency stage f3 at f
Address  I 3,&.83 pickup value for frequency stage f3 at f
Address  7 I trip delay for frequency stage f3;
• Address  I 3,&.83 pickup value for frequency stage f4 at f
Address  I 3,&.83 pickup value for frequency stage f4 at f
Address  7 I trip delay for frequency stage f4;
The set times are additional delay times not including the operating times (measuring
time, drop-out time) of the protective function.
If underfrequency protection is used for load shedding purposes, then the frequency
settings relative to other feeder relays are generally based on the priority of the cus-
tomers served by the protective relay. Normally, it is required for load shedding a fre-
cuency / time grading that takes into account the importance of the consumers or con-
sumer groups.
In interconnected networks, frequency deviations may also be caused by power
swings. Depending on the power swing frequency, the mounting location of the device
and the setting of the frequency stages, it is reasonable to block the entire frequency
protection function or single stages once a power swing has been detected. The delay
times must then be co-ordinated thus that a power swing is detected before the fre-
quency protection trips.
2.16 Frequency protection (optional)
= 50 Hz,
N
= 60 Hz,
N
= 50 Hz,
N
= 60 Hz,
N
= 50 Hz,
N
= 60 Hz,
N
= 50 Hz,
N
= 60 Hz,
N
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