Siemens siprotec 7SD5 User Manual

2.18 Frequency Protection (optional)
345
7SD5 Manual
C53000-G1176-C169-1
The following 3 options are available:
•Stage OFF: The stage is ineffective;
•Stage ON: with Trip: The stage is effective and issues an alarm and a trip
command (after time has expired) following irregular frequency deviations;
•Stage ON: Alarm only: The stage is effective and issues an alarm but no trip
command following irregular frequency deviations.
Pickup Values,
Delay Time
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 nominal frequency as configured in the
Power System Data 1 (Section 2.1.2.1) in Rated Frequency (address 230).
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 3602 f1 PICKUP pickup value for frequency stage f1 at f
N
= 50 Hz,
Address 3603 f1 PICKUP pickup value for frequency stage f1 at f
N
= 60 Hz,
Address 3604 T f1 trip delay for frequency stage f1;
•Address 3612 f2 PICKUP pickup value for frequency stage f2 at f
N
= 50 Hz,
Address 3613 f2 PICKUP pickup value for frequency stage f2 at f
N
= 60 Hz,
Address 3614 T f2 trip delay for frequency element f2;
•Address 3622 f3 PICKUP pickup value for frequency stage f3 at f
N
= 50 Hz,
Address 3623 f3 PICKUP pickup value for frequency stage f3 at f
N
= 60 Hz,
Address 3624 T f3 trip delay for frequency stage f3;
•Address 3632 f4 PICKUP pickup value for frequency stage f4 at f
N
= 50 Hz,
Address 3633 f4 PICKUP pickup value for frequency stage f4 at f
N
= 60 Hz,
Address 3634 T f4 trip delay for frequency element f4.
The set times are additional delay times not including the operating times (measuring
time, dropout 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.
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Siemens siprotec 7SD5 Specifications

General

Brand	Siemens
Model	siprotec 7SD5
Category	Relays
Language	English