Functions
2.9 Frequency Protection 81 (Optional)
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
136
2.9.2 Setting Notes
General
Frequency protection is only in effect and accessible if address 136 81 O/U is set to Enabled during config-
uration of protective functions. If the function is not required, set Disabled.
The frequency protection function features 4 frequency elements f1 to f4 each of which can function as over-
frequency element or underfrequency element. Each zone can be set active or inactive. This is set in address-
es:
• 3601 81 O/U FREQ. f1 for frequency element f1,
• 3611 81 O/U FREQ. f2 for frequency element f2,
• 3621 81 O/U FREQ. f3 for frequency element f3,
• 3631 81 O/U FREQ. f4 for frequency element f4,
The following 3 options are available:
• Element OFF: The element is ineffective;
• Element ON: with Trip: The element is effective and issues an alarm and a trip command (after time has
expired) following irregular frequency deviations;
• Element ON: Alarm only: The element is effective and issues an alarm but no trip command following
irregular frequency deviations;
Pickup Values, Time Delay
The configured pickup value determines whether a frequency element is to respond to overfrequency or under-
frequency.
• If an element is set to a value above
the rated frequency, it is automatically interpreted to be an overfrequen-
cy element f>.
• If an element is set to a value below
the rated frequency, it is automatically interpreted to be an underfre-
quency element f<.
• If an element is set exactly to the rated frequency
, it is inactive.
A pickup value can be set for each element 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 Rated Frequency (address 230).
Please note that none of the frequency elements is set to less than 30 MHz above (for f>) or below (for f<) of
the nominal frequency. Since the frequency elements have a hysteresis 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
time delay can be set:
• Address 3602 81-1 PICKUP pickup value for frequency element f1 at f
N
= 50 Hz,
Address 3603 81-1 PICKUP pickup value for frequency element f1 at f
N
= 60 Hz,
Address 3604 81-1 DELAY trip delay for frequency element f1;
• Address 3612 81-2 PICKUP pickup value for frequency element f2 at f
N
= 50 Hz,
Address 3613 81-2 PICKUP pickup value for frequency element f2 at f
N
= 60 Hz,
Address 3614 81-2 DELAY trip delay for frequency element f2;
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