2 Functions
110
7UM61 Manual
C53000-G1176-C127-3
Figure 2-33 Logic diagram of the frequency protection
2.17.2 Setting Notes
General Frequency protection is only effective and available if address 142 FREQUENCY
Prot. is set to Enabled during configuration. If the function is not required
Disabled is set. Address 4201 O/U FREQUENCY serves to switch the function ON or
OFF or to block only the trip command (Block relay).
Pickup Values Configuring the rated frequency of the power system and the frequency threshold for
each of the stages f1 PICKUP to f4 PICKUP in each case the function is established
as either overfrequency or underfrequency protection. If the threshold is configured as
below rated frequency, underfrequency protection is involved. If the threshold is con-
figured as above rated frequency, overfrequency protection is implemented.
Note
If the threshold is set equal to the nominal frequency, the element is inactive.
For the f4 frequency stage, the former applies only if the parameter 4214 THRESHOLD
f4 is set to automatic (default setting). If desired, this parameter can also be set to
f> or f<, in which case the evaluation direction (increase or decrease detection) can
be specified independent of the parametrized f4 PICKUP threshold.
If frequency protection is used for network decoupling and load shedding purposes,
settings depend on the actual network conditions. Normally a graded load shedding is
strived for that takes into account priorities of consumers or consumer groups.
Further application examples are covered under power stations. The frequency values
to be set mainly depend, also in these cases, on power system/power station operator
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