Ormazabal ekor.rps, Общее руководство по инструкции, Страница: 88 / 144

IG-150-EN version 04; 03/10/16
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Protection functions. Description and settings General instructions
ekor.rps
4.18.1. Minimum frequency
Each step picks up if the frequency is below the set value
during a number of cycles equal or higher than the setting
“Nr. of pickup cycles”. Once it picks up, the programmed
time must elapse to produce trip. The unit drops out if
during two cycles the frequency is correct.
Lockings
If the voltage in phase B is lower than the setting “Minimum
supervision voltage”, the frequency units pickup is not
allowed.
4.18.2. Maximum frequency
This unit causes pick up if the frequency is above the set
value during a number of cycles equal or higher than
the setting “Nr. of pickup cycles”. Once it picks up the
programmed time must elapse to produce trip. The unit
drops out if during two cycles the frequency is correct.
A trip by this function does not cause recloser actuation.
Lockings
If the voltage in phase B is lower than the setting “Minimum
supervision voltage” the frequency units pickup is not
allowed.
4.18.3. Frequency gradient
General description
This function has 4 steps. In each step, a relay activation
occurs, if the frequency variation per time unit (frequency
decreasing) is higher than the set value.
The function is only effective for frequencies lower than a
threshold called “maximum supervision frequency”, and for
currents higher than a threshold called “Minimum current”.
4.18.3.2.Settings (6 tables)
Setting Min Max Step Notes
Enable. df/dt.
YES/NO (for all steps)
Max. frequency supervision [Hz]
40 70 0.01 (for each step)
Supervision minimum current [A] 0 100.0 0.1 (for all steps)
Pickup value (df/dt) [Hz/s]
0.20 5 0.05 (for each step)
Definite time [s]
0 2 0.01 (for each step)
Nº of pickup cycles D81 3 15 1 (for all steps)
Table 4.25.
Settings
In the console, the settings corresponding to each step
are in the square “FREQUENCY DERIVATIVE” on the screen
“frequency protection (1)”. The common settings, minimum
voltage and Nr. of pickup cycles D81 (for the frequency
derivative) are in the square “FREQUENCY SUPERVISION”.
The frequency measurement of each cycle is executed
refreshing it each half cycle, as the figure shows.
The algorithm is executed each 5 ms only if the phase B
voltage has crossed zero.
Both positive and negative crosses are measured but the
frequency measurement is executed in complete cycles.
The frequency is measured up to 35 Hz. Below this value,
the frequency units are not activated.
Figure 4.21.
frequency measurement