EMR-5000
IM02602012E
Frequency Functions
Due to its various frequency functions, the device is very flexible. That makes it suitable for a wide range of
applications where frequency supervision is an important criterion.
In the
Device Planning menu, the User can decide how to use each of the six frequency elements.
f[1] to f[6] can be assigned as:
•
81U – Underfrequency;
•
81O – Overfrequency;
•
81R – Rate of Change of Frequency (df/dt);
•
81UR – Underfrequency and Rate of Change of Frequency (df/dt);
•
81OR – Overfrequency and Rate of Change of Frequency (df/dt);
•
81U
Δ
R – Underfrequency and DF/DT (absolute frequency change per definite time interval);
•
81O
Δ
R – Overfrequency and DF/DT (absolute frequency change per definite time interval); and
•
78V – Vector Surge.
81U – Underfrequency
This protection element provides a pickup threshold and a tripping delay. If the frequency falls below the set pickup
threshold, an alarm will be issued instantaneously. If the frequency remains under the set pickup threshold until the
tripping delay has elapsed, a tripping command will be issued.
With this setting, the frequency element protects electrical generators, loads, or electrical operating equipment in
general against underfrequency.
81O – Overfrequency
This protection element provides a pickup threshold and a tripping delay. If the frequency exceeds the set pickup
threshold, an alarm will be issued instantaneously. If the frequency remains above the set pickup threshold until the
tripping delay has elapsed, a tripping command will be issued.
With this setting, the frequency element protects electrical generators, loads, or electrical operating equipment in
general against overfrequency.
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