Table of Contents
Advertisement
Functions
f4
f3
f2
f1
OFF
ON
"1"
4505 df1/dt & f1
5232
f1 picked up
-df/dt<
+df/dt>
"1"
4502 df1/dt >/<
4503 STAGE df1/dt
df/dt
df/dt≤
f≤fn
df/dt
df/dt≥
f≥fn
5504
>df1/dt block
5503
>df/dt block
4518 U MIN
U1
U1≤
Figure 2-78 Logic Diagram of the Rate-of-Frequency-Change Protection
2.24.2 Setting Hints
General
Pickup Values
168
OR
&
&
OR
&
OR
The rate-of-frequency-change protection is only effective and accessible if during the
configuration address 145 df/dt Protect. has been set accordingly. 2 or 4 stages
can be selected. The default setting is 2 df/dt stages.
Address 4501 df/dt Protect. allows to switch the function ON or OFF, or to block
only the trip command (Block relay).
The setting procedure is the same for all stages. In a first step, it must be determined
whether the stage is to monitor a frequency rise at f>f
For stage 1, for instance, this setting is made at address 4502 df1/dt >/<. The pick-
up value is set as an absolute value at address 4503 STAGE df1/dt. The setting of
address 4502 informs the protection function of the applicable sign.
The pickup value depends on the application and is determined by power system con-
ditions. In most cases, a network analysis will be necessary. A sudden disconnection
of loads leads to a surplus of active power. The frequency rises and causes a positive
frequency change. A failure of generators, on the other hand, leads to a deficit of ac-
tive power. The frequency drops and leads to a negative frequency change.
4504 T df1/dt
&
5512
df/dt BLOCKED
5514
df/dt U< block
5516
df1/dt pickup
5517
df2/dt pickup
5518
df3/dt pickup
5519
df4/dt pickup
5520
df1/dt TRIP
5521
df2/dt TRIP
5522
df3/dt TRIP
5523
df4/dt TRIP
Tripping
matrix
Tmin TRIP
CMD
or a frequency drop at f< f
N
7UM62 Manual
C53000-G1176-C149-3
.
N
Advertisement
Table of Contents
