Figure. 5.3.14 - 139. Simplified function block diagram of the f< function.
Measured input
The frequency protection function compares the measured frequency to the pick-up setting (given in
Hz). The source of the measured frequency depends on the user-defined tracking reference which can
be chosen from the
Frequency tab of the Measurement menu.
Table. 5.3.14 - 130. Measurement inputs of the f>/< function.
Signals
Description
Time base
VT1 U1, U2, U3
L-N voltages of the first voltage transformer
5ms
VT2 U1, U2, U3
L-N voltages of the second voltage transformer
5ms
Pick-up and time delay
The
f
set
>, f
set
>>, etc.setting parameters control the pick-up of each stage of the f>/< function.
They define the maximum or minimum allowed measured frequency before action from the function.
The function constantly calculates the ratio between the pick-up setting and the measured frequency.
The reset ratio of 20mHz is built into the function and is always relative to the pick-up value.
Table. 5.3.14 - 131. Pick-up settings.
Name
Description
Range
Step
Default
f> used in setting group
f>> used in setting group
f>>> used in setting
group
f>>>> used in setting
group
f< used in setting group
f<< used in setting group
f<<< used in setting
group
f<<<< used in setting
group
Enables or disables the protection stage in the setting
group.
0: No
1: Yes
-
0: No
fset>
fset>>
fset>>>
fset>>>>
Pick-up setting
10.00…80.00Hz
0.01Hz 51Hz
A
AQ
Q-M215
-M215
Instruction manual
Version: 2.04
194