CHARACTERISTICS
59
NV021 - Manual - 08 - 2012
The underfrequency protection is enabled only when the maximum of the input voltages
U
LMAX
=max(
U
L1
,
U
L2
,
U
L3
) overcomes 0.2
U
n
for a
tfEN
adjustable time.
Setting of the
tfEN
value is available inside the
Set \ Base
menu with “level 1” session.
The trip of f< element may be inhibited by the start of the second, third and/or fourth element (
f
<<,
f
<<<,
f
<<<<) by setting
ON
the Disable
f
< by start
f
<<, Disable
f
< by start
f
<<<, Disable
f
< by start
f
<<<< (
f<disbyf<<, f<disbyf<<<, f<disbyf<<<<
) parameters available inside the
Set \ Pro-
fi le A(or B) \ Underfrequency-81U \ f<< Element
(
f<<< Element,f<<<< Element) \ Setpoints
menus.
Similarly the trip of the:
f<< element may be inhibited by start of the third and/or fourth element (
f
<<< and/or
f
<<<<) by setting
ON
the Disable f<< by start f<<<, start f<<<< (
f<<disbyf<<<, f<<disbyf<<<<
) parameter avail-
able inside the
Set \ Profi le A(or B) \ Underfrequency-81U \ f<<< Element, (f<<<< Element) \ Setpoints
menus.
f<<< element may be inhibited by start of the fourth element (
f<<<<
) by setting
ON
the Disable f<<<
by start f<<<< (
f<<<disbyf<<<<
) parameter available inside the
Set \ Profi le A(or B) \ Under-
frequency-81U \ f<<<< Element \ Setpoints
menu.
All the named parameters can be set separately for
Profi le A
and
Profi le B
.
For every of the four thresholds the logic block can be set.
Logical block (Block1)
If the
f<BLK1, f<<BLK1,
f<<<BLK1
and/or
f<<<<BLK1
enabling parameters are set to
ON
and a binary input is designed for logical block (Block1), the protection is blocked off whenever the
given input is active.
The trip timer is held in reset condition, so the operate time counting starts when the input block
goes down.
[1]
The enabling parameters are available inside the
Set \ Profi le A(or B) \ Underfrequency
- 81U \
f< Element
(
f<< Element, f<<< Element, f<<<< Element) \ Setpoints
menus, while the
Block1
function must be assigned to the selected binary input inside the
Set \ Inputs \ Binary input IN1(x)
menus (IN1 or INx matching).
Note 1 The exhaustive treatment of the logical block (Block 1) function may be found in the “Logic Block” paragraph inside
CONTROL AND MONITOR-
ING
section.
•
•
Timers-F81.ai
t
dfEN
81O-81U Enable
81O-81U disabled
81O-81U disabled
81O-81U enabled
0.20
U
n
Max (
U
L1
...
U
L3
)
t
Overfrequency & underfrequency enable timer
Timers-F81.ai
t
dfEN
81O-81U Enable
81O-81U disabled
81O-81U disabled
81O-81U enabled
0.20
U
n
Max (
U
L1
...
U
L3
)
t
Overfrequency & underfrequency enable timer
Fun-F81U_S1.ai
RESET
t
f<def
0
T
TRIP
P
ING
M
A
TRIX
(
L
E
D
+
R
E
L
A
YS
)
f
< Start
f
< Start
f
< Trip
f
< Trip
f
< Trip
BF Enable (ON
≡
Enable)
towards BF logic
&
Block1
f
< BF
&
&
&
Enable (ON
≡
Enable)
Block1 input (ON
≡
Block)
f
< Block1
Block1
Binary input INx
T
0
Logic
INx
t
ON
INx
t
ON
INx
t
OFF
T
0
n.o.
n.c.
INx
t
OFF
t
f<def
f
<ST-K
f
<ST-L
f
<TR-K
f
<TR-L
f<BF
From 2nd, 3rd and/or 4th element
(ON
≡
Inhibit)
f<
inhibition
&
f
≤
f
<
def
f
<
def
f
U
L1...
U
L3
M a x
(
U
L1...
U
L3
) ≥ 2 0 %
U
n
f<BLK1
Logic diagram concerning the first threshold (f<) of the underfrequency element - 81U
