56
NV021 - Manual - 08 - 2012
CHARACTERISTICS
Overfrequency - 81O
Preface
Two operation thresholds, independently adjustable with adjustable delay are provided.
Each threshold may be separately enabled or disabled.
The fi rst threshold trip may be inhibited by start of the second threshold.
Operation and settings
The frequency, acquired from
U
L1
,
U
L2
,
U
L3
input voltages is compared with the setting values; a start
is issued when the frequency overcomes the adjustable threshold (START); after expiry of the as-
sociated operate time a trip command is issued; if instead the frequency drops below the threshold,
the element it is restored.
When the frequency value is out of the lock range, it is fi xed to the upper or lower limit
(20 Hz or 90 Hz).
Both elements operate with defi nite time characteristic.
Each element can be enabled or disabled by setting
ON
or
OFF
the
State
parameter inside the
Set
\ Profi le A(or B) \ Overfrequency-81O \
f
> Element (or
f
>> Element \ Defi nite time
menu.
The overfrequency 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 fi rst threshold trip (
f
>) may be inhibited by start of the second threshold (
f
>>) by setting
ON
the
f> Disabling by f>> start (
f>disbyf>>
) parameter available inside the
Set \ Profi le A(or B) \ Overfre-
quency-81O \ f>> Element \ Setpoints
menu
Breaker failure (BF)
Both overfrequency elements (
f
>,
f
>>) can produce the Breaker Failure output if the
f>BF
and
f>>BF
parameters are set to
ON.
The parameters are available inside the
Set \ Profi le A(or B) \ Overfrequency - 81O \
f> Element
(
f>>
Element) \ Setpoints
menus.
[1]
Note 1 The common settings concerning the Breaker failure protection are adjustable inside the
Breaker Failure - BF
menu.
—
t-int-F81O.ai
f
t
f
>>
def
f
>
def
t
fdef>>
t
fdef>
General operation time characteristic for the overfrequency elements - 81O
TRIP
t-int-F81O.ai
f
t
f
>>
def
f
>
def
t
fdef>>
t
fdef>
General operation time characteristic for the overfrequency elements - 81O
TRIP
all-F81O.ai
Logic diagram concerning the overfrequency elements - 81O
f
f
ON=inhibit
2nd Pickup Element
1st Pickup Element
Block 1
Block 1
Block 1
B F
&
Block 1
B F
State
f > di s b y f >>
f
>
def
t
f>def
State
f
>>
def
t
f>>def
f > i n h i b i t i o n
f
> Start
f
> Trip
f
>> Start
f
>> Start
f
>> Trip
all-F81O.ai
Logic diagram concerning the overfrequency elements - 81O
f
f
ON=inhibit
2nd Pickup Element
1st Pickup Element
Block 1
Block 1
Block 1
B F
&
Block 1
B F
State
f > di s b y f >>
f
>
def
t
f>def
State
f
>>
def
t
f>>def
f > i n h i b i t i o n
f
> Start
f
> Trip
f
>> Start
f
>> Start
f
>> Trip
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