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308
FUNCTION CHARACTERISTICS
—
Frequency rate change - 81R
Preface
The protection is available in the XMR-V, XMR-P and XMR-T versions.
Fast trips may be issued when positive/negative or any (module) changes in frequency are detected.
The 81R element is faster than underfrequency and overfrequency protections.
Four operation thresholds, independently adjustable with adjustable delay are provided.
Each threshold may be separately enabled or disabled.
Operation and settings
The frequency rate of change, acquired from
U
L1
input voltage, is compared with the setting values;
a start is issued when the frequency overcomes the adjustable threshold (START); after expiry of
the associated operate time a trip command is issued; if instead the frequency rate of change drops
below the threshold, the element is restored.
When the frequency value is out of the lock range, it is fixed to the upper or lower limit (20 Hz or 90 Hz).
All elements operate with definite time characteristic.
The frequency rate of change protection is enabled only when the maximum of the
U
L1
input voltage
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.
Each element can be enabled or disabled by setting
ON
or
OFF
the
Sta
-
te
parameter inside the
Set \ Profile A (or B) \ Frequency rate of change-81R \
d
f
> Element (d
f
>> Element, d
f
>>> Element, d
f
>>>> Element) \ Definite time
menu.
For every threshold the positive/negative or module of frequency change cam be selected (typically
for speedup/slowdown or any speed change of the generator; the df operating mode can be set
(
Mode-df>, Mode-df>>, Mode-df>>>, Mode-df>>>>
) inside the
Set \ Profile A (or B) \ Fre-
quency rate of change-81R \ d
f
> Element (d
f
>> Element, d
f
>>> Element, d
f
>>>> Element) \ Setpoints
menu.
The trip of df> element may be inhibited by the start of the second, third and/or fourth ele-
ment (
df
>>,
df
>>>,
df
>>>>) by setting
ON
the Disable
df
> by start
df
>>, Disable
df
> by
start
df
>>>, Disable
df
> by start
df
>>>> (
df>disbydf>>, df>disbydf>>>, df>disby-
df>>>>
) parameters available inside the
Set \ Profile A (or B) \ Frequency rate of change-81R
\ df>> Element
(
df>>> Element, df>>>> Element) \ Setpoints
menus.
Similarly the trip of the:
• df>> element may be inhibited by start of the third and/or fourth element (
df
>>> and/or
df
>>>>)
by setting
ON
the Disable df>> by start df>>>, start df>>>> (
df>>disbydf>>>, df>>disby-
df>>>>
) parameter available inside the
Set \ Profile A (or B) \ Frequency rate of change-81R
\ df>>> Element, (df>>>> Element) \ Setpoints
menus.
• df>>> element may be inhibited by start of the fourth element (
df>>>>
) by setting
ON
the Disable
df>>> by start df>>>> (
df>>>disbydf>>>>
) parameter available inside the
Set \ Profile A (or B)
\ Frequency rate of change-81R \ df>>>> Element \ Setpoints
menu.
• All the named parameters can be set separately for
Profile A
and
Profile B
.
df
t
df
>>>>
def
df
>>>
def
df
>>
def
df
>
def
dt
fdef>>
dt
fdef>>>
dt
fdef>>>>
dt
fdef>
General operation time characteristic for the frequency rate of change elements - 81R
TRIP
Timers-F81R.ai
t
dfEN
81R Enable
81R enabled
81R disabled
81R disabled
0.20
U
n
U
L1
t
Frequency rate of change enable timer - 81R
XMR-D EQUIPMENT MANUAL
Ed. 2.9 - 02/2021