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 tfENadjustable 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 \
df> Element (df>> Element, df>>> Element, df>>>> 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 \ df> Element (df>> Element, df>>> Element, df>>>> 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
f
def>>
dt
f
def>>>
dt
f
def>>>>
dt
f
def>
General operation time characteristic for the frequency rate of change elements - 81R
TRIP
Timers-F81R.ai
t
dfEN
81R Enable
81R enabled81R 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
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