Areva MiCOM P921 - Page 131

Technical Guide P92x/EN FT/E11
User Guide
MiCOM P921-P922-P923 Page 53/110
1
P0400ENa
2 3
FIGURE 3
CONFIGURATION
Menu :
df/dt: CYCLE NB=
3
df/dt: VALIDAT.
NB= 2
PROTECTION
Menu :
(setting of the 1
er
stage)
[81R] df/dt1: =
0.5 Hzs
A
fter the first three instantaneous df/dt values, the first
average value will be calculated (fig.2). This average
value will be compared to the threshold of the df/dt in
the protection menu (1
er
stage in this example):
3
3/2/1/
1/
d
t
d
f
d
t
d
f
d
t
d
f
dtaveragedf
++
=
The second average value will be calculated based
upon the next detected three instantaneous values of
df/dt (fig.3) .This second average value will be
compared to the threshold of the df/dt in the
protection menu (1
er
stage in this example):
3
3/2/1/
2/
d
t
d
f
d
t
d
f
d
t
d
f
dtaveragedf
++
=