Siemens 7SJ82, Manual

Page: 560 / 1638

Operating Mode Application and Setting Notes
Counter
The number of directional pulses is the determining operate
criterion. Thus do not set the value for parameter
No. of
pulses for operate
too small. Consider that a permanent
intermittent ground fault will cause many current pulses. If no
time-grading considerations are required, Siemens recommends
using a value in the range of 10 to 20.
Integrator and counter
The integrator and the counter are the determining operate
criteria while the counter criterion is only used for the direction
determination. The value for parameter
No. of pulses for
operate
to fulfill the directional criterion can be set to a rather
small value in the range of 3 to 5.
Parameter:
Sum of extended PU times
•
Default setting
(_:16291:106) Sum of extended PU times
=
20.00 s
This parameter is only relevant in the operating mode
Integrator and counter
.
With the parameter
Sum of extended PU times
, you set the threshold value for the integrator. If the
integration reaches
Sum of extended PU times
, the stage operates if the
Pulse no. reached
signal
and the pickup state is present.
The parameter
Sum of extended PU times
represents one of the 5 selectivity criteria (ground-fault direc-
tion, pickup threshold, pickup extension time, reset time, and integrator threshold value) for coordination of
the relays on subordinate devices. It is comparable to the time grading of the overcurrent protection.
The
Sum of extended PU times
has the shortest summation time in the radial system for the device that
is closest to the intermittent ground fault and that picks up.
Parameter:
Reset time
•
Default setting
(_:16291:107) Reset time
=
300 s
With the parameter
Reset time
, you can define the maximum interval between 2 adjacent ground faults. If
the interval is larger than the
Reset time
, the counter and integrator are reset.
The
Reset time
parameter must be much higher than the operate value of the
Sum of extended PU
times
.
Parameter:
Operate & flt.rec. blocked
•
Default setting
(_:16291:2) Operate & flt.rec. blocked
=
no
With the parameter
Operate & flt.rec. blocked
, you can block the operate indication, the fault
recording, and the fault log. In this case, a ground-fault log is created instead of the fault log.
Settings
Addr. Parameter C Setting Options Default Setting
Stage 1
_:16291:1 Stage 1:Mode
•
off
•
on
•
test
off
_:16291:2 Stage 1:Operate &
flt.rec. blocked
•
no
•
yes
no
_:16291:10 Stage 1:Blk. by meas.-
volt. failure
•
no
•
yes
yes
_:16291:101 Stage 1:Directional
mode
•
forward
•
reverse
forward
6.14.5
Protection and Automation Functions
6.14 Directional Intermittent Ground-Fault Protection
560 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017