Functions
2.11 Monitoring Functions
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
209
2.11.1.8 Setting Notes
Measured Value Monitoring
The sensitivity of measured value monitor can be modified. Default values which are sufficient in most cases
are preset. If especially high operating asymmetries in the currents and/or voltages are to be expected during
operation, or if it becomes apparent during operation that certain monitoring functions activate sporadically,
then the setting should be less sensitive.
Address
8102
BALANCE V-LIMIT
determines the limit voltage (phase-to-phase), above which the voltage
symmetry monitor is effective. Address
8103
BAL. FACTOR V
is the associated symmetry factor; that is, the
slope of the symmetry characteristic curve.
Address
8104
BALANCE I LIMIT
determines the limit current, above which the current symmetry monitor is
effective. Address
8105
BAL. FACTOR I
is the associated symmetry factor; that is, the slope of the symmetry
characteristic curve.
Address
8106
Σ
I THRESHOLD
determines the limit current above which the current sum monitor is activated
(absolute portion, only relative to
I
Nom
). The relative portion (relative to the maximum conductor current) for ac-
tivating the current sum monitor is set at address
8107
Σ
I FACTOR
.
Note
Current sum monitoring can operate properly only when the residual current of the protected line is fed to the
fourth current input (
I
N
) of the relay (see
Power System Data 1
). Furthermore, the fourth current input (
I
N
)
may not be sensitive.
Note
The connections of the ground paths and their adaption factors were set when configuring the general Power
System Data. These settings must be correct for the measured values monitoring to function properly.
Measured value monitoring can be set to
ON
or
OFF
at address
8101
MEASURE. SUPERV
.
Fuse Failure Monitor (FFM)
Via the address
5301
FUSE FAIL MON.
you select under which system conditions the FFM works. Depending
on that, make the required settings in the grounded system via the parameters
5302
,
5303
and
5307
. In a
grounded/isolated system, the parameter
5307
is important.
The settings for the fuse failure monitor must be selected in such manner that reliable activation occurs if a
phase voltage fails, but that false activation does not occur during ground faults in a grounded network. Address
5303
FUSE FAIL RESID
must be set as sensitive as required (with ground faults, below the smallest fault
current).
The FFM picks up if the ground voltage V
N
is higher than the set limit value under address
5302
FUSE FAIL
3Vo
and if the ground current
I
N lies below the set limit value under address
5303
FUSE FAIL RESID
.
In order to detect a three-pole failure, the progress in time of current and voltage is monitored. If the voltage
sinks below the threshold value without a change in the current value, a 3-pole failure is detected. This thresh-
old value of the current element must be set under address
5307
I> BLOCK
. The threshold value should be
identical with the definite time overcurrent protection.
Under address
5310
BLOCK PROT.
it can be determined whether the protection functions should be blocked
upon pickup by the FFM.
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