Functions
2.10 Monitoring Functions
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
168
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 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, only the parameter 5307 is relevant.
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 IN lies below the set limit value under address 5303 FUSE FAIL RESID.
In order to detect a 3-phase 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-phase failure is detected. This threshold
value of the current element must be set under address 5307 I> BLOCK. The threshold value should be iden-
tical 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.
Note
The setting under address 5310 BLOCK PROT. has no effect on the flexible protection functions. A separate
blocking can be selected for that purpose.
The function may be disabled in address 5301 FUSE FAIL MON., e.g. when performing asymmetrical tests.
To Next Page
Loading...
Need help?
General
