Siemens 7SJ82 - Page 559

With the parameter Pickup mode, you define under which conditions pickup is detected and fault logging
and recording start:
•
When the parameter Pickup mode is set to with 3I0>, the signal Pickup is released without consid-
ering the ground fault direction. The signal
Pickup is issued once the IN/3I0 exceeds the threshold
value.
•
When the parameter Pickup mode is set to with direction, the signal Pickup is issued when at
least one pulse direction is the same as the direction specified by the set value of parameter Direc-
tional mode.
Parameter: Operating mode
•
Default setting (_:16291:103) Operating mode = Counter
With the parameter Operating mode, you define if the function operates in Counter or in Integrator
and counter mode.
Operating Mode Application and Setting Notes
Counter
The number of directional pulses is the determining operate criterion. This
is a simple method which is similar to the implementation in the 7SJ
SIPROTEC 4 devices. Siemens recommends using this method if no time
grading or only simple time grading between protection devices (time
grading of only 2 or 3 devices) is required.
Time grading is then carried out by increasing the parameter value No.
of pulses for operate towards the infeed.
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 inte-
grator works in the same way as for the non-directional intermittent
ground fault function. This allows the same time-grading principles as for
the non-directional intermittent ground fault function. Refer to this func-
tion for more description.
Parameter: No.of pulses for interm.GF
•
Default setting (_:16291:104) No.of pulses for interm.GF = 3
With the parameter No.of pulses for interm.GF, you set the total number of pulse counts (forward,
reverse and non-dir. pulses) at which the ground fault is considered to be intermittent. Siemens
recommends using the default setting.
Parameter: Pickup extension time
•
Default setting (_:16291:105) Pickup extension time = 0.10 s
With the parameter Pickup extension time, you get a prolonged and thus stabilized pickup signal. This
stabilization is especially important for the coordination with existing static or electromechanical overcurrent
protections.
Parameter: No. of pulses for operate
•
Default setting (_:16291:108) No. of pulses for operate = 5
The pulses in the specified direction from Directional mode are counted. If the pulse counter reaches the
set value of the parameter No. of pulses for operate, the directional counter criterion is fulfilled.
The setting of parameter No. of pulses for operate depends on the Operating mode.
Protection and Automation Functions
6.14 Directional Intermittent Ground-Fault Protection
SIPROTEC 5, Overcurrent Protection, Manual 559
C53000-G5040-C017-8, Edition 07.2017