Siemens SIPROTEC 7SD610 User Manual

2 Functions
98
7SD610 Manual
C53000-G1176-C145-4
three phase currents of three star-connected current transformers must be available
and connected.
For the directional Iph>stages, the used measuring voltage is determined by the fault
condition. The selection occurs according to the availability of the measured values
listed below.
The current phase earth voltage is used
• for single-pole or three-pole faults,
• if phase-earth voltage > 4V
• not within the first 50 ms after short-circuit, as the current voltage is then disturbed
by transients.
The saved phase-earth voltage is used
• for single-pole or three-pole faults,
• up to a maximum of 2 s after saving the phasors
• if there was no triggering or single-pole pause prior to the short-circuit.
The unfaulted current phase-earth voltage is used
• for single-pole faults
• for undisturbed unfaulted phase-earth voltages
• if the voltage level is > 70% of the rated voltage.
The negative sequence systems U
2
and I
2
are used
• for single-pole or two-pole faults
•ifI
2
> 50 mA and U
2
> 5V.
If the negative sequence systems are used in the case of two single-pole short-cir-
cuits, the most powerful short circuit is valid for direction determination.
The current voltage is used if it is > 5V.
If none of the previously measuring values is available, an already existing result of
the direction determination is used, or the directional stage is blocked for the respec-
tive phase.
For the directional 3I0>stages the used measuring voltage is determined by the pa-
rameter 2603Direct. 3I0.
• If with U0/I0 has been set, the current zero sequence values 3U
0
and 3I
0
are
used. If the zero sequence voltage is too small for a direction measurement, the
directional 3I0>stages are blocked.
• If with U2/I2 has been set, the current negative sequence values 3U
2
and 3I
2
are used. If the negative sequence voltage is too small for a direction measurement,
the directional 3I0>stages are blocked.
• If U0/I0 or U2/I0 has been set, negative sequence or zero sequence values
can be used. Negative sequence system values are used if they are larger then the
respective zero sequence system values. If the measuring variables of both
systems are unavailable, the directional 3I0>stages are blocked.
Note
During a measuring voltage failure, all directional stages are blocked.
During the single-pole dead time, all earth current stages are blocked.
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Siemens SIPROTEC 7SD610 Specifications

General

Brand	Siemens
Model	SIPROTEC 7SD610
Category	Relays
Language	English