Siemens SIPROTEC 7SK80, Manual

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Functions
2.20 Auxiliary Functions
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A5, Release date 11.2012 271
Σ
I Procedure
Being the basic function of summation current formation, the
Σ
I -procedure is always active and does not
require any additional settings. This is irrespective of the configuration in address
172 52 B.WEAR MONIT
.
This method does not offer integrated threshold evaluation. The latter could, however, be implemented using
CFC.
Σ
I
x
Procedure
Parameter
172 52 B.WEAR MONIT
can be set to activate the
Σ
I
x
procedure. In order to facilitate evaluating
the sum of all tripping current powers, the values are referred to the involuted CB rated operational current.
This value is indicated in the CB data at address
260 Ir-52
in the
P.System Data 1
and can be set as
primary value. This reference allows the threshold of the
Σ
I
x
procedure to correspond to the maximum number
of make-break operations. For a circuit breaker, whose contacts have not yet been worn, the maximum number
of make-break operations can be entered directly as threshold. The exponent for the involution of the rated op-
erational current and of the tripping currents is set at address
264 Ix EXPONENT
. To meet different customer
requirements, this exponent
264 Ix EXPONENT
can be increased from
1.0
(default setting =
2.0
) to
3.0
.
For the procedure to operate correctly, the time response of the circuit breaker must be specified in parameters
266 T 52 BREAKTIME
and
267 T 52 OPENING
.
The summated values can be interpreted as the number of tripping operations at rated operational current of
the CB. They are displayed in the statistical values without unit and with two decimal places.
2P-Procedure
Parameter
172 52 B.WEAR MONIT
can be set to activate the 2P procedure. An operating cycles diagram (see
sample diagram in the functional description of the 2P procedure), provided by the manufacturer, shows the
relationship of make-break operations and tripping current. The two vertices of this characteristic in a double
logarithmic scale are decisive for the setting of addresses
260
to
263
:
Point P1 is determined by the number of permitted make-break operations (parameter
261 OP.CYCLES AT
Ir
) for rated operational current I r (parameter
260 Ir-52
)
Point P2 is determined by the maximum number of make-break operations (parameter
263 OP.CYCLES Isc
)
for rated fault tripping current I sc (parameter
262 Isc-52
).
For the procedure to operate correctly, the time response of the circuit breaker must be specified in parameters
266 T 52 BREAKTIME
and
267 T 52 OPENING
.
I
2
t-Procedure
The I
2
t-procedure is activated via configuration parameter
172 52 B.WEAR MONIT
. The square fault current
integrals are referred to the squared device nominal current. For purposes of determining the arc time, the
device must be informed of the CB tripping time
T 52 BREAKTIME
as well as the CB opening time
T 52
OPENING
of the circuit breaker. For recognition of the last zero crossing (arc deletion) of the currents after trip-
ping, the „Current-zero“ Criterion is required.