Functions
2.18 Auxiliary Functions
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
253
Σ I
x
Procedure
Parameter 172 52 B.WEAR MONIT can be set to activate the ΣI
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 ΣI
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 addresses260 to 263:
Point P1 is determined by the number of permitted make-break operations (parameter 261 OP.CYCLES AT
Ir) for rated operational current Ir (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 Isc (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.
To Next Page
Loading...
Need help?
General
