Siemens SIPROTEC 7SJ62 Manual page 348

Functions
2.23 Auxiliary Functions
Figure 2-134
Current flow monitoring 212 BkrClosed I MIN, which some protective functions rely upon to detect a closed
CB, is used as the current zero criterion. It should be set with respect to the actually used device functions (see
also margin heading „Current Flow Monitoring (CB)" in Section 2.1.3.2.
Σ I Procedure
Being the basic function of summation current formation, the ΣI-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 ΣI
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
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 264Ix 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.
348
Illustration of the CB times
x
procedure. In order to facilitate evaluating
x
procedure to correspond to the maximum number
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008