Siemens siprotec SJ62 User Manual page 331

2 Functions
Σ I Procedure
Σ I
x
Procedure
329
The following diagram illustrates the relationship between these CB times.
Figure 2-120 Illustration of the CB times
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.
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 configu-
ration in address 172 52 B.WEAR MONIT. This method does not offer integrated
threshold evaluation. The latter could, however, be implemented using CFC.
Parameter 172 52 B.WEAR MONIT can be set to activate the ΣI
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
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 operational 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.
x
procedure to correspond to the maximum
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
x
procedure. In order