Basler BE1-CDS240, Instruction Manual

Page: 180 / 580

function (SB-LOGIC). Figure 6-10 illustrates breaker status (SB-LOGIC) during a fault and protective trip.
Table 6-11 serves as a legend for the call-outs of Figure 6-10.
The relay sums the N
th
power of the currents that are interrupted and will set the breaker duty alarm when
the sum exceeds the N
th
power of the maximum breaker duty (D
max
) setting. The user must enter a value
for N and a value for D
max
.
To determine N and D
max
, the user needs to find two measurements of allowable breaker wear. These
levels would typically be the maximum number of operations at load level currents and the maximum
number of operations at maximum fault rating.
Point 1; # Ops @
Imax load
Point 2; # Ops @ I
max fault
To determine the breaker wear exponent N, using the above data points as an example, apply this
equation:













load max
fault max
fault max
load max
I
I
log
I @ Ops #
I @ Ops #
log
N
N can be any value from 1 to 3.
Using values for I
max load
and I
max fault
in primary amperes (the relay multiplies by the CTR before doing
calculations), the value for maximum breaker duty, D
max
, is calculated from either of these two equations:
 
 
1/N
load max
N
load max max
I @ Ops # I D
 
 
 
1/N
fault max
N
fault max max
I @ Ops # I D
 
Both of the last two equations should yield the same value for D
max
.
When testing the relay by injecting currents into the relay, the values in the duty registers should be read
and recorded prior to the start of testing. Once testing is complete and the relay is returned to service, the
registers should be reset to the original pre-test values. A block accumulation logic input may be used
when testing so that simulated breaker duty is not added to the duty registers. The BLKBKR logic function
is an OR logic term (e.g., IN1 or VO7) which blocks the breaker monitoring logic when TRUE (1).
BLKBKR is set to zero to disable blocking. When breaker monitoring is blocked (logic expression equals
1), breaker duty is not accumulated.
6-20 BE1-CDS240 Reporting and Alarm Functions 9365200990 Rev F