Basler Electric BE1-BPR - Manual (Page 82)

4-30 BE1-BPR Functional Description 9272000990 Rev J
BKROPS Command
Purpose:
Read or change breaker operations data.
Syntax: BKROPS[=<#operations>,<breaker close logic>]
Comments: An access area 1 or 3 password is required to change settings. Breaker close logic is
defined using any contact sensing input that is true when the breaker is closed. True logic
indicates a closed breaker; false logic indicates an open breaker. # operations
increments when the breaker closes.
BKROPS Command Example:
Set the breaker operations counter at zero and use contact input 1 to sense the breaker status (52a
contact finger).
BKROPS=0,I1
Breaker contact duty log, DLOG, is stored in nonvolatile memory and contains the approximate duty or
contact wear on each pole (phase) of the breaker represented as a percentage of a maximum, DMAX. A
52a or 52b input is required for this diagnostic and the timing relationship between the auxiliary contact
finger and the main breaker contacts should be known for maximum accuracy. The duty percentage value
for each pole can be programmed through the front panel controls or through a communication port using
the DLOG command. The log may be reset to zero after maintenance or set at a specific percentage
value when the relay is put into service by using the DLOG command.
Breaker Contact Duty Diagnostics (Enhanced Relays Only)
The duty value for each pole of the breaker, D[p], is compared against a maximum value, DMAX. If D[p]
for any pole of the breaker exceeds DMAX, a diagnostic alarm is set to true and remains set until the D[p]
value for the appropriate pole(s) are reset. Using the programmable logic, a virtual output can drive an
output relay to provide an indication that the breaker needs service. To do this, use the PDIAG command
to enable the DLOG diagnostic alarm to turn on O14 or O15 when DLOG[p] exceeds 100 percent. Then
use the LO command to use O14 or O15 to drive output O1 - O5.
DMAX is programmable in amperes-squared seconds (A
2 -S) in exponential notation. For example, 2
times 10 6 A 2 -S would be entered as 2.0E6). DMAX is an approximation that can be refined as further
experience with a particular type of breaker is obtained. Changing DMAX will automatically update the
value in the DLOG to a new percentage based on the new DMAX value.
Users may find it difficult to obtain a setting for DMAX since no standard recommends the interrupting
duty limits for breakers. The following formula is offered as a guide and should be superseded by
manufacturers data when available.
If a breaker manufacturer published the maximum number of safe operations (N), at the full-rated
interrupting current value (Ir), assume that the average arcing time (ta) is ½ cycle.
The duty limit setting is then calculated as
F
1
2
1
I N DMAX
n
r
⋅ ⋅ 





⋅ =
For example, if I
r
equals 50 kA, N equals 10, n equals 2, and the frequency equals 60 Hz, DMAX is
calculated as follows.
60
1
2
1
50,000 10 DMAX
2
⋅ ⋅ ⋅ =
6
10 208 DMAX ⋅ =
A lower value of DMAX may be selected until a reliable correlation is found between contact wear and the
accumulated interrupted duty.
The duty on each pole is accumulated and calculated as follows for each breaker opening:
where:
∞
D[p] = ∑(CTP • I[p][n]) 2 (Tbo)
N=1
D[p] = Breaker duty for pole p
p = Phase identification number where 1/2/3=a/b/c
CTP = Phase current transformer step-down ratio