The operational logic consists of the following:
• input magnitude processing
• input magnitude selection
• threshold comparator
• block signal check
• time delay characteristics
• output processing.
The inputs of the function are the following:
• operating mode selections
• setting parameters
• digital input signals
• measured and pre-processed current magnitudes.
The function' output signals can be used for direct I/O controlling and user logic programming. The
function generates general time-stamped ON/OFF events to the common event buffer from each of the
two (2) output signals. The time stamp resolution is 1 ms. The function also provides a resettable
cumulative counters for RETRIP, CBFP, CBFP START and BLOCKED events.
The following figure presents a simplified function block diagram of the circuit breaker failure protection
function.
Figure. 5.3.8 - 101. Simplified function block diagram of the CBFP function.
Measured input
The function block uses analog current measurement values. It always uses the RMS magnitude of the
current measurement input. The user can select I01, I02 or the calculated I0 for the residual current
measurement. A -20 ms averaged value of the selected magnitude is used for pre-fault data
registering.
Table. 5.3.8 - 87. Measurement inputs of the CBFP function.
Signal
Description
Time base
IL1RMS
RMS measurement of phase L1 (A) current
5ms
IL2RMS
RMS measurement of phase L2 (B) current
5ms
A
AQ
Q-T215
-T215
Instruction manual
Version: 2.04
142
