Basler BE1-951, Инструкция по эксплуатации

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4-52 Protection and Control BE1-951
D2843-06
03-14-00
INI
Mode =
0-disable
1-enable
B R E A K E R
F A I L U R E
(BF)
B L K
B F P U
B F T
Figure 4-36. Breaker Failure Element
Retrieving 62/162 Output Status Information from the Relay
The status of each logic variable can be determined from the ASCII command interface by using the
RG-STAT (report general-status) or the RL (report logic) commands. See Section 6, Reporting and Alarm
Functions, General Status Reporting for more information.
BREAKER FAILURE PROTECTION
BE1-951 relays provide one function block for breaker failure protection. This function includes a timer and
a current detector. Figure 4-36 shows the BF function block. The function block has two outputs BFPU
(breaker failure pickup) and BFT (breaker failure trip).
An INI (Initiate) logic input is provided to start the breaker failure timer. When this expression is true and
current is flowing in the phase current input circuits, the breaker failure timer is started. Supervision of the
initiate signal can be designed in BESTlogic. Once the breaker failure timer is started, the initiate signal
does not have to remain true.
A BESTlogic expression defines how the BLK (Block) input
functions. When this expression is TRUE, the element is
disabled by forcing the outputs to logic 0 and resetting the
timer to zero. For example, this may be an input wired to a
test switch such that breaker failure protection is disabled
when the primary protective elements are being tested to
prevent inadvertent backup tripping during testing.
The breaker failure timer is stopped by the fast-dropout
current detector function. See Section 3 Input and Output
Functions, Current Measurement for more details on this
function. The fast-dropout current detector is designed to
directly determine when the current in the poles of the
breaker has been interrupted without having to wait for the
fault current samples to clear the one-cycle filter time used by the normal current measurement function.
This function has less than one cycle dropout time. The timer can also be stopped by the block logic input
being asserted.
The current detector sensitivity is fixed at 10 percent of nominal. A traditional breaker failure relay includes
a fault detector function that serves two independent purposes: current detection and fault detection. A
current detector is generally included to stop breaker failure timing when it is determined that current flow
in all poles of the breaker has stopped. The secondary function of a traditional fault detector is to provide
an independent confirmation that a fault exists on the system and to increase security from mis-operation
caused by an inadvertent initiate signal. To do this, a fault detector by definition must be set above load
current which reduces its sensitivity as a current detector. Since this breaker failure timer is included in a
multifunction protection system, fault detector supervision is not required.
If external relays are used to initiate the breaker failure timer, it may be desirable to include fault detector
supervision of the initiate signal using an instantaneous overcurrent function in BESTlogic. For example, if
it is desired that certain initiate signals be supervised by a fault detector, it is possible to AND them with one
of the 50T protective functions using a virtual output expression. In other applications, it may be desirable
to have breaker failure timing with no current detector supervision. In this case, one of the general purpose
logic timers (device 62) can be used as a breaker failure timer. See Section 8, Application, Application Tips
for more details on this application.
When the breaker failure timer is picked up, the BFPU logic output is TRUE. This output would typically be
used as a re-trip signal to the protected breaker. This can provide an independent tripping signal to the
breaker that may also open the breaker to prevent backup tripping.
If the current detector remains picked up for the duration of the breaker failure delay time, the BFT output
is asserted. This output would normally be used to trip an 86F lockout relay which will trip and prevent
closing of adjacent breakers and/or key transfer trip transmitters.
Courtesy of NationalSwitchgear.com