Basler Electric BE1-851 - Manual (Page 192)

Reclosing can be disabled by IN2 or Virtual Switch 143 that interrupts the RI input to the recloser function
block. In this scheme, enabling the recloser after a “one shot” trip will cause the recloser to start the
reclosing sequence and automatically close the breaker. If the control switch slip contact is in the after trip
position, the recloser will not automatically start. If an external control switch slip contact is used, it should
be wired in series with the reclose enable switch to IN2.
The BESTlogic can be modified so that the reclosing disable logic drives the recloser to lockout instead of
interrupting the RI input. This is accomplished by using variables IN2, 143, and 101SC in the DTL
expression instead of the RI expression. This recloser control logic is used in preprogrammed logic
scheme Feeder_3.
The recloser will be driven to lockout if a breaker failure occurs.
Setting an appropriate logic expression for 79ZONE can enable zone-sequence coordination. Zone-
sequence uses a BESTlogic expression but is not within the logic settings. The Feeder_4 logic scheme
uses the expression SP-79ZONE=VO12.
Feeder_4 logic provides for the recloser to torque control the 50TP/N/Q functions (typically used for low
set instantaneous protection) during various steps in the reclosing sequence. Setting the recloser
sequence controlled blocking output in the four setting groups is done using the S#-79SCB command.
Blocking of external instantaneous elements is done through OUT3.
Recloser timing is stopped by the wait input if an overcurrent protection function block is picked up and
timing. This prevents the reset timer from resetting the reclose function for a situation where a 51 element
is just above pickup and the time to trip is longer than the reset time.
A block load tap changer output is not provided in this scheme. OUT5 can be reprogrammed as a 79RNG
(recloser running/block tap changer) output and wired to energize a normally closed auxiliary relay.
Normal Operation - Bus Protection
When any of the 50T or 51 function blocks is picked up, OUT4 closes. The signal from OUT4 is wired to
IN2 of the upstream relay using BUS logic. The upstream relay blocks the 150T elements that are set up
to trip the bus breaker or bus lockout relay. If the fault is not on a feeder, the 150T elements of the bus
relay are not blocked. The bus relay 150T elements are set with a time delay of 2 to 20 cycles to provide
a coordination interval for the feeder relay OUT4 to close or the redundant feeder relays to trip the feeder
breaker. Should there be a problem with the blocking logic, the bus relay 51 functions are not blocked to
allow bus fault clearing with a traditional coordination interval.
When used to provide high-speed overcurrent protection for the substation bus, it is recommended that all
51 function timing curves be set for instantaneous reset. Use of this protection feature with redundant
electromechanical relays should be done with caution. Retrofit of the electromechanical relays with BE1-
50/51B solid-state overcurrent relays can mitigate this concern.
Normal Operation - Alarms
Two alarm logic variables drive the front panel alarm LEDs: Major alarm (ALMMAJ) and Minor alarm
(ALMMIN). ALMMAJ is set to drive the fail-safe output OUTA. ALMMIN is not set to drive an output relay.
The logic can be modified to place ALMMIN in the BESTlogic expression for VOA if all alarms are to be
combined. ALMMIN can be placed in the BESTlogic expression for another output if it is desired that
these conditions be enunciated separately.
Contingency Operation - Test Mode
The test mode is intended to increase the security of the feeder protection and control system if external
test switches are not installed on all outputs. When the relay is out of service for testing, the breaker
failure, automatic reclosing, and block upstream instantaneous functions are disabled. Backup by the
upstream relay is enabled.
De-energizing IN4 or closing Virtual Switch 343 will put the logic in test mode. IN4 can be controlled by a
panel mounted selector switch that is closed in the normal state and open in the test state. IN4 can also
be controlled by a standard external test switch that is opened with the rest of the test switch poles.
The logic expression for test mode drives virtual output 15 (VO15). This virtual output is alarm bit #23 in
the programmable alarm mask. It can be masked to drive an alarm LED to provide indication when the
relay is in Test Mode.
8-36 BE1-851 Application 9289900990 Rev R