Basler Electric BE1-851 - Manual (Page 200)

SL-143 = 2
SL-243 = 2
SL-343 = 2
SL-101 = 1
SL-VOA = ALMMAJ
SL-VO1 = VO11+BFPU+101T
SL-VO2 = 79C+101C
SL-VO3 = /79SCB
SL-VO4 = VO12*/VO5*IN4*/343
SL-VO5 = BFT
SL-VO6 = 0
SL-VO7 = 0
SL-VO8 = IN2*/143*101SC
SL-VO9 = VO5
SL-VO10 = VO11+IN3*150TPPU+IN3*150TNPU
SL-VO11 = 50TPT+50TNT+51PT+51NT
SL-VO12 = 50TPPU+50TNPU+51PPU+51NPU
SL-VO13 = 0
SL-VO14 = 0
SL-VO15 = /IN4+343
Bus and Backup Logic Schemes
Logic schemes BUS and BACKUP are meant for use on a bus main breaker, and provide all overcurrent
protection and control functions required for a typical bus main breaker in a non-directional overcurrent
protection application. These logic schemes are intended for use in conjunction with other programmable
relays using the Feeder_1, Feeder_2, and Feeder_3 logic schemes to provide complete overcurrent
protection for the transformers, bus, and feeders in a radial system substation.
The components of BUS logic are summarized in Tables 8-21 through 8-24. Figure 8-11 is a one-line
diagram of BUS logic and Figure 8-12 is a diagram representing the logic settings and equations of BUS
logic.
The components of BACKUP logic are summarized in Tables 8-25 through 8-28. Figure 8-13 is a one-line
diagram of BACKUP logic and Figure 8-14 is a diagram representing the logic settings and equations of
BACKUP logic.
When interconnected with feeder relays using logic scheme Feeder_1, Feeder_2, or Feeder_3, the
BACKUP logic scheme provides complete backup (except for reclosing) for the feeder relays if relay
failure occurs or when they are out of service for testing or maintenance. Figure 8-15 shows the
interconnection of Feeder, BUS, and BACKUP relays to achieve this integrated protection system.
Normal Operation - Control
The virtual breaker control switch is programmed to provide manual trip and close control of the bus
breaker in both BUS and BACKUP logic. The control functions of these logic schemes use both traditional
contact sensing inputs and virtual switches. Virtual switches that are not needed may simply go unused.
The protection engineer may choose to free up contact sensing inputs for other uses by using the virtual
switches exclusively for the various control functions.
Normal Operation - Bus Protection
The BUS relay logic primary task in normal operation is to provide high-speed bus fault protection (2-4
cycles coordination interval) and timed overload or high unbalanced load protection. The BACKUP relay
logic primary task is to backup the Bus relay for bus faults with a coordination interval of 18-20 cycles
When any of the feeder relay overcurrent elements are picked up and timing, OUT4 on the feeder relay
closes. This signal is wired to IN2 of the upstream (primary) bus relay using Bus logic that blocks the 50T
elements. These are set with a delay of 2 to 4 cycles. If the fault is not on a feeder, the 50T elements of
the bus relays are not blocked. The 50T function blocks are set up to trip the bus breaker by an external
bus lockout relay (86B) via OUT4. The BACKUP relay does not get blocked when the feeder relays are
picked up so its 50T elements are set with a time delay long enough to allow the feeder breaker to
8-44 BE1-851 Application 9289900990 Rev R