Basler BE1-CDS220, Instruction Manual

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BE1-CDS220 Application 8-37
protection element from the transformer BE1-CDS220 (not shown in Figure 8-12) does not get blocked
when the feeder relays are picked up. Therefore, the 250T protection element must be set with a time
delay long enough to allow the feeder breaker to interrupt the fault.
Virtual control switch elements enabled for use in this scheme are 101, 43, and 743. The 101 control
switch trips the low-side breaker through output 4 and closes the low-side breaker through output 5.
Control switch 43 is used to turn the 87 function on or off and 743 us used to enable Test Mode.
Test Mode
When virtual control switch 743 is enabled, breaker failure initiate through output 6 is defeated.
Setting Group
For normal operation, setting group 0 is active for the BUS-W-BU scheme. IN7 to the BE1-CDS220
identifies when a feeder relay (851) is out of service. At the same time, IN5 of the transformer BE1-
CDS220 scheme gets the same signal. Both relays then switch to setting group 1. Setting group selection
mode 2, binary coded selection, is used to recognize the group setting state. When input D0 to the setting
group selection element is a one, it is interpreted as a binary 1 causing the logic to switch to group 1.
When the bus BE1-CDS220 is in setting group 1, it is operating in feeder backup mode. This expression is
programmed to virtual output 14 which drives alarm bit #22 in the programmable alarm mask. It can be
masked to drive an alarm LED and alarm display to indicate when the relay is in feeder backup mode and
to trip a feeder breaker instead of the bus breaker.
Alarms
Three logic variables drive the front panel LEDs: Relay Trouble (ALMREL), Major Alarm (ALMMAJ), and
Minor Alarm (ALMMIN). A fourth logic variable, Logic Alarm (ALMLGC), has no associated front panel
LED. When the relay self-test detects a problem in the relay (ALMREL) as programmed for the BUS-W-
BU scheme, the Relay Trouble LED lights, output A operates, and all outputs are disabled. When a Major
Alarm is detected (ALMMAJ), the associated LED lights, but in this scheme, no output relay is
programmed to operate. When a Minor Alarm (ALMMIN) is detected, the associated LED lights, but in this
scheme, no output relay is programmed to operate.
CAUTION
Test Mode Enable does not defeat the trip outputs of the relay. External trip test
blades must be opened or the BUS-W-BU logic scheme must be modified to suit
the user’s test mode requirements. One option is to trip the breakers through an
86 device only. Typically, 86 devices are installed with test blades in the breaker
trip circuit so that the protection scheme can be safely operational checked while
the primary equipment is in service. Another option is to inhibit all trip outputs
when test mode is enabled; however, external devices such as auxiliary relays
and 86 devices would no longer be included in the operational test.
NOTE
Tables 8-22 through 8-25 provide detailed logic definitions for the inputs, outputs,
protection, and control elements. Only those inputs, logic blocks, virtual switches,
and outputs in use for the BUS-W-BU preprogrammed logic are described in the
following Tables.