Basler BE1-CDS220, Instruction Manual

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BE1-CDS220 Application 8-23
Integration of Protection, Control, and I/O Elements
The logic settings in Table 8-16 also include the logic equations that establish the control connections
between elements of the TX-W-BU scheme. For example, the two underlined commands in the settings of
Table 8-16 provide the electrical connection between the 87 element (trip enabled by the program) and trip
outputs 1 and 4. Referring to Figures 8-9 and 8-10, the 87 protection element trips through outputs 1 and
4. The 151 and 51N protection elements (also trip enabled by the settings) trip through output 1. The 251
protective element trips through output 4. The 250 protection element trips through output 2 and the BF
element trips through output 3. Protection elements set at 0 are setting disabled and will not provide a trip
output even if logic enabled.
Input 5 of the TX-W-BU scheme is hard wired from the feeder protection relays (851) (not shown on
Figure 8-8) allowing the TX-W-BU scheme to signal (through output 6) to the primary bus protection
scheme (851 or CDS220) to switch to Feeder Backup Mode. This signaling method was chosen because
of limited 851 I/O. Input 6 of the TX-W-BU scheme is a contact supervised BFI input and Input 7 is a
current supervised BFI input.
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.
Setting group selection mode 2, binary coded selection, is used to recognize the group setting state.
When Input D0 of the setting group selection element is high, it is interpreted as a binary 1 causing the
logic to switch to group 1. For normal operation, setting group 0 is active for the TX-W-BU scheme. Input 5
to the TX-W-BU scheme indicates when a feeder relay is out of service and causes a switch from setting
group 0 to setting group 1. At the same time, output 6 of the TX-W-BU scheme provides an input to the
primary bus protection relay.
Test Mode
When virtual control switch 743 is enabled, all breaker failure functions are defeated.
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 TX-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 TX-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.