8-28
BE1-CDS240 Application
9365200990 Rev F
Typically, the CDS240-TXBU-B-BE scheme would be applied with a BE1-851 on the feeder circuits and a
BE1-851 or BE1-CDS240 on the bus main breaker interlocked with the feeder relay to provide high-
speed, bus fault protection. This combination provides independent, overlapping backup protection in the
event of a common mode failure.
Typically, the 87 protection element provides high-speed restrained differential and unrestrained
differential phase and ground protection for faults inside the differential zone. At the same time, it
provides security against misoperation resulting from transformer inrush by restraining and preventing a
trip in the presence of 2
nd
and 5
th
harmonics.
Typically, the 151 protection element is coordinated with the low-side bus protection to provide Phase,
Neutral, and Negative Sequence timed backup protection for the low-side bus if the bus protection is out
of service.
Typically, the 251 protection element is coordinated with the low-side feeder protection to provide Phase,
Neutral, and Negative Sequence timed backup protection for feeder faults if the feeder protection is out of
service.
Typically, the 51N protection element is coordinated with the low-side bus and feeder protection to
provide Neutral (ground) timed backup protection for transformer low side, bus, and feeder ground faults
if any primary zone of protection is of service.
Typically, the 250T protection element is set to coordinate with a high-speed bus-interlocking scheme
(851 or BE1-CDS240) to provide a definite time coordination interval of 18 to 20 cycles for bus fault
backup protection. The 250T protection element should have a pickup setting greater than the highest
feeder instantaneous element to ensure that it will not pickup before any feeder relay.
Typically, the 50T protection element is set to provide fault detection but not to be picked-up on load. This
element provides current supervision for the external BFI input associated with the BF protection element.
Integration of Protection, Control, and I/O Elements
The logic settings in Table 8-19 also include the logic equations that establish the control connections
between elements of the CDS240-TXBU-B-BE scheme. For example, the two underlined commands in
the settings of Table 8-19 provide the electrical connection between the 87 element (trip enabled by the
program) and Trip Outputs 1 and 4. Referring to Figures 8-7, 8-8, and 8-9, 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 CDS240-TXBU-B-BE scheme is hard wired from the feeder protection relays (851) (not
shown on Figure 8-9) allowing the CDS240-TXBU-B-BE scheme to signal (through output 6) to the
primary bus protection scheme (851 or CDS) to switch to Feeder Backup Mode. This signaling method
was chosen because of limited 851 I/O. Input 6 of the CDS240-TXBU-A-BE 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 is 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 CDS240-TXBU-B-BE
scheme. Input 5 to the CDS240-TXBU-B-BE 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 CDS240-
TXBU-B-BE 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.
Summary of Contents for BE1-CDS240
Page 2: ......
Page 8: ...vi BE1 CDS240 Introduction 9365200990 Rev F This page intentionally left blank ...
Page 38: ...1 28 BE1 CDS240 General Information 9365200990 Rev F This page intentionally left blank ...
Page 40: ...ii BE1 CDS240 Quick Start 9365200990 Rev F This page intentionally left blank ...
Page 152: ...ii BE1 CDS240 Metering 9365200990 Rev F This page intentionally left blank ...
Page 226: ...iv BE1 CDS240 Application 9365200990 Rev F This page intentionally left blank ...
Page 286: ...ii BE1 CDS240 Security 9365200990 Rev F This page intentionally left blank ...
Page 290: ...9 4 BE1 CDS240 Security 9365200990 Rev F This page intentionally left blank ...
Page 292: ...ii BE1 CDS240 Human Machine Interface 9365200990 Rev F This page intentionally left blank ...
Page 306: ...10 14 BE1 CDS240 Human Machine Interface 9365200990 Rev F This page intentionally left blank ...
Page 308: ...ii BE1 CDS240 ASCII Command Interface 9365200990 Rev F This page intentionally left blank ...
Page 342: ...11 34 BE1 CDS240 ASCII Command Interface 9365200990 Rev F This page intentionally left blank ...
Page 349: ...Figure 12 5 Horizontal Rack Mount Front View 9365200990 Rev F BE1 CDS240 Installation 12 5 ...
Page 361: ...Figure 12 17 Typical DC Connection Diagrams 9365200990 Rev F BE1 CDS240 Installation 12 17 ...
Page 372: ...12 28 BE1 CDS240 Installation 9365200990 Rev F This page intentionally left blank ...
Page 468: ...13 92 BE1 CDS240 Testing and Maintenance 9365200990 Rev F This page intentionally left blank ...
Page 512: ...14 42 BE1 CDS240 BESTCOMS Software 9365200990 Rev F This page intentionally left blank ...
Page 544: ...ii BE1 CDS240 Terminal Communication 9365200990 Rev F This page intentionally left blank ...
Page 550: ...ii BE1 CDS240 Settings Calculations 9365200990 Rev F This page intentionally left blank ...
Page 578: ...D 28 BE1 CDS240 Settings Calculations 9365200990 Rev F This page intentionally left blank ...
Page 579: ......