Basler BE1-CDS240 User manual

INSTRUCTION MANUAL
FOR
CURRENT DIFFERENTIAL SYSTEM
BE1-CDS240
Publication: 9365200990
Revision: F 12/08

INTRODUCTION
This instruction manual provides information about the operation and installation of the BE1-CDS240
Current Differential System. To accomplish this, the following information is provided:
General information, specifications, and a Quick Start guide.
Functional description and setting parameters for the input/output functions, protection and control
functions, metering functions, and reporting and alarm functions.
BESTlogic programmable logic design and programming.
Documentation of the preprogrammed logic schemes and application tips.
Description of security and user interface setup including ASCII communication and the human-
machine interface (HMI).
Installation procedures, dimension drawings, and connection diagrams.
Description of the front panel HMI and the ASCII command interface with write access security
procedures.
A summary of setting, metering, reporting, control, and miscellaneous commands.
Testing and maintenance procedures.
Appendices contain time overcurrent characteristic curves, overexcitation (24) inverse time curves,
terminal communication, and settings calculations assistance.
Optional instruction manuals for the BE1-CDS240 include:
Distributed Network Protocol (DNP) 3.0 (9365200991)
Modbus(9365200992).
WARNING!
To avoid personal injury or equipment damage, only qualified personnel should
perform the procedures in this manual.
NOTE
Be sure that the relay is hard-wired to earth ground with no smaller than 12 AWG
copper wire attached to the ground terminal on the rear of the unit case. When
the relay is configured in a system with other devices, it is recommended to use a
separate lead to the ground bus from each unit.
9365200990 Rev F BE1-CDS240 Introduction i

First Printing: March 2003
Printed in USA
© 2008 Basler Electric, Highland Illinois 62249 USA
All Rights Reserved
December 2008
CONFIDENTIAL INFORMATION
of Basler Electric, Highland Illinois, USA. It is loaned for confidential use, subject
to return on request, and with the mutual understanding that it will not be used in
any manner detrimental to the interest of Basler Electric.
It is not the intention of this manual to cover all details and variations in equipment, nor does this manual
provide data for every possible contingency regarding installation or operation. The availability and design
of all features and options are subject to modification without notice. Should further information be
required, contact Basler Electric.
BASLER ELECTRIC
ROUTE 143, BOX 269
HIGHLAND IL 62249 USA
http://www.basler.com, [email protected]
PHONE [phone] FAX [phone]
ii BE1-CDS240 Introduction 9365200990 Rev F

9365200990 Rev F BE1-CDS240 Introduction iii
REVISION HISTORY
The following information provides a historical summary of the changes made to the BE1-CDS240
hardware, firmware, and software. The corresponding revisions made to this instruction manual
(9365200990) are also summarized. Revisions are listed in reverse chronological order.
BESTCOMS Software
Version and Date Change
2.05.00, 12/08 Added Power Supply Option 3 (24 Vdc) on Style Number screen on
General Info tab.
Added Power Flow Polarity setting under VTP Setup on Power
System / VT Setup tab.
2.04.07, 04/08 Enhanced BESTCOMS error reporting.
2.04.06, 03/08 Added the ability to turn off delta compensation for Yy0 connections.
Improved Settings Compare function.
2.04.05, 11/06 Added 59X (auxiliary) function.
Added IEC transformer setup.
2.03.00, 03/04 Enhanced overexcitation (24) function.
2.02.00, 09/03 Initial release
Firmware
Version and Date Change
App: 1.04.00, 12/08
DSP: 1.03.02, 12/08 Added Power Flow Polarity setting for VTP Setup.
App: 1.03.02, 03/08
DSP: 1.03.01, 11/06 Added alternate DST (Daylight Saving Time) settings.
Increased immunity to noise on IRIG input.
Improved breaker fail targeting.
Improved x62 timer when changing setting groups.
App: 1.03.00, 09/06
DSP: 1.03.01, 11/06 Added 59X (auxiliary) element.
Added 180compensation parameter for the 87T function.
Enhanced 60FL functionality.
App: 1.02.01, 02/04
DSP: 1.02.01, 01/04 Enhanced overexcitation (24) function.
Added virtual restraint feature.
Relocated logic bits for 62, 162, 262, and 362.
Added separate logic bits for 2nd Harmonic A, B, and C.
Added separate logic bits for 5th Harmonic A, B, and C.
App: 1.01.05, 09/03
DSP: 1.01.00, 06/03 Initial release
Hardware
Version and Date Change
V, 12/08 Release firmware version 1.04.00 and BESTCOMS version 2.05.00.
U, 09/08 EEPROM replacement.
T, 04/08 Release BESTCOMS version 2.04.07.
S, 04/08 Improved response time of contact sense inputs.
R, 03/08 Release firmware version 1.03.02 and BESTCOMS version 2.04.06.
Q, 10/06 Release firmware version 1.03.00 and BESTCOMS version 2.04.05.

iv BE1-CDS240 Introduction 9365200990 Rev F
Hardware
Version and Date Change
N, 08/05 Release firmware version 1.02.00.
M, 11/04 Improved overlay to fit front panel.
L, 03/04 Minor changes to enhance production efficiency.
K, 02/04 Increased the size of the insertion/extraction lever in order to allow
the relay to be inserted/removed from the case more easily.
J, 12/03 Changed from surface mount to through hole connectors on I/O
board.
H, 10/03 Relocated slots on top cover.
G, 10/03 Minor changes to enhance production efficiency.
F, 10/03 Initial release
Manual
Revision and Date Change
F, 12/08 Added information to support Power Supply Option 3 (24 Vdc).
Added Power Flow Polarity setting for VTP Setup in Section 3.
Updated Contact Sensing Input ranges and burden data for re-
designed contact sense circuit.
E, 03/08 Added manual part number and revision to footers.
Added Settings Compare to the end of Section 6.
Added alternate DST (Daylight Saving Time) settings.
Updated terminal numbering in Figures 13-15, 13-16, 13-17, and 13-
18.
D, 10/06 Added 59X (auxiliary) feature.
Added IEC Transformer Setup to Section 3.
Updated all BESTCOMS screen shots.
Updated Table 6-3, Logic Variable Status Report Format, with new
logic bits for 59XPU and 59XT.
C, 03/04 Enhanced the 24 feature.
Added virtual restraint.
Minor text edits.
B, 10/03 Initial release

9365200990 Rev F BE1-CDS240 Introduction v
CONTENTS
SECTION 1 GENERAL INFORMATION ................................................................................................ 1-1
SECTION 2 QUICK START....................................................................................................................2-1
SECTION 3 INPUT AND OUTPUT FUNCTIONS................................................................................... 3-1
SECTION 4 PROTECTION AND CONTROL......................................................................................... 4-1
SECTION 5 METERING......................................................................................................................... 5-1
SECTION 6 REPORTING AND ALARM FUNCTIONS.......................................................................... 6-1
SECTION 7 BESTlogic PROGRAMMABLE LOGIC............................................................................... 7-1
SECTION 8 APPLICATION....................................................................................................................8-1
SECTION 9 SECURITY.......................................................................................................................... 9-1
SECTION 10 HUMAN-MACHINE INTERFACE ................................................................................... 10-1
SECTION 11 ASCII COMMAND INTERFACE..................................................................................... 11-1
SECTION 12 INSTALLATION .............................................................................................................. 12-1
SECTION 13 TESTING AND MAINTENANCE .................................................................................... 13-1
SECTION 14 BESTCOMS SOFTWARE.............................................................................................. 14-1
APPENDIX A TIME OVERCURRENT CHARACTERISTIC CURVES...................................................A-1
APPENDIX B OVEREXCITATION (24) INVERSE TIME CURVES .......................................................B-1
APPENDIX C TERMINAL COMMUNICATION.......................................................................................C-1
APPENDIX D SETTINGS CALCULATIONS ..........................................................................................D-1

vi BE1-CDS240 Introduction 9365200990 Rev F
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9365200990 Rev F BE1-CDS240 General Information i
SECTION 1 GENERAL INFORMATION
TABLE OF CONTENTS
SECTION 1 GENERAL INFORMATION ................................................................................................ 1-1
INTRODUCTION.................................................................................................................................... 1-1
FEATURES............................................................................................................................................ 1-1
I/O Functions ...................................................................................................................................... 1-2
Protection and Control Functions....................................................................................................... 1-3
Metering Functions............................................................................................................................. 1-4
Reporting and Alarm Functions.......................................................................................................... 1-4
BESTlogic Programmable Logic ........................................................................................................ 1-6
Security............................................................................................................................................... 1-6
Human-Machine Interface .................................................................................................................. 1-6
ASCII Command Interface ................................................................................................................. 1-6
Installation .......................................................................................................................................... 1-7
Testing and Maintenance ................................................................................................................... 1-7
BESTCOMS Software ........................................................................................................................ 1-7
PRIMARY APPLICATIONS ................................................................................................................... 1-7
DIFFERENTIAL PROTECTION APPLICATION CONSIDERATIONS .................................................. 1-8
Problem 1: False Differential Current Due to Poor CT Performance................................................. 1-8
Problem 2: Measured Current Magnitude Mismatch ......................................................................... 1-9
Problem 3: Mismatch Caused by Load Tap Changers ...................................................................... 1-9
Problem 4: Phase Angle Shift .......................................................................................................... 1-10
Problem 5: Zero-Sequence Current Sources Within the Zone of Protection ................................... 1-13
Problem 6: Transformer Energization Inrush and Overexcitation .................................................... 1-15
Problem 7: Digital Measurement Errors ........................................................................................... 1-15
MODEL AND STYLE NUMBER DESCRIPTION................................................................................. 1-16
OPERATIONAL SPECIFICATIONS .................................................................................................... 1-17
Metered Current Values and Accuracy ............................................................................................ 1-17
Metered Voltage Values and Accuracy ............................................................................................ 1-17
Metered Frequency Values and Accuracy ....................................................................................... 1-17
Calculated Values and Accuracy ..................................................................................................... 1-18
Energy Data Reporting..................................................................................................................... 1-18
Real-Time Clock............................................................................................................................... 1-18
87 Differential Functions................................................................................................................... 1-18
87ND Neutral Differential Function .................................................................................................. 1-20
Instantaneous Overcurrent Functions .............................................................................................. 1-20
Time Overcurrent Functions............................................................................................................. 1-21
Time Current Characteristic Curves................................................................................................. 1-21
Volts/Hz (24)..................................................................................................................................... 1-21
Phase Undervoltage Function (27P/127P)....................................................................................... 1-22
Negative-Sequence Voltage Protection (47).................................................................................... 1-22
Phase Overvoltage Function (59P/159P)......................................................................................... 1-23
Auxiliary Overvoltage Function 3V0 (59X) ....................................................................................... 1-23
Frequency (81, 181, 281, 381, 481, 581)......................................................................................... 1-23
Breaker Failure (50BF, 150BF, 250BF, 350BF)............................................................................... 1-23
General Purpose Timers (62, 162, 262, 362)................................................................................... 1-24
VT Fuse Loss Monitoring (60FL)...................................................................................................... 1-24
Automatic Setting Group Characteristics ......................................................................................... 1-24
BESTlogic......................................................................................................................................... 1-24
GENERAL SPECIFICATIONS............................................................................................................. 1-24
AC Current Inputs............................................................................................................................. 1-24
Analog to Digital Converter .............................................................................................................. 1-25
Power Supply ................................................................................................................................... 1-25
Output Contacts ............................................................................................................................... 1-25
Control Inputs ................................................................................................................................... 1-25
IRIG .................................................................................................................................................. 1-26
Contact Inputs .................................................................................................................................. 1-26

ii BE1-CDS240 General Information 9365200990 Rev F
Communication Ports ....................................................................................................................... 1-26
Display.............................................................................................................................................. 1-26
Isolation ............................................................................................................................................ 1-26
Surge Withstand Capability .............................................................................................................. 1-26
Radio Frequency Interference (RFI)................................................................................................. 1-27
Electrostatic Discharge (ESD).......................................................................................................... 1-27
Shock................................................................................................................................................ 1-27
Vibration ........................................................................................................................................... 1-27
Environment ..................................................................................................................................... 1-27
UL Recognition ................................................................................................................................. 1-27
C.S.A. Certification ........................................................................................................................... 1-27
GOST-R Certification ....................................................................................................................... 1-27
Patent ............................................................................................................................................... 1-27
Physical ............................................................................................................................................ 1-27
Figures
Figure 1-1. Restrained Differential Characteristic ..................................................................................... 1-8
Figure 1-2. Tap Adjust for Mismatch ......................................................................................................... 1-9
Figure 1-3. Currents on Different Voltage Bases ...................................................................................... 1-9
Figure 1-4. Delta/Wye Transformer Circuits............................................................................................ 1-11
Figure 1-5. Three-Phase Connections, Delta-Wye Configuration, CT Compensation............................ 1-12
Figure 1-6. Three-Phase Connections, Delta-Wye Configuration, Internal Phase Compensation ......... 1-13
Figure 1-7. Traditional Zero-Sequence Trap for Application with Ground Banks ................................... 1-14
Figure 1-8. Style Number Identification Chart ......................................................................................... 1-17
Figure 1-9. Typical 87 Response Characteristic Curves ......................................................................... 1-19
Tables
Table 1-1. Control Input Burden .............................................................................................................. 1-26
Equations
Equation 1-1. Time to Trip ....................................................................................................................... 1-22
Equation 1-2. Time to Reset.................................................................................................................... 1-22

9365200990 Rev F BE1-CDS240 General Information 1-1
SECTION 1 GENERAL INFORMATION
INTRODUCTION
The BE1-CDS240 Current Differential System is an economical, microprocessor based, multifunction
system that provides a four input, three-phase percentage differential with harmonic restraint protection.
Also included is three-phase with voltage control, ground, and negative-sequence overcurrent protection,
voltage and frequency protection, breaker failure for up to four breakers, breaker monitoring for four
breakers, transformer monitoring, and metering functions, all in an integrated system with several
communications options. The BE1-CDS240 Current Differential System is intended for use in any low
impedance current differential protection application including transformer, generator, motor, and bus
protection. Four setting groups are provided for adaptive relaying with automatic selection logic for cold
load pickup and/or dynamic setting group changes.
The BE1-CDS240 can be ordered with 12 programmable contact sensing inputs, 10 programmable
outputs, and one alarm output or eight programmable contact-sensing inputs, 14 programmable outputs
and one alarm output. Outputs can be assigned various functions by logical programming to perform
protection, control, or indicate operations. For example, protection functions can cause a protective trip
operation. Control functions can cause a manual trip, manual close, or automatic reclose operation.
Indicators could be relay alarm, setting group one enable, setting group two enable and others.
Protection scheme designers may select from an embedded pre-programmed logic scheme or from a
number of logic library schemes found in BESTCOMS to perform the most common protection and control
requirements or create a custom scheme using BESTlogic.
The BE1-CDS240 is available in a fully draw-out MX case with configurations for horizontal 19" rack
mounting, horizontal panel mounting and vertical panel mounting. BE1-CDS240 features include:
Up to four restraint inputs (four three-phase current circuits) and two virtual current circuits that
can be used with any combination of two current inputs
Independent ground input
Three voltage inputs (Va, Vb, Vc, to Vn)
Three-phase percentage differential protection with harmonic restraint
Three-phase voltage, frequency and overcurrent protection
Four setting groups
One embedded preprogrammed logic scheme
Fourteen or 10 programmable outputs
Eight or 12 contact sensing inputs
Breaker failure protection for four breakers
Front panel HMI (human-machine interface)
Communications ports: one front RS-232, one rear RS-232, one rear RS-485 and one rear IRIG
port
Communications protocols available: DNP 3.0, Modbus RTU, and ASCII
Sequence of events recording
Fault recording
Oscillography
Demand reporting
Differential current monitoring
Optional load profile reporting
Section 2, Quick Start, provides BE1-CDS240 Current Differential System users with a simplified, "How
To Get Started" procedure.
FEATURES
The BE1-CDS240 includes many features for the protection, monitoring, and control of power system
equipment such as transformers, breakers, buses, generators, and motors. These features include
protection and control functions, metering functions, reporting and alarm functions, and various

1-2 BE1-CDS240 General Information 9365200990 Rev F
communication options. A highly flexible programmable logic system called BESTlogic allows the user to
apply the available functions with complete flexibility and customize the system to meet the requirements
of the protected power system. Programmable I/O, extensive communications features, and an advanced
HMI (human machine interface) provide easy access to the features provided. Through BESTCOMS
software, BE1-CDS240 users with personal computers (PCs) have another easy-access means to
communicate, program, control, and monitor relay/system performance. BESTCOMS is a Windows
(based software application that enhances communication between the PC user and the BE1-CDS240
relay. This software is provided free with every BE1-CDS240 relay. Another software application tool is
BESTWAVE. BESTWAVE is a utility program to view standard COMTRADE (Common Format for
Transient Data Exchange) files like those recorded by Basler Electric multifunction relays. This software is
available free of charge through the Basler website (http://www.basler.com) or Customer Service
Department at +1 618.654.2341.
The following information summarizes the features included in this multifunction device. The organization
of this information outlines the organization for the rest of the manual. Each feature, along with how to set
it up and how to use the outputs is described in complete detail in the later sections of this manual.
I/O Functions
Power System Measurement Functions
The BE1-CDS240 has four sets of three-phase currents that are digitally sampled and digitally
filtered. The fundamental, second, and fifth harmonics are extracted using a Discrete Fourier
Transform (DFT) algorithm for use by all of the current based functions.
Neutral (residual) and negative-sequence current magnitudes are calculated from each set of
three-phase currents.
Each set of three-phase currents can be phase-shifted and tap compensated for use in
transformer differential applications.
Each three-phase current source can have its polarity reversed in the relay, which simplifies the
commissioning process in the event polarity of a CT circuit is rolled.
The digital sampling rate tracks the measured frequency to provide high accuracy at frequencies
other than nominal frequency to make this relay ideally suited for applications such as generator,
motor and generator step-up transformer differential protection.
An independent ground current input (IG) measures the current in a transformer neutral, tertiary
winding or a flux balancing CT and is used for providing ground differential protection.
Each current circuit is low burden and isolated to allow for more effective zoning with fewer costly
CTs.
Three-phase voltage inputs are digitally sampled and the fundamental frequency is extracted
using a Discrete Fourier Transform (DFT) algorithm. Voltage sensing circuits can be configured
for single-phase, three wire or four wire voltage transformer circuits.
Voltage sensing circuitry provides voltage protection, frequency protection, and watt/var
metering. Neutral (residual), positive, negative, and zero sequence voltage magnitudes are
calculated from the three-phase voltages.
Contact Sensing Inputs
Eight (I/O option E) or 12 (I/O option A) programmable contact sensing inputs with programmable
signal conditioning provide binary logic interface to the protection and control system.
The function of each input is programmable using BESTlogic and can be given a user meaningful
name for the variable and for each state (open and closed) for use in reporting functions.
The threshold voltage is adjustable. See Section 12, Installation, Contact Sensing Input Jumpers.
Contact Outputs
Fourteen (I/O option E) or 10 (I/O option A) programmable contact outputs provide a binary logic
interface to the protection and control system (OUT1 through 14). OUTA is dedicated to critical
alarms.
OUT1 and 2 are dedicated form “c” contacts. The remainders are “a” contacts. Outputs 7, 8, 9, 10
are dedicated to trip coil monitoring for up to 4 breakers. However, board level jumpers are
supplied so that the user can disable the TCM circuit and allocate the output contact to any virtual
output. Refer to Section 12, Installation, Trip Coil Monitor (TCM) Jumpers.

9365200990 Rev F BE1-CDS240 General Information 1-3
Each output is programmable using BESTlogic (assign any virtual output to any physical output
relay) and can be given a user meaningful name for the variable and for each state (open and
closed) for use in reporting functions.
Output logic can be overridden to open, close or pulse each output contact for testing, or control
purposes.
Protection and Control Functions
Setting Groups
Four (4) settings groups allow adaptive relaying to be implemented to optimize the relay settings
for various operating conditions.
Automatic and external logic can be employed to select the active setting group.
Differential Protection
Three-phase percentage restrained differential protection with harmonic restraint: 87. Protection
can be set to monitor two, three, or four windings. Unused inputs can be used for overcurrent
protection.
Two restricted earth fault ground differential protection elements with independent ground (IG)
input (and C-phase, IG2, of Current Circuit 4): 87ND and 187ND.
Tap compensation for the differential protection can be automatically calculated by the relay
based upon user settings of CT ratio, MVA and kV base values.
Ground differential between calculated residual of any winding and the phase C current input of a
fourth and unused winding (IG2).
Each winding can be independently set for a phase relationship (relative to winding 1) of 0 to 360
degrees in steps of 30 degrees.
Each winding can be set for IEC standard transformer connections.
Overcurrent Protection
Instantaneous overcurrent with settable time delay for each operating quantity (A, B, C, N (using
IN or IG) and Q. Eight (8) sets Phase, Five (5) sets Neutral, Four (4) sets Negative-Sequence.
Each function is individually assignable to any of the current input circuits. Functions are: 50TP,
150TP, 250TP, 350TP, 450TP, 550TP, 650TP, 750TP, 50TN, 150TN, 250TN, 350TN, 450TN,
50TQ, 150TQ, 250TQ, and 350TQ.
Inverse time overcurrent functions with integrating or instantaneous reset. Four (4) for Phase, five
(5) for Neutral, and four (4) for Negative-Sequence. Each function is individually assignable to
any of the current input circuits. Functions are 51TP, 151TP, 251TP, 351TP, 51TN, 151TN,
251TN, 351TN, 451TN, 51TQ, 151TQ, 251TQ, and 351TQ.
Time overcurrent functions employ a dynamic integrating timing algorithm covering a range from
pickup to 40 times pickup with selectable instantaneous or integrated reset characteristics.
Time overcurrent curves conform to IEEE PC37.112 and include seven curves similar to
Westinghouse/ABB CO curves, five curves similar to GE IAC curves, four IEC curves, a fixed
time curve, and a user programmable curve.
Digital signal processing filters out unwanted harmonic components while providing fast
overcurrent response with limited transient overreach and overtravel.
Voltage Protection
Voltage control or restraint for 51P (51V protection)
One (1) volts per hertz protective element (24) provides overexcitation protection for a generator
and/or transformer.
Two phase (2) undervoltage elements, 27P and 127P, provide phase undervoltage protection.
Two phase (2) overvoltage elements, 59 and 159, provide phase overvoltage protection.
One (1) negative-sequence overvoltage element (47) provides protection for phase unbalance or
a reverse system phase-sequence.
One (1) zero sequence overvoltage element (59X) provides protection for ground faults on
ungrounded systems using calculated 3VO.
Frequency Protection
Six (6) over/underfrequency protection elements are provided: 81, 181, 281, 381, 481, and 581.

1-4 BE1-CDS240 General Information 9365200990 Rev F
Fuse Loss Protection
A fuse loss function, 60FL, protects against false tripping due to a loss of voltage sensing.
Breaker Failure Protection
Four (4) breaker failure protection function blocks are assignable to any of the current input
circuits: 50BF, 150BF, 250BF, and 350BF.
The current circuit assigned to the breaker failure function block also determines which current
circuit is used by the breaker monitoring functions described later.
General Purpose Logic Timers
Four (4) general-purpose logic timers with six modes of operation: 62, 162, 262, and 362.
Virtual Control Switches
Four (4) virtual breaker control switch, accessible locally from the HMI or remotely from the
communications ports can be used to provide trip and close control of a selected breaker: 101,
101A, 101B, and 101C.
The breaker label provided for the breaker monitoring function is used to label the virtual breaker
control switch. This makes it easily discernible which breaker is being controlled as up to four (4)
breakers can be controlled.
Eight virtual switches with three modes of operation, accessible locally from the HMI or remotely
from the communications ports. Switches can be used to provide additional control: for example,
to trip and close additional switches or breakers, or to enable and disable certain functions: 43,
143, 243, 343, 443, 543, 643, and 743.
Metering Functions
Metering, including magnitude and angle, is provided for all measured phase and neutral voltage
and currents and all derived positive, neutral, and negative-sequence voltage and currents.
Power factor, frequency, watts, vars, and demands are also provided.
Metering, including magnitude and angle, is also provided for the phase and tap compensated
restraint, second and fifth harmonic, and differential currents.
Reporting and Alarm Functions
Relay Identification
The relay includes four 30-character, free-form fields for the user to enter information to identify
the relay. Examples would be station name, circuit number, relay system, purchase order, etc.
These fields are used by many of the reporting functions to identify which relay created the report.
Clock
A real-time clock is included with a capacitor backup that will keep time upon loss of power for 8
to 24 hours depending upon conditions. Optional battery backup maintains time keeping for an
extended period.
A standard IRIG input (format B002 from IRIG Standard 200-98) is provided for receiving time
synchronism signals from a master clock.
The time and date reporting format is settable for 12 or 24-hour format and for mm/dd/yy or
dd/mm/yy format.
Automatic daylight savings time adjustment can be enabled.
General Status Reporting
The relay has extensive capability to report its general status for monitoring, commissioning, and
troubleshooting.
Status reports are available from the HMI or the communications ports.
Demand Reporting
Ampere demand registers are provided for monitoring A, B, C, N, and Q. These registers are
assignable to any of the current input circuits.
The demand interval and demand calculation method is separately settable for phase, neutral
and negative-sequence measurements.

9365200990 Rev F BE1-CDS240 General Information 1-5
The demand reporting function records today's peak, yesterday's peak, and peak since reset,
with time stamps for each register.
An optional 4,000-point data array can record over 40 days of 15-minute demand data.
Differential Current Monitoring
A detailed current check record can be requested from the relay to aid in initial in-service
readings to verify correct phase and tap compensation of the differential currents. This report can
be stored with commissioning records to save time during initial check out.
Once in service, the mismatch in the differential function is continuously monitored and can
provide an alarm if the mismatch is approaching a trip condition due to loading current. A current
check record is generated when this occurs and the diagnostic function will indicated the possible
source of the mismatch: for example, incorrect or missing phase compensation.
Transformer Monitoring
Transformer through-fault duty statistics are recorded including number of through faults,
accumulated through-fault (It or I2t), and maximum through-fault (It or I2t). The through-fault
current measurement is assignable to any of the current input circuits.
Each of these conditions can be set to alarm.
Breaker Monitoring
Breaker statistics are recorded for up to four breakers. They include the number of operations,
fault current accumulation duty and breaker time to trip. This function is associated with the
current input circuit assigned to the breaker failure function block.
Each of these conditions can be set to alarm.
Trip Circuit Monitoring
Four trip circuit monitor functions are provided to monitor the trip circuit of a breaker or lockout
relay for loss of voltage (fuse blown) or loss of continuity (trip coil open).
Each of the four TCMs can be disabled with a circuit board jumper allowing the associated output
to operate the same as the other outputs.
Fault Reporting
Fault reports consist of simple target information, fault summary reports, and detailed
oscillography records to enable the user to retrieve information about disturbances in as much
detail as is desired.
Oscillography memory can be partitioned into 6 to 16 records and all data is stored in non-volatile
memory.
The relay records and reports oscillography data in industry standard IEEE, COMTRADE format
to allow using any fault analysis software.
Sequence Of Events Recorder
A 255-event sequence of events recorder (SER) is provided that records and time stamps all
inputs and outputs to the relay as well as all alarm conditions monitored by the relay. Time
stamps are to the nearest quarter cycle resolution. All records are stored in non-volatile memory.
I/O and Alarm reports can be extracted from the records as well as reports of events recorded
during the time span associated with a specific fault report.
Alarm Function
The relay includes extensive self-diagnostics. Fatal relay trouble alarms are not programmable
and are dedicated to the alarm output (OUTA) and the relay trouble LED on the front of the relay.
Additional relay trouble alarms and all other alarm functions are programmable for major or minor
priority. Programmed alarms are indicated by major and minor alarm LEDs on the front of the
relay. The major and minor alarm points can also be programmed to any output contact including
OUTA.
The HMI provides local annunciation of programmed alarm conditions.
Active alarms can be read and reset from the optional HMI or from the communications ports.
Seventy (70) alarm conditions are available to be monitored including user definable logic
conditions using BESTlogic.

1-6 BE1-CDS240 General Information 9365200990 Rev F
Version Report
The version of the embedded software (firmware) is available from the front panel interface HMI
or the communications ports.
The unit serial number and style number is also available from the communications ports.
BESTlogic Programmable Logic
Each of the protection and control functions in the BE1-CDS240 is implemented in an
independent function that is equivalent to its single function, discrete device counterpart so that it
is immediately familiar to the protection engineer. Each independent function block has all of the
inputs and outputs that the discrete component counterpart might have.
Programming BESTlogic is equivalent to choosing the devices required by your protection and
control scheme and drawing schematic diagrams to connect the inputs and outputs to obtain the
desired operational logic.
One preprogrammed embedded logic scheme (in the relay firmware) and a library of
preprogrammed logic schemes in BESTCOMS are provided and thoroughly documented in
Section 8, Applications. To set the relay to one of the BESTCOMS library applications, simply
select the logic scheme and upload it to the relay.
A set of custom logic settings is also available for you to optimize the functionality to the specific
needs of your operation's practices and power system requirements.
Security
Security can be defined for three distinct functional access areas: Settings, Reports, and Control.
Each functional access area can be assigned a password. A global password provides access to
all three functional areas. Each of these four passwords can be unique or multiple functional
access areas can have the same password.
Allowing the user to restrict access to any of the three functional access areas from only specific
communication ports provides a second dimension of security. For example, you could set
security to deny access to control commands from the rear RS-232 port that is connected through
a modem to a telephone line.
Security settings only affect write access. You have read access from any port to any area.
Human-Machine Interface
Each BE1-CDS240 comes with a front panel display with LED (light emitting diode) indicators for
power, relay trouble alarm, minor alarm, major alarm, and trip. Each BE1-CDS240 also comes
with the software application program BESTCOMS for the CDS240. This program is a user
friendly, Windowsbased program that makes relay setup and support very easy.
The programmable graphical LCD (liquid crystal display) allows the relay to replace local
indication and control functions such as panel metering, alarm annunciation, and control
switches.
The human-machine interface (HMI) is set up in a menu tree with four scrolling buttons for
navigation. Edit and Reset pushbuttons provide access to change parameters and reset targets,
alarms and other registers. Scrolling buttons are used for data entry when in edit mode. Edit
mode is indicated by an LED on the Edit button.
The LCD has automatic priority logic to govern what is being displayed on the screen so that
when an operator approaches, the information of most interest is automatically displayed without
having to navigate the menu structure. The priorities are targets, then alarms and then the
programmable automatic scrolling list.
Up to 16 screens can be defined in the programmable, automatic scroll list.
ASCII Command Interface
Three (3) independent, isolated communications ports provide access to all functions in the relay.
Com 0 is a 9-pin RS-232 port located on the front of the case. Com 1 is a 9-pin RS-232 port
located on the back of the case. Com 2 is a three-terminal, RS-485 port located on the back of
the case.
Standard communications is an ASCII command interface to allow easy interaction with the relay
using standard, off the shelf, communications software.

9365200990 Rev F BE1-CDS240 General Information 1-7
The ASCII command interface is optimized to allow automating the procedure for setting the relay
by allowing settings files to be captured from the relay and edited using any software that
supports *.txt file format. These ASCII *.txt files can then be used to set the relay using the send
text file function of the communications software.
Modbus™ and other common protocols are optionally available for the RS-485 communications
port. A separate instruction manual appropriate for the protocol comes with each unit. Consult the
product bulletin or the factory for availability of these options and instruction manuals.
Installation
The BE1-CDS240 is available in two, fully draw-out, case styles; MX vertical can be mounted as
an M1, M2, FT31, or an FT32. MX horizontal units can be panel mounted or 19" rack mounted.
Relay terminals are clearly marked on the rear panel.
Testing and Maintenance
Four (4) testing methods are covered in this manual: acceptance testing, commissioning testing,
periodic testing, and functional testing.
The relay also provides a virtual testing function that allows the user to isolate a portion of the
logic program and test it by using a set of switches.
BESTCOMS Software
BE1-CDS240 BESTCOMS is a 32-bit Windowsbased graphical user interface (GUI). It provides
the user with point-and-click capability for applying settings to the relay. This facilitates setting the
relay by eliminating the need for the user to be thoroughly knowledgeable of the ASCII
commands associated with the relay settings.
PRIMARY APPLICATIONS
The BE1-CDS240 Current Differential System provides percentage restrained differential protection along
with multiple overcurrent elements and is intended for use in any low impedance current differential
protection application including transformer, generator, motor, reactor, and bus protection. Its unique
capabilities make it ideally suited for applications with the following requirements.
Applications that require low burden to extend the linear range of CTs.
Applications where dedicated CTs for the differential are not available. Unlike traditional
differential relays, dedicated CT circuits are not required because each CT input is isolated from
the others and phase shift compensation can be accomplished internally.
Applications that require high accuracy across a wide frequency range such as motor, generator,
and generator step-up transformer protection or in co-generation facilities.
Applications that require the flexibility provided by wide settings ranges, multiple setting groups
and multiple coordination curves in one unit.
Applications that require the economy and space savings provided by a multifunction, multi-phase
unit. This one unit can provide all of the protection, as well as, the local and remote indication,
metering and control required on a typical circuit.
Applications that require harmonic restraint to aid security for the differential.
Applications that require communication capability and protocol support.
Applications where the optional case configurations facilitate modernizing protection and control
systems in existing substations.
Applications where the capabilities of a digital multifunction relay are required, yet draw-out
construction is also desirable.
Applications where bus protection is provided by a high-speed overcurrent-blocking scheme on
the transformer bus mains instead of dedicated bus differential circuit.
Applications where the capabilities of intelligent electronic devices (IEDs) are used to decrease
relay and equipment maintenance costs.

DIFFERENTIAL PROTECTION APPLICATION CONSIDERATIONS
The principle of current differential relaying is simple in concept. Measure the current flowing into the
protected zone and the current flowing out of the protected zone. These should match exactly (sum to
zero). If they do not, there is a fault within the protected zone. The mismatch in current that results from
the instantaneous summation of the currents into and out of the zone of protection is called the differential
current or the operate current. While the concept is simple, several difficulties present challenges to the
application of this type of protection. The BE1-CDS240 Current Differential System provides several
features that allow it to easily address these complications and enable it to be used in all differential
applications including transformer protection.
Problem 1: False Differential Current Due to Poor CT Performance
General
The principle of current differential relaying requires accurate measurement of the currents entering and
exiting the zone of protection. During fault conditions where high current is flowing through the zone of
protection, a CT may saturate and not faithfully reproduce the current flowing in the primary system. This
will cause a false differential current to be seen by the differential relay.
BE1-CDS240 Solution
The percentage restrained differential characteristic, shown in Figure 1-1, is applied in this application.
The differential current required to cause a trip is a percentage of the restraint current. The restraint
current is a measure of the current flowing into or through the zone of protection. Thus for higher levels of
restraint current, where the CTs may be subject to saturation, higher levels of differential current must be
seen to cause a trip. The percentage restraint is often called the slope characteristic.
Figure 1-1. Restrained Differential Characteristic
The BE1-CDS240 relay has two settable restraint current calculation methods: average and maximum.
Average restraint emulates the operating characteristics of common electromechanical relays. Maximum
restraint is recommended because it uses the current from the best performing CT to determine the
restraint to use during a fault condition. In addition, digital technology provides a transient monitor
function that enables the BE1-CDS240 relay to detect the onset of CT saturation to ride through the
condition to further enhance security from misoperation caused by poorly performing CTs.
Finally, Basler Electric addresses the source of false differential current at its roots. Active CT technology
used on the current inputs provides low burden to extend the linear range of power system CTs and wide
dynamic range to reduce measurement errors at high current levels. Sixteen bit ADC performance and
digital anti-aliasing filters also contribute to minimizing magnitude and angle measurement errors.
1-8 BE1-CDS240 General Information 9365200990 Rev F

Problem 2: Measured Current Magnitude Mismatch
General
The currents measured by each set of current inputs can be transformed from their primary values by
different CT ratios. This is illustrated in Figure 1-2. When the zone of protection includes a transformer,
there is another source of magnitude mismatch that must be accounted for. The primary currents that the
differential relay must monitor will be on different voltage bases in most cases. This is due to the
transformer action; the current on each side of the transformer is transformed by the inverse of the
voltage transformation ratio. This is illustrated in Figure 1-3.
BE1-CDS240 Solution
The BE1-CDS240 relay applies a tap adjustment factor to the measured currents to cancel the effect of
dissimilar CT ratio and voltage bases by converting the currents to per unit quantities on a common base.
The tap-adjusted currents are used by the percentage restrained differential protection functions to
determine the restraint and differential currents. Thus, the mismatch in magnitudes under normal
balanced conditions is eliminated. The tap adjustment factor can be manually entered or automatically
calculated by the relay using parameters entered for each CT input circuit and for the differential tap
settings.
The setup parameters for each of the current input circuits are described in Section 3, Input and Output
Functions, Power System Inputs. The CT ratio is included to allow the currents to be metered, displayed,
and reported in primary values. The CT ratio is also used as a parameter for the automatic tap calculation
feature.
D2837-18
12-14-98
600:5
400A
600:5
400A
600:5
400A
CDS
1200:5
1200A
5.0 A
Secondary
10.0 A
Secondary
Input 1 Tap = 5
Input 2 Tap = 10
So 5A = 1 x Tap
10A = 1 x Tap
Current-out balances current-in (in multiples of tap).
9365200990 Rev F BE1-CDS240 General Information 1-9
40A
D2837-17.vsd
12-14-98
2400/240 Volts
H
1
H
0
400A
X
1
X
0
Figure 1-2. Tap Adjust for Mismatch Figure 1-3. Currents on Different
Voltage Bases
The setup parameters for the tap adjustment factor are described in Section 4, Protection and Control,
Differential Protection. The user can enter the megavolt ampere (MVA) base for the application and the
kilovolt (kV) base for each current input and the relay will automatically calculate the taps using these
settings and the settings for each current input circuit. Alternatively, the user can enter the taps directly for
each CT input.
Problem 3: Mismatch Caused by Load Tap Changers
General
The voltage transformation ratio (and thus the current transformation ratio) of a transformer within the
zone of the differential can be adjusted in service by typically ±10% with the use of load tap changers.

1-10 BE1-CDS240 General Information 9365200990 Rev F
The tap adjustment factors can be used to eliminate the mismatch when the tap changer is at neutral.
But, when the tap changer is off of neutral, differential current will be measured.
BE1-CDS240 Solution
The percentage restraint characteristic of the differential function mentioned previously allows the relay to
accommodate a prescribed amount of mismatch. The differential current must exceed a percentage of the
through current as described by the slope characteristic setting of the differential protection function. Also,
the relay has four setting groups to allow the tap settings and other parameters to be changed
dynamically based upon operating conditions.
Problem 4: Phase Angle Shift
General
When differential protection is used in a transformer application, the transformer often introduces a phase
shift between the various current inputs to the zone of protection. An example is a transformer with a
delta- connected high side and a wye-connected low side as shown in Figure 1-4, Illustration A. The
currents in the phases connected to the delta side of the transformer are each made up of the
combination of the current flowing in two legs of the delta winding. On the other hand, the currents in the
phases connected to the wye side of the transformer are made up of the current in only one leg of the
wye winding. It can be seen that the primary currents flowing into the zone of protection when tap is
adjusted for magnitude mismatch still do not sum to zero as shown in Figure 1-4, Illustrations B and C.