Basler BE1-CDS220 User manual

INSTRUCTION MANUAL
FOR
CURRENT DIFFERENTIAL SYSTEM
BE1-CDS220
D2857-19
08-18-00
Publication: 9313900990
Revision: B 01/06

BE1-CDS220 Introduction i
INTRODUCTION
This instruction manual provides information about the operation and installation of the BE1-CDS220
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 inputs and outputs, 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.
•Description of BESTCOMS graphical user interface (GUI).
•Appendices containing time overcurrent characteristic curves, an ASCII command-HMI cross
reference, terminal communications, and settings calculations.
WARNING!
TO AVOID PERSONAL INJURY OR EQUIPMENT DAMAGE, ONLY QUALIFIED
PERSONNEL SHOULD PERFORM THE PROCEDURES PRESENTED 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.

ii Introduction BE1-CDS220
First Printing November 1999
Printed in USA
© 1999, 2000, 2006 Basler Electric, Highland, Illinois 62249 USA
All Rights Reserved
January 2006
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 Company, Highland, Illinois.
BASLER ELECTRIC
ROUTE 143, BOX 269
HIGHLAND, IL 62249 USA
http://www.basler.com, [email protected]
PHONE [phone] FAX [phone]
CONFIDENTIAL INFORMATION
OF BASLER ELECTRIC COMPANY, HIGHLAND, IL. 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 COMPANY.

BE1-CDS220 Introduction iii
PRODUCT REVISION HISTORY
The following information provides a historical summary of the changes made to the software, embedded
software (firmware), and hardware of this device. The corresponding revisions made to this instruction
manual are also summarized. This revision history is separated into four categories: BESTCOMS
Software, Application Program Firmware Version, Hardware Version, and Manual Revision. All revisions
are listed (with the month and year) in reverse chronological order with the most recent on top.
BESTCOMS
Software
Version/Date Change
2.01.00/07-05 Improved ability to use special characters in comments.
Enhanced program to work with RS232 converters.
Corrected printout problem with long comments.
Added “Settings Compare” feature.
2.00.01/10-02 Initial 32-bit release.
Improved the 87ND function block diagram.
Corrected tap calculation reporting errors.
Improved programming of Reset Target Logic.
Corrected the SG-COM2 command to be sent out correctly.
1.01.01/12-99 Added ability to create, upload, and download settings files.
Added ability to read fault report directory and fault summary reports.
Improved communications.
1.01.00/05-99 Initial 16-bit release.
Application
Program
Firmware
Version/Date Change
1.15.00/01-06 Minor software enhancements.
1.14.10/11-05 Removed write capability from some Modbusregisters.
1.14.09/07-05 Improved LCD display.
1.14.08/09-03 Added diagnostics for in-house testing.
1.14.07/08-03 Corrected the harmonic sharing inhibit problem.
Enhanced breaker operations counter.
Corrected cal defaults loaded problem when upgrading firmware.

iv Introduction BE1-CDS220
Application
Program
Firmware
Version/Date Change
1.14.05/06-03 Corrected ND timer problem.
Enhanced in-house diagnostics.
1.14.04/10-02 Corrected triggering problem of 2nd oscillography record.
Allowed the differential alarm to be disabled through SA-DIFF serial command.
Improved SER most recent events reporting.
Improved 62 timer function.
Corrected help text for SG-TARG command.
Allowed Trip Led to turn off when current is removed and SG-TARG=0.
Updated 87ND time delay settings.
Correctly improper display of Q demand on LCD.
Moved the degree symbol to the proper location on the LCD for the GND
current.
Improved 50TQ and 51Q time delay functions.
1.14.03/06-01 Fixed the SG-DI command (Setting Group-Demand Interval) so that it now
recognizes a demand interval of three or more digits as being “out of range”.
Added improvements to DNP 3.0, Level 2 protocol.
Added new “Password Security” parameters to Modbus protocol.
Modified display of Phase Angle information (HMI and reports) so that an
asterisk (∗) appears in the angle position if the measured current is below 1%
of rated current (0.05 A for a 5 A relay, 0.01 A for a 1 A relay).
1.14.02/05-01 Corrected firmware problems with Modbus and DNP protocols.
1.14.01/09-00 Added reporting of the protocol option to the COM2 setting screen on the LCD
HMI.
Improved the arrangement of information on the current metering screens on
the HMI.
Added improvements to DNP 3.0 protocol to make it Level 2 compliant.
1.14.00/03-00 Corrected problem that caused the programmable variable names to be limited
to 10 characters instead of 16 characters. This problem occurred with version
1.13.01.
Added Mode 6, Latching Timer to 62 timer functions.
Added DNP 3.0 Protocol.
Added a feature for the demand recording function to allow the user to select
block average or sliding block average calculation method in addition to the
existing thermal calculation method.

BE1-CDS220 Introduction v
Application
Program
Firmware
Version/Date Change
1.13.01/11-99 Added option to select Percent of Average Restraint Current operating
characteristic to the 87R, Percentage Restrained Differential element.
Added Modbus protocol option.
Improved COMTRADE oscillography recording function as follows:
•Provided user setting to partition the 240 cycles of oscillography memory to
provide control over the length of the records.
•Doubled available oscillography memory to 480 cycles when enhanced
recording option is present.
•Added ∗.hdr file in addition to the two files required by the COMTRADE
standard (∗.cfg and ∗.dat) to provide additional information useful in
analyzing the data contained in the oscillographic record.
Improved target reporting function such that the Trip LED on the relay front
panel only latches when there are targets to be displayed on the HMI. The
pickup condition, indicated by the Trip LED flashing, is now a higher priority
than latching to indicate that targets are being displayed on the HMI.
Corrected problem with the 51 inverse overcurrent timing algorithm that could
cause an element to time out too fast when using the V2 curve.
1.12.01/06-99 Improved current check record diagnostic routine.
Corrected problem that caused magnitude in several reporting functions to be
reported in primary amps squared.
Changed several setting defaults.
1.12.00/04-99 Initial release.
Hardware
Version/Date Change
T/08-05 Upgraded U55 on main board to improve LCD.
S/06-05 Improved CT terminal block.
R/01-03 Improved RS-485 communications when slow baud rates are used.
Improved front panel display.
P/05-02 Added labeling to back of case.
Added RTV to ‘s’ wire of T1 to prevent hipot failure.
N/06-01 Improved low-frequency filtering on LCD.
M/03-01 Relocated P2 on magnetics board.

vi Introduction BE1-CDS220
Hardware
Version/Date Change
L/03-01 Changed clearance around Q3 on power supply to prevent shorts.
K/09-00 Improved Surge Withstand Capability.
J/09-00 Improved the RS-485 operation when driving long lines.
I/08-00 Added CE qualification, UL recognition, and CSA certification.
H/08-00 Changed escutcheon plate from mounting holes to mounting studs.
G/04-99 Initial release.
Manual
Revision/Date Change
B/01-06 Added Section 14, BESTCOMS Software.
Re-organized Section 12, Installation.
Added Power System Application Figures 12-26 and 12-27.
A/09-00 Changed the manual organization from two volumes to one volume in a loose
leaf binder with tabs to separate the manual sections.
Added Revision History to the Introduction, and CE qualification, UL
recognition, CSA certification, and DNP 3.0 certification.
Added drawings and minor corrections to all sections.
−/11-99 Initial release.

BE1-CDS220 Introduction vii
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 Command Cross-Reference ..............................................................B-1
APPENDIX C Terminal Communications..................................................................C-1
APPENDIX D Settings Calculations..........................................................................D-1

viii Introduction BE1-CDS220
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BE1-CDS220 General Information i
SECTION 1 •GENERAL INFORMATION
TABLE OF CONTENTS
DESCRIPTION......................................................................................................................................1-1
FEATURES............................................................................................................................................1-1
Input and Output Functions...............................................................................................................1-1
Protection and Control Functions......................................................................................................1-2
Metering ............................................................................................................................................1-3
Reporting and Alarm Functions.........................................................................................................1-3
BESTlogic Programmable Logic.......................................................................................................1-4
Security .............................................................................................................................................1-5
Human-Machine Interface.................................................................................................................1-5
ASCII Command Interface ................................................................................................................1-5
PRIMARY APPLICATIONS...................................................................................................................1-6
DIFFERENTIAL PROTECTION APPLICATION CONSIDERATIONS..................................................1-6
Problem 1: False Differential Current Due to Poor CT Performance................................................1-6
Problem 2: Measured Current Magnitude Mismatch ........................................................................1-7
Problem 3: Mismatch Caused by Load Tap Changers.....................................................................1-8
Problem 4: Phase Angle Shift ...........................................................................................................1-9
Problem 5: Zero Sequence Current Sources within the Zone Of Protection..................................1-12
Problem 6: Transformer Energization Inrush and Overexcitation...................................................1-13
Problem 7: Digital Measurement Errors..........................................................................................1-14
MODEL AND STYLE NUMBER DESCRIPTION ................................................................................1-14
General............................................................................................................................................1-14
Sample Style Number .....................................................................................................................1-15
OPERATIONAL SPECIFICATIONS....................................................................................................1-15
Metered Current..............................................................................................................................1-15
Metered Frequency.........................................................................................................................1-15
Calculated Values and Accuracy ....................................................................................................1-16
Real-Time Clock..............................................................................................................................1-16
IRIG.................................................................................................................................................1-16
Contact Inputs .................................................................................................................................1-16
87 Differential Functions .................................................................................................................1-16
87ND Neutral Differential Function .................................................................................................1-17
Time Overcurrent Functions............................................................................................................1-18
Time Current Characteristic Curves................................................................................................1-18
Instantaneous Overcurrent Functions.............................................................................................1-18
Breaker Failure (BF)........................................................................................................................1-19
General Purpose Timers (62, 162)..................................................................................................1-19
Automatic Setting Group Characteristics........................................................................................1-19
BESTlogic........................................................................................................................................1-20
GENERAL SPECIFICATIONS ............................................................................................................1-20
AC Current Inputs............................................................................................................................1-20
Analog to Digital Converter .............................................................................................................1-20
Power Supply ..................................................................................................................................1-20
Output Contacts ..............................................................................................................................1-20
Control Inputs..................................................................................................................................1-20
Communication Ports......................................................................................................................1-21
Display.............................................................................................................................................1-21
Isolation...........................................................................................................................................1-21
Surge Withstand Capability.............................................................................................................1-21
Radio Frequency Interference (RFI) ...............................................................................................1-21
Electrostatic Discharge (ESD).........................................................................................................1-21
UL Recognition................................................................................................................................1-21
C.S.A. Certification..........................................................................................................................1-22
CE Qualified....................................................................................................................................1-22
GOST-R Certification ......................................................................................................................1-22
DNP Certification.............................................................................................................................1-22

ii General Information BE1-CDS220
Environment ....................................................................................................................................1-22
Shock...............................................................................................................................................1-22
Vibration ..........................................................................................................................................1-22
Weight .............................................................................................................................................1-22
Case Configurations........................................................................................................................1-22
Figures
Figure 1-1. Restrained Differential Characteristic......................................................................................1-7
Figure 1-2. Tap Adjust For Mismatch ........................................................................................................1-8
Figure 1-3. Currents on Different Voltage Bases.......................................................................................1-8
Figure 1-4. Delta/Wye Transformer Currents ..........................................................................................1-10
Figure 1-5. Three-Phase Connections, Delta-Wye Configuration, CT Compensation............................1-11
Figure 1-6. Three-Phase Connections, Delta-Wye Configuration, Internal Phase Compensation .........1-11
Figure 1-7. Traditional Zero-Sequence Trap for Application with Ground Banks....................................1-13
Figure 1-8. Style Number Identification Chart..........................................................................................1-15
Figure 1-9. Typical 87 Response Characteristic Curves .........................................................................1-17
Tables
Table 1-1. Control Input Burden...............................................................................................................1-21

BE1-CDS220 General Information 1-1
SECTION 1 •GENERAL INFORMATION
DESCRIPTION
The BE1-CDS220 Current Differential System is an economical, microprocessor based, multifunction
system that provides two-input, three-phase percentage differential with harmonic restraint, three-phase,
ground, and negative sequence overcurrent protection with control, breaker failure, breaker monitoring,
transformer monitoring, and metering functions in an integrated system with communications. The
BE1-CDS 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.
BE1-CDS relays have eight programmable contact sensing inputs, six programmable outputs, and one
alarm output. Outputs can be assigned various functions by logical programming to perform protection,
control, or indicator operations. For example, protection functions could cause a protective trip operation.
Control functions could cause a manual trip, manual close or automatic reclose operation. Indicators
could be relay fail, setting group one enable, setting group two enable, and others.
Protection scheme designers may select from a number of pre-programmed logic schemes that perform
the most common protection and control requirements or create a custom scheme using BESTlogic.
A Quick Start, Section 2, provides BE1-CDS Current Differential System users with a simplified How to
Get Started procedure.
FEATURES
The BE1-CDS220 relay 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, and reporting and alarm functions. 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 optional advanced HMI (Human Machine
Interface) provide easy access to the features provided. BE1-CDS220 relay users with personal
computers (PC) have another easy access means to communicate, program, control, and monitor
relay/system performance. That means is BESTCOMS for BE1-CDS220. BESTCOMS is a Windows
based software application that enhances communication between the PC user and the BE1-CDS220
relay. This software is provided free with every BE1-CDS220 relay. Another software application tool is
BESTWAVE. BESTWAVE is a utility program to view standard COMTRADE (Common Format for
Transient Data Exchange) files and Basler UMOS (Utilities Management Operating System) files captured
by the Basler Electric multifunction relays. This software is available free of charge through the web site at
http://www.basler.com or Customer Service at the Highland, Illinois manufacturing facility.
The following information summarizes the features included in this multifunction device. The organization
of this information outlines organization of 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.
Input and Output Functions
Power System Measurement Functions
•Two sets of three-phase currents 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 derived from each set of three-
phase currents.
•Each set of three-phase currents can be phase-shift and tap compensated for use in transformer
differential applications.
•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.

1-2 General Information BE1-CDS220
•An optional independent ground current input is available for directly measuring the current in a
transformer neutral, tertiary winding, or a flux balancing CT and for providing ground differential
protection.
•Each of the seven current sensing circuits is low burden and isolated to allow improving zones of
protection with fewer costly CTs.
Contact Sensing Inputs
•Eight programmable contact sensing inputs with programmable signal conditioning provide binary
logic interface to the protection and control system: IN1, IN2, IN3, IN4, IN5, IN6, IN7, and IN8.
•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.
Contact Outputs
•Six programmable general purpose contact outputs provide binary logic interface to the protection
and control system: OUT1, OUT2, OUT3, OUT4, OUT5, and OUT6.
•One programmable, fail-safe, alarm output: OUTA
•All outputs are trip rated and output 1 and 6 are high speed (quarter-cycle nominal speed). Output
6 is Form C.
•Each output 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.
•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 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.
•Restricted earth fault ground differential protection with optional independent ground input: 87ND.
•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.
Overcurrent Protection
•Nine instantaneous overcurrent functions with settable time delay. Three each for Phase, Neutral,
and Negative Sequence. Each function is individually assignable to any of the current input
circuits. Functions are: 50TP, 150TP, 250TP, 50TN, 150TN, 250TN, 50TQ, 150TQ, 250TQ.
•Nine inverse time overcurrent functions with integrating or instantaneous reset. Three each for
Phase, Neutral, and Negative Sequence. Each function is individually assignable to any of the
current input circuits. Functions are: 51TP, 151TP, 251TP, 51TN, 151TN, 251TN, 51TQ, 151TQ,
251TQ.
•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 the IEEE PC37.112 document 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.
Breaker Failure Protection
•One breaker failure protection function block is assignable to any of the current input circuits.
•The current circuit assigned to the breaker failure function block also determines which current
circuit is used by the breaker monitoring functions described later.

BE1-CDS220 General Information 1-3
General Purpose Logic Timers
•Two general purpose logic timers with six modes of operation: 62, 162.
Virtual Control Switches
•One virtual breaker control switch, accessible locally from the optional HMI or remotely from the
communications ports, can be used to provide trip and close control of a selected breaker: 101.
•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 since there is
often more than one breaker associated with the differential zone of protection.
•Eight virtual switches with three modes of operation, accessible locally from the optional HMI or
remotely from the communications ports, can be used to provide additional control; for example,
to trip and close additional switches or breakers, or to enable and disable certain functions such
as 43, 143, 243, 343, 443, 543, 643, 743.
Metering
•Metering is provided for all measured phase and neutral currents and all derived neutral and
negative sequence currents.
•Metering is also provided for the phase and tap compensated restraint, 2nd and 5th 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.
•A standard IRIG input (Format B002 from IRIG Standard 200-98) is provided for receiving time
synch signals from a master clock.
•The time 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
trouble shooting.
•Status reports are available from the optional 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.
•The demand reporting function records today’s peak, yesterday’s peak, and peak since reset with
time stamps for each register.
•An optional 4000 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 indicate the possible
source of the mismatch: for example, incorrect or missing phase compensation.

1-4 General Information BE1-CDS220
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 a single breaker. They include the number of operations,
accumulated interrupted Ior I2, 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
•A trip circuit monitor function is 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).
•Additional trip or close circuit monitors can be implemented in BESTlogic using additional inputs,
logic timers, and programmable logic alarms.
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 (6 to 32 records with enhanced
recording option, Load Profile option Y).
•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.
•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 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 optional HMI provides local annunciation of programmed alarm conditions.
•Active alarms can be read and reset from the optional HMI or from the communications ports. A
historical sequence of events report of alarms with time stamps as to when each alarm occurred
and cleared is also available from the communications ports.
•Twenty-eight alarm conditions are available to be monitored including user definable logic
conditions using BESTlogic.
Version Report
•The version of the embedded software (firmware) is available from the optional 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-CDS 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

BE1-CDS220 General Information 1-5
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.
•Several preprogrammed logic schemes are provided and thoroughly documented in this manual
in Section 8, Applications. To use the relay in one of these applications, it is only necessary to
make that scheme active.
•A set of custom logic settings is also available for you to optimize the functionality to the specific
needs of your operations 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 can provide access
to all three functional areas. Each of these four passwords can be unique or multiple functional
access areas can have the same password.
•A second dimension of security is provided by allowing the user to restrict access to any of the
three functional access areas from only specific communication ports. 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-CDS220 comes with a front panel display with LED indicators for power, relay trouble
alarm, minor alarm, major alarm, and trip. Each BE1-CDS also comes with the software
application program BESTCOMS-CDS220-16. This program is a user friendly, Windows® based
program that makes relay setup and support very easy.
•The optional programmable graphical LCD allows the relay to replace local indication and control
functions such as panel metering, alarm annunciation, and control switches.
•The 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.
The scrolling buttons are used for data entry when in edit mode. Edit mode is indicated by an Edit
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, then the
programmable automatic scrolling list.
•Up to 16 screens can be defined in the programmable automatic scroll list.
ASCII Command Interface
•Three 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 nine pin RS-232 port
located on the back of the case. Com 2 is a 3-wire, 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.
•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.

1-6 General Information BE1-CDS220
PRIMARY APPLICATIONS
The BE1-CDS 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 cogeneration 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, multiphase
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 drawout
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, differential protection has several difficulties
which present challenges to the application of this type of protection. The BE1-CDS 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-CDS 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.

BE1-CDS220 General Information 1-7
1234
123
OPERATINGCURRENT(INMULTIPLESOFTAP)
MAXIMUM RESTRAINT CURRENT (IN MULTIPLES OF TAP)
D2837-11.DWG
01-05-99
SLOPE=
MINIMUM PICKUP
= 0.01 to 1.00
TIMES TAP
5
I
I
RESTR
OP
*100=(15TO60%)
Figure 1-1. Restrained Differential Characteristic
The BE1-CDS 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-CDS 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.
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. That is—due to the trans-
former 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.

1-8 General Information BE1-CDS220
D2837-18.dwg
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).
Figure 1-2. Tap Adjust For Mismatch
40A
D2837-17.vsd
12-14-98
2400/240 Volts
H
1
H
0
400A
X
1
X
0
Figure 1-3. Currents on Different Voltage Bases
BE1-CDS220 Solution:
The BE1-CDS220 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 Measurement Functions. 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.
The setup parameters for the tap adjustment factor are described in Section 4, Protection and Control
Functions, 87 Differential Protection. The user can enter the mega-volt-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. Or, the user can enter the taps
directly for each CT input.
Problem 3: Mismatch Caused by Load Tap Changers
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.
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.