Basler Electric DECS-250N User Manual

INSTRUCTION MANUA L

FOR

DECS-250N

Digital Excitation Control System

Publication: 9440500990
Revision: D May-15

9440500990 Rev D i

Caution

Note

Note

Be sure that the device is hard-wired to earth groun d with no smaller

with local codes and conventions.

Preface

This instruction manual provides information about the installation and operation of the DECS-250N
Digital Excitation Control System. To accomplish this, the following information is provided:

• General Information

• Human-machine interface

• Functional description

• Installation

• BESTCOMSPlus

• Setup

• Communication protocols

• Maintenance

• Specifications

• Expansion modules

Conventions Used in this Ma nua l

Important safety and procedural information is emphasized and presented in this manual through
warning, caution, and note boxes. Each type is illustrated and defined as follows.

®

software

Warning!

Warning boxes call attention to conditions or actions that may cause
personal injury or death.

Caution boxes call attention to operating conditions that may lead to
equipment or property damage.

Note boxes emphasize important information pertaining to installation
or operation.

than 12 AWG (3.3 mm2) copper wire attached to the case ground
terminal. When the device is configured in a system with other
devices, a separate lead should be connected from the ground bus to
each device.

Current transformer (CT) grounding should be applied in accordance

DECS-250N Preface

ii 9440500990 Rev D

Basler Electric does not assume any responsibility to compliance or noncompliance with national code, local code,
For terms of service relating to this product and software, see the Commercial Terms of Products and Services

document available at www.basler.com/terms.

This publication contains confidential information of Basler Electric Company, an Illinois corporation. It is loaned for

and options are subject to modification without notice. Over time, improvements and revisions may be made to this
manual.

The English-language version of this manual serves as the only approved manual version.

12570 State Route 143

Highland IL 62249-1074 USA

www.basler.com

[e-mail]

Tel: [phone]

Fax: [phone]

© 2015 by Basler Electric

All rights reserved

First printing: October 2012

Warning!

READ THIS MANUAL. Read this manual before installing, operating, or maintaining the DECS-250N.

Note all warnings, cautions, and notes in this manual as well as on the product. Keep this manual with
the product for reference. Only qualified personnel should install, operate, or service this system.
Failure to follow warning and cautionary labels may result in personal injury or property damage.
Exercise caution at all times.

or any other applicable code. This manual serves as reference material that must be well understood prior to
installation, operation, or maintenance.

confidential use, subject to return on request, and with the mutual understanding that it will not be used in any
manner detrimental to the interests of Basler Electric Company and used strictly for the purpose intended.

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

publication. Before performing any of the following procedures, contact Basler Electric for the latest revision of this

Preface DECS-250N

9440500990 Rev D iii

This product contains, in part, open source softw are (software licensed in a way that ensures freedom to run,
copy, distribute, study, change, and improve the software) and you are granted a license to that software under the

formation is provided above). A fee of no more than our cost of physically performing the source code distribution

Portions of this software are copyright © 2014 The Free Type Project (www.freetype.org). All rights reserved.

terms of either the GNU General Public License or GNU Lesser General Public License. The licenses, at the time
of sale of the product, allow you to freely copy, modify, and redistribute that software and no other statement or
documentation from us, including our End User License Agreement, places any additional restrictions on what you
may do with that software.
For at least three (3) years from the date of distribution of this product, a machine-readable copy of the complete
corresponding source code for the version of the programs distributed to you will be sent upon request (contact
in
is charged.
The source code is distributed in the hope that it will be useful, but WITHOUT ANY REPRESENTATION or
WARRANTY or even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Refer to the source code distribution for additional restrictions regarding warranty and copyrights.
For a complete copy of GNU GENERAL PUBLIC LICENSE Version 2, June 1991 or GNU LESSER GENERAL
PUBLIC LICENSE Version 2.1, February 1999 refer to www.gnu.org or contact Basler Electric. You, as a Basler
Electric Company customer, agree to abide by the terms and conditions of GNU GENERAL PUBLIC LICENSE
Version 2, June 1991 or GNU LESSER GENERAL PUBLIC LICENSE Version 2.1, February 1999, and as such
hold Basler Electric Company harmless related to any open source software incorporated in this product. Basler
Electric Company disclaims any and all liability associated with the open source software an d the user agr ees to
defend and indemnify Basler Electric Company, its directors, officers, and employees from and against any and all
losses, claims, attorneys' fees, and expenses arising from the use, sharing, or redistribution of the software.
Review the software website for the latest version of the software documentation.

DECS-250N Preface

iv 9440500990 Rev D

Revision History DECS-250N

9440500990 Rev D v

Contents

Introduction ................................................................................................................................................. 1

Features and Functions ............................................................................................................................. 1

Applications ............................................................................................................................................... 2

Package ..................................................................................................................................................... 2

Optional Features and Capabilities ........................................................................................................... 2

Style Number ......................................................................................................................................... 3

Storage ...................................................................................................................................................... 3

Electrolytic Capacitor Considerations .................................................................................................... 3

Controls and Indicators .............................................................................................................................. 5

Front Panel Illustration and Description .................................................................................................... 5

Menu Navigation ........................................................................................................................................ 6

Adjusting Settings ...................................................................................................................................... 7

Display Setup ............................................................................................................................................ 7

LCD ........................................................................................................................................................ 7

Sleep Mode ............................................................................................................................................ 7

Language ............................................................................................................................................... 7

Screen Scrolling ..................................................................................................................................... 8

Power Inputs ................................................................................................................................................ 9

Control Power ............................................................................................................................................ 9

Operating Power ........................................................................................................................................ 9

Power Stage ............................................................................................................................................... 11

Field Transient Protection........................................................................................................................ 11

Inverting Style Excitation System Compatibility ...................................................................................... 11

Voltage and Current Sensing ................................................................................................................... 13

Generator Voltage ................................................................................................................................... 13

Generator Current ................................................................................................................................... 13

Phase Sensing ..................................................................................................................................... 13

Cross-Current Compensation .............................................................................................................. 14

Bus Voltage ............................................................................................................................................. 15

Synchronizer ............................................................................................................................................. 17

Generator Synchronizat ion ...................................................................................................................... 17

Frequency Correction .......................................................................................................................... 17

Voltage Correction ............................................................................................................................... 17

Angle Compensation ........................................................................................................................... 18

Failure of Synchronization ................................................................................................................... 18

Voltage Matching ..................................................................................................................................... 19

Breaker Hardware Configuration ............................................................................................................. 19

Breaker Failure .................................................................................................................................... 19

Generator Breaker ............................................................................................................................... 19

Generator and Bus Condition Detection.................................................................................................. 20

Generator Condition............................................................................................................................. 21

Generator Stability ............................................................................................................................... 21

Bus Condition ....................................................................................................................................... 21

Bus Stability ......................................................................................................................................... 21

Generator Governor Control .................................................................................................................... 23

Regulation .................................................................................................................................................. 25

Regulation Modes .................................................................................................................................... 25

AVR ...................................................................................................................................................... 25

FCR ...................................................................................................................................................... 25

FVR ...................................................................................................................................................... 25

Var ....................................................................................................................................................... 26

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vi 9440500990 Rev D

Power Factor ........................................................................................................................................ 27

Pre-Position Setpoints ............................................................................................................................. 27

Transient Boost ....................................................................................................................................... 28

Operation with Paralleled Generators ..................................................................................................... 29

Reactive Droop Compensation ............................................................................................................ 29

Cross-Current Compensation .............................................................................................................. 29

Network Load Sharing ......................................................................................................................... 29

Line Drop Compensation ..................................................................................................................... 30

Autotracking ............................................................................................................................................. 31

Internal Setpoint Tracking .................................................................................................................... 31

External Setpoint Tracking ................................................................................................................... 32

Setpoint Configure ................................................................................................................................... 32

Auxiliary Control ....................................................................................................................................... 33

Auxiliary Control Input Type .................................................................................................................... 33

Auxiliary Control Input Function .............................................................................................................. 33

PSS Test Input ..................................................................................................................................... 33

Limiter Scaling ..................................................................................................................................... 33

Setpoint Limits ..................................................................................................................................... 33

Auxiliary Control Gains ............................................................................................................................ 33

AVR Mode ............................................................................................................................................ 34

FCR Mode ............................................................................................................................................ 34

FVR Mode ............................................................................................................................................ 34

Var Mode ............................................................................................................................................. 34

Power Factor Mode.............................................................................................................................. 34

Summing Type ........................................................................................................................................ 34

Contact Inputs and Outputs ..................................................................................................................... 37

Contact Inputs ......................................................................................................................................... 37

Start and Stop Inputs ........................................................................................................................... 37

Programmable Inputs .......................................................................................................................... 37

Contact Outputs ....................................................................................................................................... 38

Watchdog Output ................................................................................................................................. 38

Programmable Outputs ........................................................................................................................ 38

Protection................................................................................................................................................... 41

Voltage Protection ................................................................................................................................... 41

Overexcitation (Volts per Hertz) ........................................................................................................... 41

Generator Undervoltage ...................................................................................................................... 43

Generator Overvoltage ........................................................................................................................ 44

Loss of Sensing ................................................................................................................................... 44

Frequency Protection .............................................................................................................................. 45

Overfrequency ..................................................................................................................................... 45

Underfrequency ................................................................................................................................... 45

Power Protection ..................................................................................................................................... 46

Reverse Power .................................................................................................................................... 46

Loss of Excitation ................................................................................................................................. 46

Field Protection ........................................................................................................................................ 48

Field Overvoltage ................................................................................................................................. 48

Field Overcurrent ................................................................................................................................. 48

Exciter Diode Monitor .......................................................................................................................... 50

Power Input Failure .............................................................................................................................. 52

Sync-Check Protection ............................................................................................................................ 53

Generator Frequency Less Than 10 Hertz .............................................................................................. 54

Configurable Protection ........................................................................................................................... 54

Limiters ...................................................................................................................................................... 57

Overexcitation Limiter .............................................................................................................................. 57

Summing Point OEL ............................................................................................................................ 57

Takeover OEL ...................................................................................................................................... 58

Contents DECS-250N

9440500990 Rev D vii

Underexcitation Limiter ............................................................................................................................ 61

Stator Current Limiter .............................................................................................................................. 63

Low-Level Limiting ............................................................................................................................... 64

High-Level Limiting .............................................................................................................................. 64

Initial Delay .......................................................................................................................................... 64

Var Limiter ............................................................................................................................................... 65

Limiter Scaling ......................................................................................................................................... 65

Underfrequency Limiter ........................................................................................................................... 66

Volts per Hertz ..................................................................................................................................... 67

Metering ..................................................................................................................................................... 69

Metering Explorer .................................................................................................................................... 69

HMI ...................................................................................................................................................... 69

BESTCOMSPlus® ................................................................................................................................ 69

Metered Parameters ................................................................................................................................ 70

Generator ............................................................................................................................................. 70

Power ................................................................................................................................................... 70

Bus ....................................................................................................................................................... 71

Field ..................................................................................................................................................... 72

PSS ...................................................................................................................................................... 72

Synchronization ................................................................................................................................... 73

Auxiliary Control Input .......................................................................................................................... 73

Tracking ............................................................................................................................................... 73

Control Panel ....................................................................................................................................... 74

Metering Summary............................................................................................................................... 75

Status Indication ...................................................................................................................................... 76

System Status ...................................................................................................................................... 76

Inputs ................................................................................................................................................... 77

Outputs ................................................................................................................................................ 78

Network Load Share ............................................................................................................................ 79

Configurable Protection ....................................................................................................................... 79

Alarms .................................................................................................................................................. 80

Real-Time Clock .................................................................................................................................. 83

Auto Export Metering ............................................................................................................................... 84

Event Recorder .......................................................................................................................................... 85

Sequence-of-Events Recording .............................................................................................................. 85

Data Logging ........................................................................................................................................... 85

Setup .................................................................................................................................................... 86

Triggers ................................................................................................................................................ 86

Trending .................................................................................................................................................. 89

Power System Stabilizer ........................................................................................................................... 91

Supervisory Function and Setting Groups............................................................................................... 91

Supervisory Function ........................................................................................................................... 91

Setting Groups ..................................................................................................................................... 91

Theory of Operation ................................................................................................................................. 91

Speed Signal ........................................................................................................................................ 93

Rotor Frequency Calculation ............................................................................................................... 93

Generator Electrical Power Sig na l ....................................................................................................... 93

Derived Mechanical Power Signa l ....................................................................................................... 94

Stabilizing Signal Selection .................................................................................................................. 94

Torsional Filters ................................................................................................................................... 95

Phase Compensation .......................................................................................................................... 95

Washout Filter and Logic Limiter ......................................................................................................... 95

Output Stage ........................................................................................................................................ 96

Terminal Voltage Limiter ...................................................................................................................... 96

Stability Tuning ....................................................................................................................................... 101

AVR Mode ............................................................................................................................................. 101

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viii 9440500990 Rev D

Predefined Stability Settin g s .............................................................................................................. 101

Custom Stability Settings ................................................................................................................... 101

Auto Tuning ........................................................................................................................................ 103

FCR and FVR Modes ............................................................................................................................ 104

FCR Mode Stability Settings .............................................................................................................. 104

FVR Mode Stability Settings .............................................................................................................. 105

Other Modes and Functions .................................................................................................................. 106

Var Mode ........................................................................................................................................... 106

Power Factor Mode............................................................................................................................ 106

Overexcitation Limiter (OEL) ............................................................................................................. 106

Underexcitation Limiter (UEL) ............................................................................................................ 106

Stator Current Limiter (SCL) .............................................................................................................. 106

Var Limiter .......................................................................................................................................... 106

Voltage Matching ............................................................................................................................... 106

Mounting .................................................................................................................................................. 109

Mounting Considerations ....................................................................................................................... 109

Projection Mounting ............................................................................................................................... 109

Behind-the-Panel Mounting ................................................................................................................... 109

Terminals and Connectors ..................................................................................................................... 115

Overview ................................................................................................................................................ 115

Terminal Types ...................................................................................................................................... 119

Typical Connections ............................................................................................................................... 121

BESTCOMSPlus® Software ..................................................................................................................... 125

General Description ............................................................................................................................... 125

Installation ............................................................................................................................................. 126

Install BESTCOMSPlus® .................................................................................................................... 126

Activation of the DECS-250N Plugin for BESTCOMSPlus® .................................................................. 126

Connect a USB Cable ........................................................................................................................ 127

Start BESTCOMSPlus® and Activate DECS-250N Plugin Automatically .......................................... 127

Manual Activation of the DECS-250N Plug in .................................................................................... 129

Establishing Communicat io n ............................................................................................................. 130

Menu Bars ............................................................................................................................................. 130

Upper Menu Bar (BESTCOMSPlus® Shell) ....................................................................................... 130

Lower Menu Bar (DECS-250N Plugin) .............................................................................................. 132

Settings Explorer ................................................................................................................................... 132

Metering Explorer .................................................................................................................................. 132

Settings File Management ..................................................................................................................... 133

Opening a Settings File ..................................................................................................................... 133

Saving a Settings File ........................................................................................................................ 133

Upload Settings and/or Logic to Device ............................................................................................ 133

Download Settings and Logic from Device ........................................................................................ 133

Printing a Settings File ....................................................................................................................... 133

Comparing Settings Files ................................................................................................................... 133

Automatic Metering Export .................................................................................................................... 135

Firmware Updates ................................................................................................................................. 135

Upgrading Firmware in Expansion Modules ...................................................................................... 136

Upgrading Firmware in the DECS-250N............................................................................................ 137

BESTCOMSPlus® Updates .................................................................................................................... 138

BESTlogic™Plus ...................................................................................................................................... 139

Introduction ............................................................................................................................................ 139

Overview of BESTlogic™Plus ............................................................................................................... 139

BESTlogic™Plus Composition .......................................................................................................... 140

Logic Schemes ...................................................................................................................................... 154

The Active Logic Scheme .................................................................................................................. 154

Sending and Retrieving Logic Schemes ............................................................................................ 154

Default Logic Schemes ...................................................................................................................... 155

Contents DECS-250N

9440500990 Rev D ix

Programming BESTlogic ™Plus.............................................................................................................. 158

Pickup and Dropout Timers ............................................................................................................... 159

Offline Logic Simulator .......................................................................................................................... 160

BESTlogic™Plus File Management ...................................................................................................... 160

Saving a BESTlogicPlus File ............................................................................................................. 161

Opening a BESTlogicPlus File ........................................................................................................... 161

Protecting a BESTlogicPlus File ........................................................................................................ 161

Uploading a BESTlogicPlus File ........................................................................................................ 161

Downloading a BESTlogicPlus File ................................................................................................... 161

Copying and Renaming Preprogrammed Logic Sche mes ................................................................ 161

Printing a BESTlogicPlus File ............................................................................................................ 162

Clearing the On-Screen Logic Diagram ............................................................................................. 162

BESTlogic™Plus Examples .................................................................................................................. 162

Example 1 - GOVR Logic Block Connections ................................................................................... 162

Example 2 - AND Gate Connections ................................................................................................. 162

Communication ....................................................................................................................................... 163

Local Communication ............................................................................................................................ 163

Communication with a Second DECS ................................................................................................... 163

Modbus™ Communication ..................................................................................................................... 164

RS-485 Port ....................................................................................................................................... 164

Ethernet Port ...................................................................................................................................... 165

CAN Communication ............................................................................................................................. 166

Connections ....................................................................................................................................... 166

Port Configuration .............................................................................................................................. 166

Remote Module Setup ....................................................................................................................... 166

Ethernet Communication ....................................................................................................................... 167

Ethernet Connection .......................................................................................................................... 167

PROFIBUS Communication .................................................................................................................. 170

Configuration ........................................................................................................................................... 171

Generator, Field, and Bus Ratings ........................................................................................................ 171

Sensing Transformer Ratings and Configuration .................................................................................. 172

Generator PT ..................................................................................................................................... 172

Generator CTs ................................................................................................................................... 172

Bus PT ............................................................................................................................................... 172

Bridge Operating Power Configuration .................................................................................................. 173

Operating Power Input ....................................................................................................................... 173

Modes of Operation ........................................................................................................................... 173

Rated Frequency ............................................................................................................................... 174

Maximum Over-Speed ....................................................................................................................... 174

Startup Functions .................................................................................................................................. 174

Soft Start ............................................................................................................................................ 174

Field Flashing ..................................................................................................................................... 174

Device Information ................................................................................................................................. 175

Firmware and Product Information .................................................................................................... 175

Device Identification ........................................................................................................................... 175

Display Units .......................................................................................................................................... 176

Security .................................................................................................................................................... 179

Password Access .................................................................................................................................. 179

Password Creation and Configuration ............................................................................................... 179

Port Security .......................................................................................................................................... 180

Port Access Configuration ................................................................................................................. 181

Login and Access Controls .................................................................................................................... 181

Access Timeout ................................................................................................................................. 181

Login Failure ...................................................................................................................................... 182

Timekeeping ............................................................................................................................................ 183

Time and Date Format........................................................................................................................... 183

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x 9440500990 Rev D

Daylight Saving Time Adjustments ........................................................................................................ 183

Network Time Protocol (NTP) ............................................................................................................... 183

NTP Settings ...................................................................................................................................... 183

IRIG ....................................................................................................................................................... 183

Testing ...................................................................................................................................................... 187

Real-Time Metering Analysis ................................................................................................................ 187

Graph Parameters ............................................................................................................................. 188

Frequency Response ............................................................................................................................ 188

Test Mode .......................................................................................................................................... 188

Bode Plotting ...................................................................................................................................... 189

Transfer Function ............................................................................................................................... 189

Frequency Response ......................................................................................................................... 190

Time Response ..................................................................................................................................... 190

Signal Input ........................................................................................................................................ 191

Test Signal Characteristics ................................................................................................................ 191

Step Response Analys is ........................................................................................................................ 192

AVR, FCR, and FVR Tabs ................................................................................................................. 192

Var and PF Tabs ................................................................................................................................ 193

Analysis Options .................................................................................................................................... 193

Layout Tab ......................................................................................................................................... 193

Graph Display Tab ............................................................................................................................. 194

CAN Communication .............................................................................................................................. 195

Introduction ............................................................................................................................................ 195

CAN Parameters ................................................................................................................................... 195

Diagnostic Trouble Codes (DTCs) ..................................................................................................... 197

Modbus™ Communication ...................................................................................................................... 199

Introduction ............................................................................................................................................ 199

Message Structure ............................................................................................................................. 199

Modbus Modes of Operation ................................................................................................................. 200

Modbus™ Over Serial Line ................................................................................................................. 200

Modbus on TCP/IP............................................................................................................................. 201

Error Handling and Exception Responses ......................................................................................... 202

DECS-250N Modbus™ via Ethernet .................................................................................................. 203

Detailed Message Query and Response for RTU Transmission Mode ................................................ 203

Read Holding Registers ..................................................................................................................... 203

Return Query Data ............................................................................................................................. 203

Restart Communications Option ........................................................................................................ 204

Listen Only Mode ............................................................................................................................... 204

Preset Multiple Registers ................................................................................................................... 204

Preset Single Register ....................................................................................................................... 205

Data Formats ......................................................................................................................................... 206

Floating Point Data Format (Float) .................................................................................................... 206

Long Integer Data Format (Uint32) .................................................................................................... 207

Integer Data Format (Uint16) or Bit-Mapped Variables in Uint16 Format ......................................... 207

Short Integer Data Format/Byte Character Data Format (Uint8) ....................................................... 207

String Data Format (String) ................................................................................................................ 207

CRC Error Check ............................................................................................................................... 208

Secure DECS-250N Login via Modbus ................................................................................................. 208

Modbus Parameters .............................................................................................................................. 208

General .............................................................................................................................................. 208

Security .............................................................................................................................................. 209

Binary Points ...................................................................................................................................... 209

Metering ............................................................................................................................................. 218

Limiters .............................................................................................................................................. 223

Setpoints ............................................................................................................................................ 225

Global Settings ................................................................................................................................... 227

Relay Settings .................................................................................................................................... 228

Contents DECS-250N

9440500990 Rev D xi

Protection Settings ............................................................................................................................. 230

Gains Settings .................................................................................................................................... 232

Legacy Modbus .................................................................................................................................. 233

PROFIBUS Communication ................................................................................................................... 243

Data Types ............................................................................................................................................ 243

Float/UINT32 ...................................................................................................................................... 243

UINT8 ................................................................................................................................................. 243

Setup ..................................................................................................................................................... 245

PROFIBUS Param eter s......................................................................................................................... 246

Maintenance ............................................................................................................................................ 303

Storage .................................................................................................................................................. 303

Preventive Maintenance ........................................................................................................................ 303

Connections ....................................................................................................................................... 303

Electrolytic Capacitors ....................................................................................................................... 303

Cleaning the Front Panel ....................................................................................................................... 303

Troubleshooting ..................................................................................................................................... 304

DECS-250N Appears Inoperative ...................................................................................................... 304

Display Blank or Frozen ..................................................................................................................... 304

Generator Voltage Does Not Build .................................................................................................... 304

Low Generator Voltage in AVR Mode ................................................................................................ 304

High Generator Voltage in AVR Mode ............................................................................................... 304

Generator Voltage Unstable (Hunting) .............................................................................................. 305

Protection or Limit Annunciation ........................................................................................................ 305

HMI Meter Readings Incorrect ........................................................................................................... 305

No Communication ............................................................................................................................ 305

DECS-250N Reboots Frequently ....................................................................................................... 305

Support .................................................................................................................................................. 305

Specifications .......................................................................................................................................... 307

Operating Power .................................................................................................................................... 307

Voltage Range ................................................................................................................................... 307

Frequency Range (Style Dependent) ................................................................................................ 307

Control Power ........................................................................................................................................ 307

Style LXXXXXX .................................................................................................................................. 307

Style CXXXXXX ................................................................................................................................. 307

Terminals ........................................................................................................................................... 308

Generator and Bus Voltage Sensing ..................................................................................................... 308

Terminals ........................................................................................................................................... 308

50 Hz Sensing Voltage Nominal Input, Range .................................................................................. 308

60 Hz Sensing Voltage Nominal Input, Range .................................................................................. 308

Generator Current Sensing ................................................................................................................... 308

Burden ............................................................................................................................................... 308

Terminals ........................................................................................................................................... 308

Accessory Inputs ................................................................................................................................... 309

Current Input ...................................................................................................................................... 309

Voltage Input ...................................................................................................................................... 309

Contact Inputs ....................................................................................................................................... 309

Terminals ........................................................................................................................................... 309

Communication Ports ............................................................................................................................ 309

Universal Serial Bus (USB) ................................................................................................................ 309

RS-232 ............................................................................................................................................... 309

RS-485 ............................................................................................................................................... 310

Ethernet ............................................................................................................................................. 310

Controller Area Network (CAN) ......................................................................................................... 310

IRIG Time Synchronization Input .......................................................................................................... 310

Contact Outputs ..................................................................................................................................... 310

Field Power Output ................................................................................................................................ 311

Maximum Positive Forcing Voltag e ................................................................................................... 311

DECS-250N Contents

xii 9440500990 Rev D

Maximum Negative Forcing Voltage .................................................................................................. 311

Minimum Field Resistance ................................................................................................................. 311

Regulation ............................................................................................................................................. 311

FCR Operating Mode ......................................................................................................................... 311

FVR Operating Mode ......................................................................................................................... 311

AVR Operating Mode ......................................................................................................................... 311

Var Operating Mode........................................................................................................................... 312

Power Factor Operating Mode ........................................................................................................... 312

Parallel Compensation .......................................................................................................................... 312

Setpoint Range .................................................................................................................................. 312

Generator Protection Functions ............................................................................................................ 312

Overvoltage (59) and Undervoltage (27) ........................................................................................... 312

Loss of Sensing ................................................................................................................................. 312

Overfrequency (81O) and Underfrequency (81U) ............................................................................. 313

Reverse Power (32R) ........................................................................................................................ 313

Loss of Excitation (40Q) .................................................................................................................... 313

Field Protection Functions ..................................................................................................................... 313

Field Overvoltage ............................................................................................................................... 313

Field Overcurrent ............................................................................................................................... 313

Loss of PMG ...................................................................................................................................... 314

Exciter Diode Monitor (EDM) ............................................................................................................. 314

Synchronism Check (25) Protection ...................................................................................................... 314

Voltage Difference ............................................................................................................................. 314

Slip Angle ........................................................................................................................................... 314

Slip Frequency ................................................................................................................................... 314

Startup ................................................................................................................................................... 314

Soft Start Level .................................................................................................................................. 314

Soft Start Time ................................................................................................................................... 314

Field Flash Dropout Level .................................................................................................................. 314

Maximum Field Flash Time ................................................................................................................ 315

Voltage Matching ................................................................................................................................... 315

On-Line Overexcitation Limiting ............................................................................................................ 315

High Current Level ............................................................................................................................. 315

Medium Current Level ....................................................................................................................... 315

Low Current Level .............................................................................................................................. 315

Off-Line Overexcitation Limiting ............................................................................................................ 315

High Current Level ............................................................................................................................. 315

Low Current Level .............................................................................................................................. 315

Sequence of Events Recording (SER)2 ................................................................................................ 315

Data Logging (Oscillography) ................................................................................................................ 316

Environment .......................................................................................................................................... 316

Temperature ...................................................................................................................................... 316

Humidity ............................................................................................................................................. 316

Salt Fog .............................................................................................................................................. 316

Type Tests ............................................................................................................................................. 316

Shock ................................................................................................................................................. 316

Vibration ............................................................................................................................................. 316

Impulse .............................................................................................................................................. 316

Transients .......................................................................................................................................... 316

Static Discharge ................................................................................................................................. 316

Radio Interference ............................................................................................................................. 316

HALT (Highly Accelerated Life Testing) ............................................................................................ 316

Patent .................................................................................................................................................... 317

Physical ................................................................................................................................................. 317

Regulatory Standards ............................................................................................................................ 317

Maritime Recognition ......................................................................................................................... 317

UL Approval ....................................................................................................................................... 317

CSA Certification ................................................................................................................................ 317

Contents DECS-250N

9440500990 Rev D xiii

CE Compliance .................................................................................................................................. 317

EAC Mark (Eurasian Conformity) ...................................................................................................... 318

Analog Expansion Module ..................................................................................................................... 319

General Information ............................................................................................................................... 319

Features ................................................................................................................................................ 319

Specifications ........................................................................................................................................ 319

Operating Power ................................................................................................................................ 319

Analog Inputs ..................................................................................................................................... 319

RTD Inputs ......................................................................................................................................... 319

Thermocouple Inputs ......................................................................................................................... 319

Analog Outputs .................................................................................................................................. 319

Communication Interface ................................................................................................................... 320

Type Tests ......................................................................................................................................... 320

Environment ....................................................................................................................................... 320

UL Approval ....................................................................................................................................... 320

CSA Certification ................................................................................................................................ 320

CE Compliance .................................................................................................................................. 321

Physical .............................................................................................................................................. 321

Installation ............................................................................................................................................. 321

Mounting ............................................................................................................................................ 321

Connections ....................................................................................................................................... 322

Communications .................................................................................................................................... 328

Functional Description ........................................................................................................................... 328

Analog Inputs ..................................................................................................................................... 328

RTD Inputs ......................................................................................................................................... 329

Thermocouple Inputs ......................................................................................................................... 330

Analog Outputs .................................................................................................................................. 331

Metering ................................................................................................................................................. 332

Analog Inputs ..................................................................................................................................... 332

RTD Inputs ......................................................................................................................................... 333

Thermocouple Inputs ......................................................................................................................... 333

Analog Input Values ........................................................................................................................... 333

Analog Outputs .................................................................................................................................. 335

Maintenance .......................................................................................................................................... 335

Firmware Updates.............................................................................................................................. 335

Contact Expansion Module .................................................................................................................... 337

General Information ............................................................................................................................... 337

Features ................................................................................................................................................ 337

Specifications ........................................................................................................................................ 337

Operating Power ................................................................................................................................ 337

Contact Inputs .................................................................................................................................... 337

Contact Outputs ................................................................................................................................. 337

Communication Interface ................................................................................................................... 337

Type Tests ......................................................................................................................................... 337

Environment ....................................................................................................................................... 338

UL Approval (CEM-2020 and CEM-2020H) ...................................................................................... 338

CSA Certification ................................................................................................................................ 338

CE Compliance .................................................................................................................................. 338

Physical .............................................................................................................................................. 339

Installation ............................................................................................................................................. 339

Mounting ............................................................................................................................................ 339

Connections ....................................................................................................................................... 341

Communications .................................................................................................................................... 346

Functional Description ........................................................................................................................... 346

Contact Inputs .................................................................................................................................... 346

Contact Outputs ................................................................................................................................. 347

Metering ................................................................................................................................................. 348

DECS-250N Contents

xiv 9440500990 Rev D

Contact Inputs .................................................................................................................................... 348

Contact Outputs ................................................................................................................................. 348

Maintenance .......................................................................................................................................... 348

Firmware Updates.............................................................................................................................. 348

Revision History ...................................................................................................................................... 349

Contents DECS-250N

9440500990 Rev C 1

Introduction

DECS-250N Digital Excitation Control Systems offer precise excitation control and machine protection in
a compact package. DECS-250N adaptability to many applications is assured through configurable
contact inputs and outputs, flexible communication capabilities, and programmable logic implemented
with the provided BESTCOMSPlus

Features and Functions

DECS-250N features and functions include:

• Precise excitation control for synchronous generator or synchronous motor applications
o Power factor and var metering values will be opposite in motor mode

• Five excitation control modes:

o Automatic Voltage Regulation (AVR)
o Field Current Regulation (FCR)
o Field Voltage Regulation (FVR)
o Power Factor Regulation (PF)
o Var Regulation (var)

• Three pre-position setpoints for each excitation control mode

• Internal tracking between operating mode setpoints and external tracking of a second DECS

excitation setpoint

• Two PID stability groups with Auto Tune feature

• Remote setpoint control input accepts analog voltage or current control signal

• Real-time metering

• Optional automatic synchronizer

• Optional integrated power system stabilizer (PSS)

o Generator or motor control modes, accommodates phase rotation changes between

modes

o Speed and power sensing or speed-only sensing
o Two wattmeter or three-wattmeter methods of power measurement

• Soft start and voltage buildup control

• Five limiting functions:

o Overexcitation: summing point and takeover
o Underexcitation
o Stator current
o Reactive power (var)
o Underfrequency

• Twenty protection functions:

o Generator undervoltage (27)
o Generator overvoltage (59)
o Loss of sensing (LOS)
o Overfrequency (81O)
o Underfrequency (81U)
o Reverse power (32R)
o Loss of excitation (40Q)
o Field overvoltage
o Field overcurrent
o Loss of PMG
o Exciter diode failure
o Sync-check (25)
o Eight configurable protection elements

• IRIG or network time synchronization

• Sixteen contact sensing inputs

o Two fixed-funct ion inputs : Start and Sto p
o Fourteen programmab le in puts

®

software.

DECS-250N Introduction

2 9440500990 Rev C

• Twelve contact outputs

o One, fixed-function output: Watchdog (SPDT configuration)
o Eleven programmable outputs

• Flexible communication

o Serial communication through front-panel USB port
o Modbus communication through RS-485 port or Modbus TCP
o Ethernet communication through an optional copper or fiber optic port
o CAN communication with an ECU (engine control unit), optional AEM-2020 Analog

Expansion Module, or optional CEM-2020 Contact Expansion Module

o Optional PROFIBUS communication protocol

• Data logging, sequence of events recording, and trending

• Optional CEM-2020 Contact Expansion Module provides:

o Ten contact inputs
o Eighteen contact outputs (CEM-2020H) or 24 contact outputs (CEM-2020)
o Customizable input and output functions assigned through BESTlogic™Plus

programmable logic

o Communication via CAN protocol

• Optional AEM-2020 Analog Expansion Module provides:

o Eight analog inputs
o Eight resistive thermocouple device (RTD) inputs
o Two thermocouple inputs
o Four analog outputs
o Customizable input and output functions assigned through BESTlogicPlus programmable

logic

o Communication via CAN protocol

Applications

The DECS-250N is intended for synchronous generator or synchronous motor applications. The DECS­250N controls the machine output through the application of regulated DC excitation power to the exciter
field. The level of excitation power is based on the monitored voltage and current, and a regulation
setpoint established by the user. The operating mode, generator or motor, is changed on the Operating
Mode settings screen. Power factor and var metering values will be opposite in motor mode.

Excitation power is supplied from the DECS-250N by means of a six-SCR, full-wave bridge. It is capable
of two-quadrant operation; it can produce negative as well as positive output power. With nominal
operating voltage applied, t he DECS-250N is capable of supplying 20 Adc continuously at a nominal
voltage of 32, 63, or 125 Vdc.

Package

A single, compact package contains all excitation control and power components.
A front panel HMI provides local annunciation and control through a backlit liquid crystal display (LCD),

light-emitting diodes (LEDs), and pushbuttons. Remote annunciation and control is provided through a
flexible communication interface which accommodates Ethernet, Modbus, optional PROFIBUS, and the
optional Interactive Display Panel (IDP-800).

Optional Features and Capabilities

DECS-250N optional features and capabilities are defined by a combination of letters and numbers that
make up the style number. The model number and style number describe options and characteristics in a
specific device and appear on a label affixed to the device.

Introduction DECS-250N

9440500990 Rev C 3

Style Number

The style number identification chart in Figure 1 defines the electrical characteristics and operational
features available in the DECS-250N.

Figure 1. DECS-250N Style Chart

Storage

If a DECS-250N will not be placed in service right away, store it in the original shipping carton in a
moisture- and dust-free environment. The temperature of the storage environment must be within the
range of –40 to 85°C (–40 to 185°F).

Electrolytic Capacitor Considerations

The DECS-250N contains long-life aluminum electrolytic capacitors. For a DECS-250N kept in storage as
a spare, the life of these capacitors can be maximized by energizing the device for 30 minutes once per
year. Refer to the energizing procedures provided in Maintenance.

DECS-250N Introduction

4 9440500990 Rev C

Introduction DECS-250N

9440500990 Rev D 5

Controls and Indicators

All controls and indicators are located on the front panel and consist of pushbuttons, LED indicators, and
a liquid-crystal display (LCD).

Front Panel Illustration and Description

DECS-250N controls and indicators are illustrated in Figure 2 and described in Table 1. The locators and
descriptions of Table 1 correspond to the locators shown in Figure 2.

Figure 2. Front Panel Controls and Indicators

DECS-250N Controls and Indicators

6 9440500990 Rev D

Locator

Description

A

Display. The liquid crystal display (LCD) serves as a local source of information

64 dot pixel, backlit LCD displays white characters on a blue background.

B

Pre-Position Indicator. This red light emitting diode (LED) lights when the active mode
setpoint is at any of the three pre-position (predefined) settings.

C

Limit Indicators. Two red LEDs indicate when the active mode setpoint reaches the
minimum or maximum value.

D

Scrolling Pushbuttons. These four buttons are used to scroll up, down, left, and right

scrolling pushbuttons change the value of the variable.

E

Reset Pushbutton. This button cancels editing sessions, resets alarm annunciations
and latched alarm relays, and can be used for quick access to the metering screen.

F

Communication Port. This type B USB jack connects the DECS-250N with a PC

Caution

G

Edit Pushbutton. Pressing this button starts an editing session and enables changes to
pressed to save the settings changes.

H

Null Balance Indicator. This green LED lights when the setpoint of the inactive
mode.

I

PSS Active Indicator. This red LED lights when the integrated power system stabilizer
disturbance.

J

Internal Tracking Indicator. This red LED lights when any inactive mode (AVR, FCR,
“bumpless” transfer when changing active modes.

Table 1. Front Panel Control and Indicators Descriptions

provided by the DECS-250N. The LCD displays operating setpoints, loop gains,
metering, protection functions, system parameters, and general settings. The 128 by

through the menus displayed on the LCD (locator A). During an editing session, the left
and right scrolling pushbuttons select the variable to be changed and the up and down

operating BESTCOMSPlus® for local communication. BESTCOMSPlus is supplied
with the DECS-250N.

In accordance with the guidelines defined in USB standards, the USB
port on this device is not isolated. To prevent damage to a connected
PC or laptop, the DECS-250N must be properly tied to ground.

DECS-250N settings. At the conclusion of the editing session, the Edit pushbutton is

operating modes (AVR, FCR, FVR, var, and PF) match the setpoint of the active

is enabled and can generate a stabilizing signal in response to a power system

FVR, Var, or Power Factor) is tracking the setpoint of the active mode to achieve a

Menu Navigation

The DECS-250N provides local access to DECS-250N settings and metering values through a menu
structure displayed on the front panel LCD. An overview of the menu structure is illustrated in Figure 3.
Movement through the menu structure is achieved by pressing the four scrolling pu s hbuttons.

Controls and Indicators DECS-250N

9440500990 Rev D 7

Figure 3. Menu Structure Overview

Adjusting Settings

A setting adjustment is made at the front panel by performing the following steps.

1. Navigate to the screen listing the setting to be changed.

2. Press the Edit button and enter the appropriate username and password to gain the needed level

of security access. (Information about implementing and using username and password
protection is provided in the Security chapter of this manual.)

3. Highlight the desired setting and press the Edit button to view the setting editing screen. This

screen lists the setting range or the permissible setting selection.

4. Use the scrolling pushbuttons to select the setting digits/selections and adjust/change the setting.

5. Press the Edit button to save the change.

Display Setup

BESTCOMSPlus Navigation Path: Settings Explorer, General Settings, Front Panel HMI
HMI Navigation Path: Settings, General Settings, Front Panel HMI

Front panel display appearance and behavior can be customized to meet user preferences and site
conditions. These BESTCOMSPlus settin gs are illustr a ted in Figure 4.

LCD

LCD setup includes a contrast adjustmentA to suit the viewing angle used or compensate for
environmental conditions. The ability to reverse the display colors
conditions and user preferences.

B

is provided to accommodate lighting

Sleep Mode

Sleep modeC reduces the demand on control power by turning off the LCD backlight when no pushbutton
activity is seen for the duration of the LCD Backlight Timeout setting

D

.

Language

Language modules are available for the DECS-250N. Once a language module is implemented it can be
enabled via the Language Selection sett ing

E

.

DECS-250N Controls and Indicators

8 9440500990 Rev D

Screen Scrolling

The display can be set to automatically scroll through a user-selected listF of metered values. This feature
is enabled and disabled with the Enable Scroll setting
with the Scroll Time Delay setting

H

.

G

. The rate at which scrolling occurs is configured

Figure 4. Front Panel HMI Settings

A

Contrast Value (%): Adjustable from 0 to 100 in 1% increments.

B

Invert display: Deselect for white characters on a blue background. Select for blue characters on a white

background.

C

Sleep Mode: Enable or disable.

D

LCD Backlight Timeout: Adjustable from 0 to 120 seconds in 1 second increments.

E

Language Selection: Select English, Russian, Spanish, German, or Chinese.

F

Scrollable Metering Settings: Select from main categories of GV Primary, GC Primary, CC Primary,
Frequency, Power Primary, PF Primary, Energy Primary, BV Primary, Field Primary, PSS Primary,
Synchronization Primary, Aux Input, Tracking, Real Time Clock, Contact Inputs, Contact Outputs, or
Device ID. Follow this selection by the desired parameters within each category.

G

Enable Scroll: Enable or disable.

H

Scroll Time Delay (s): Adjustable from 1 to 600 seconds in 1 second increments.

Controls and Indicators DECS-250N

9440500990 Rev D 9

Desired Nominal

Excitation Power Voltage

Applied Operating

Power Voltage Range

63 Vdc

100 to 139 Vac

125 Vdc

190 to 277 Vac

250 Vdc

380 to 528 Vac, 50/60 Hz (style xx3xxxx)

DECS-250N

Style Number

Operating Power

Frequency Range

xx1xxxx

50/60 Hz

xx2xxxx

61 to 420 Hz

xx3xxxx

50/60 Hz (480 Vac input, 250 Vdc output)

Power Inputs

Power is applied to two separate inputs: control power and operating power. The control power input
supplies power to an internal power supply that provides power for logic, protection, and control functions.
The power stage uses the operating power input as the source for the converted excitation power that it
applies to the field.

Control Power

Two inputs supply the DECS-250N with control power. One input accepts dc control power and the other
input accepts ac control power. The level of acceptable control power voltage is determined by the style
number. One of two levels is possible. Style Lxxxxxx indicates a nominal voltage of 24 or 48 Vdc and
accepts a voltage range of 16 to 60 Vdc. Style Cxxxxxx indicates a nominal voltage of 120 Vac/125 Vdc
and accepts a voltage range of 90 to 150 Vdc and 82 to 132 Vac (50/60 Hz). One input (either dc or ac) is
sufficient for operation but two inputs provide redundancy (for style Cxxxxxx only). When both control
power inputs are used, an isolation trans former is required for the ac input. DC control power is applied at
terminals BATT+ and BATT–. AC control power is applied at terminals L and N.

Operating Power

Operating power is applied at terminals A, B, and C. To achieve the desired level of excitation, the
appropriate operating power input voltage must be applied. Table 2 lists the acceptable operating power
voltage ranges for the DECS-250N. The operating power frequency range for the DECS-250N is listed in
Table 3.

Table 2. DECS-250N Operating Power Specifications

Table 3. DECS-250N Operating Power Frequency Specifications

DECS-250N Power Inputs

10 9440500990 Rev D

Power Inputs DECS-250N

9440500990 Rev D 11

Power Stage

The DECS-250N supplies regulated dc excitation power to the field of a brushless exciter. Excitation
power is supplied at terminals F+ and F–.

DECS-250N power stage operating power accepts single- or thr ee-phase ac power from a transformer or
PMG. Power stage operating power is applied at terminals A, B, and C. The GND terminal serves as a
ground connection.

The DECS-250N power stage employs a six-SCR, full-wave bridge that converts the ac operating power
input into dc excitation power. It is capable of two-quadrant operation; it can produce negative as well as
positive output power as long as positive current is flowing in the machine field (in excess of the minimum
holding current required for the SCRs). The DECS-250N power stage is capable of supplying 20 Adc
continuously at nominal voltages of 63, 125, or 250 Vdc.

Nominal DECS-250N operating power levels include 480 Vac for a 250 Vdc continuous exciter field
requirement (style XX3XXXX), 240 Vac for a 125 Vdc requirement, or 120 Vac for a 63 Vdc requirement.
The frequency range of the operating power voltage is determined by the DECS-250N style number. Style
XX1XXXX indicates an operating power frequency of 50 to 60 hertz, style XX2XXXX indicates a
frequency of 61 to 420 hertz, and style XX3XXXX limits the frequency to 50 or 60 hertz (for an operating
voltage of 480 Vac).

Field Transient Protec t ion

Fault conditions such as generator overloading or loss of synchronism can induce transients into the field
circuit. If this energy is not dissipated, it has the poten t ial to dam age the pow er stage SCRs. The
DECS-250N has two modes of field transient protection.

Most voltage transients are less than 150 microseconds in duration and are limited to a safe level by
internal DECS-250N components.

During major system faults, an SCR crowbar circuit protects the DECS-250N power stage. When field
overvoltage is detected, the power stage SCR firing pulses are blocked, the crowbar circuit is energized,
and a crowbar annunciation is made. During a normal shutdown, the same actions are taken but no
crowbar annunciation is made.

Inverting Style Excitation System Compatibility

The DECS-250N power stage can be configured for operation in the negative direction to supply the
control windings of an inverting style excitation system.

DECS-250N Power Stage

12 9440500990 Rev D

Power Stage DECS-250N

9440500990 Rev D 13

Note

Voltage and Current Sensing

The DECS-250N senses generator voltage, generator current, and bus voltage through dedicated,
isolated inputs.

Generator Voltage

Three-phase generator sensing voltage is applied to DECS-250N terminals E1, E2, and E3. This sensing
voltage is typically applied through a user-supplied voltage transformer, but may be applied directly.
These terminals accept three-phase, three-wire connections at terminals E1 (A), E2 (B), and E3 (C) or
single-phase connections at E1 (A) and E3 (C).

The generator voltage sensing input accepts a maximum voltage of 600 Vac and has a burden of less
than 1 VA.

The transformer primary and secondary winding voltages are entered in settings that the DECS-250N
uses to interpret the applied sensing voltage and calculate system parameters. The phase rotation of the
generator sensing voltage can be configured as ABC or ACB. Information about configuring the
DECS-250N for the generator sensing voltage is provided in the Configuration chapter of this manual.

Typical generator voltage sensing connections are illustrated in Figure 5.

Figure 5. Typical Generator Voltage Sensing Connections

Generator Current

Generator current sensing inputs consist of three phase-sensing inputs and a sensing input for cross­current compensation.

Current transformer (CT) grounding should be applied in accordance
with local codes and conventions.

Phase Sensing

Three-phase generator sensing current is applied to DECS-250N terminals CTA+ and CTA–, CTB+ and
CTB–, and CTC+ and CTC– through user-supplied current transformers (CTs). Single-phas e gen erat or
sensing current is applied to DECS-250N terminals CTB+ and CTB–. The DECS-250N is compatible with
CTs having 5 Aac or 1 Aac nominal secondary ratings. The DECS-250N uses this secondary rating, along
with the CT nominal primary ratings to interpret the sensed current and calculate system parameters.

DECS-250N Voltage and Current Sensing

14 9440500990 Rev D

Information about configuring the DECS-250N the generator sensing voltage is provided in the
Configuration chapter of this manual. Typical generator phase-current sensing connections are shown in
Figure 6.

Figure 6. Typical Generator Current Sensing Connections

Cross-Current Compensation

Cross-current compensation (reactive differential) mode allows two or more paralleled generators to
share a common load. As shown in Figure 7, each generator is controlled by a DECS-250N using the
DECS-250N cross-current compensation input (terminals CCCT+ and CCCT–) and a dedicated, external
current transformer (CT) to sense generator current. The resistors shown in Figure 7 are used to set the
burden and may be adjusted to suit the application. Ensure that the power rating of the resistors is
adequate for the application.

Figure 7. Connections for Cross-Current Compensation

Voltage and Current Sensing DECS-250N