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DECS-400 Digital Excitation Control System

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EXAMPLE CONNECTIONS

Figure 2 - Typical AC Connection Example

BESTCOMS SOFTWARE

Protection

Underexcitation Limiter

The DECS-400 is supplied with BESTCOMS PC-based software to facilitate system setup and testing. As shown
in the Protection screen, below left, choices are made using drop-down screens, and parameters are familiar.
Reminders are also provided at the bottom of the screen for input units and available parameter range. Tabs
identify general functions, and related functions are on adjacent pages. As shown on the Underexcitation Limiter
Screen, below right, graphics are also used to help visualize input parameters.

Summary of Contents for DECS-400

Page 1: ...itation control flexible logic control and optional power system stabilization for synchronous machines in an integrated package The controller provides an analog output to control the DC output of an external rectifier bridge and monitors machine parameters to control limit and protect the synchronous machine from operating beyond its capability limitations The optional Power System Stabilizer is...

Page 2: ...is suitable for use in single or dual controller systems on virtually any synchronous machine The DECS 400 is at the heart of custom Basler Electric excitation systems that typically include the digital controller supplementary protective and control devices a power potential transformer and associated AC breaker or contactor SCR firing circuits and a power rectifier section as sembled in suitable...

Page 3: ...e Reactive Differential Compensation Enable 2nd Pre Position Accessory Input Remote Set Point Control Analog input for remote set point control Select one of two configurations 10 Vdc or 4 20 mA dc Control Outputs Isolated analog output for set point control Output drives external Firing Circuit Rectifier Bridge Select one of three configurations 10 Vdc 0 10 Vdc or 4 20 milliamperes dc Meter Drive...

Page 4: ... from 0 90 in 1 increments time to reach nominal value is adjustable from 1 7 200 s in 1 s increments Sequence of Events Recording Events are time and date stamped and stored in volatile memory 127 event capacity 50 ms scan interval SER can be triggered by input output status changes alarms or system operating status changes Data Logging Oscillography Stores 6 records with up to 6 variables per re...

Page 5: ... Includes a two step limiter with a definite time delay for the higher limit level adjustable between 0 and 60 s Summing point type limiter with PI control loop Protection Functions Field Overvoltage Range 1 to 2000 Vdc time delay 0 2 to 30 s dual setting groups Field Overcurrent Range from 0 1 to 9 999 Adc time delay 0 1 to 20 s dual setting groups Generator Undervoltage Range from 0 to 34 500 Va...

Page 6: ...hile a slower controller can provide improved damping of first swing oscillations with the PSS off line Optional Power System Stabilizer The DECS 400 may be purchased with an integral Power System Stabilizer function that duplicates the excellent performance of the Basler PSS 100 Power System Stabilizer without the complications of an additional control device The PSS provides damping for local mo...

Page 7: ...on The DECS 400 has provisions for paralleling two or more generators using reactive droop or for using reactive differential compensation with the addition of an external current transformer with secondary currents of 1 or 5A ac The current input burden is less than 1VA so existing metering CTs can be used Inputting a negative value for droop provides Line Drop Compen sation to offset line or tra...

Page 8: ...and timer gates Inputs to the logic are in the form of discrete information including switching inputs system status data protection status data limiter status data alarm status data and PSS status data The outputs of the logic module can be used to control the relay outputs as well as various other functions inside the DECS such as control functions start stop mode select etc protection functions...

Page 9: ... for an external Dynamic System Analyzer DSA and associ ated transducers Communications DECS 400 comes complete with Windows based PC software designed to make the programming and cus tomization of the DECS 400 easy and fast The software includes a PID selection program that allows the user to select stability settings quickly and easily in a user friendly format The PC software has monitoring scr...

Page 10: ...ystem setup and testing As shown in the Protection screen below left choices are made using drop down screens and parameters are familiar Reminders are also provided at the bottom of the screen for input units and available parameter range Tabs identify general functions and related functions are on adjacent pages As shown on the Underexcitation Limiter Screen below right graphics are also used to...

Page 11: ...ting can also be performed using screens such as the Test Signal screen which can initiate pre programmed tests that may be monitored using the Real Time Monitoring function illustrated in the Analysis screen above right BESTCOMS for the DECS 400 also incorporates greater Windows functionality as shown in the screen shot below The screen simultaneously displays the systems status and alarms window...

Page 12: ...re 4 Front Panel Cutout Dimensions front panel mounting bracket Figure 3 Dimensions Isolation Transducer DECS 400 U PSS 1 Integrated power system stabilizer 2 None POWER SUPPLY L 24 48 Vdc C 125 Vdc 120 Vac CURRENT SENSING 1 1 A CT secondary 5 5 A CT secondary BATTERY BACKUP U Battery backup for real time clock MODEL NUMBER NOTE Effective January 2008 battery backup feature is standard Printed in ...

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