DECS-200 Functional Description i
SECTION 3 • FUNCTIONAL DESCRIPTION
TABLE OF CONTENTS
SECTION 3 • FUNCTIONAL DESCRIPTION............................................................................................ 3-1
INTRODUCTION ....................................................................................................................................3-1
FUNCTION BLOCK DESCRIPTIONS ...................................................................................................3-1
Contact Input Circuits .........................................................................................................................3-2
Start................................................................................................................................................. 3-2
Stop ................................................................................................................................................. 3-2
AVR (Automatic Voltage Regulation)..............................................................................................3-2
FCR (Field Current Regulation) ...................................................................................................... 3-2
Raise ............................................................................................................................................... 3-2
Lower............................................................................................................................................... 3-2
PRE-P (Pre-Position) ...................................................................................................................... 3-2
52L/M (Unit/Parallel) ....................................................................................................................... 3-2
52J/K (Var/Power Factor Enable) ................................................................................................... 3-3
SECEN (Secondary Enable)........................................................................................................... 3-3
ALRST (Alarm Reset) .....................................................................................................................3-3
Analog Inputs...................................................................................................................................... 3-3
Generator Voltage Sensing Ranges ............................................................................................... 3-3
Generator Voltage (V
CA
) ..................................................................................................................3-3
Generator Voltage (V
AB
)................................................................................................................... 3-4
Bus Voltage (BUS V
CA
) .................................................................................................................... 3-4
Phase B Line Current...................................................................................................................... 3-4
Cross-Current Loop Input................................................................................................................3-4
Accessory Input (Remote Setpoint Control).................................................................................... 3-4
Field Current and Field Voltage ...................................................................................................... 3-4
Operating Power.................................................................................................................................3-4
Control Power ..................................................................................................................................... 3-4
Analog-to-Digital Converter (ADC) ..................................................................................................... 3-5
Microprocessor ................................................................................................................................... 3-5
Digital Signal Processor (DSP)...........................................................................................................3-5
Operational Settings ........................................................................................................................... 3-5
Watchdog Timer .................................................................................................................................3-5
Real-Time Clock ................................................................................................................................. 3-5
Pulse-Width Modulated (PWM) Output ..............................................................................................3-5
Relay Output Circuits.......................................................................................................................... 3-5
Programmable Outputs ................................................................................................................... 3-5
Watchdog Output ............................................................................................................................ 3-6
On/Off Output..................................................................................................................................3-6
Communication................................................................................................................................... 3-6
Memory Circuits.................................................................................................................................. 3-6
Protection Functions ........................................................................................................................... 3-7
Field Overvoltage ............................................................................................................................ 3-7
Field Overcurrent ............................................................................................................................3-7
Generator Overvoltage.................................................................................................................... 3-8
Loss of Sensing...............................................................................................................................3-8
Below 10 Hertz ................................................................................................................................ 3-8
Loss of Field .................................................................................................................................... 3-8
Exciter Diode Monitor (EDM) .......................................................................................................... 3-8
Exciter Diode Monitor Settings........................................................................................................ 3-9
SOFT START ......................................................................................................................................... 3-9
LIMITER FUNCTIONS ......................................................................................................................... 3-10
Underfrequency Limiter ....................................................................................................................3-10
Volts per Hertz Ratio Limiter............................................................................................................. 3-11
Overexcitation Limiter (OEL) ............................................................................................................ 3-11
Summing Point OEL...................................................................................................................... 3-11
Takeover OEL ...............................................................................................................................3-12
On-Line/Off-Line OEL Options...................................................................................................... 3-12
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