DECS-400 Digital Excitation Control System
3
SPECIFICATIONS, continued
Generator Current Sensing
Single or three phases; separate cross-current compensation input. 1 A ac or 5 A ac
nominal.
Sensing Burden
Voltage: <1 VA per phase. Current: <1 VA. Parallel Compensation: <1VA.
Field Voltage and Current
Field current and voltage values are provided by the Isolation Module.
Isolation Module
Power +5 Vdc, ±12 Vdc from DECS-400.
Five field voltage sensing ranges: 63 Vdc, 125 Vdc, 250 Vdc, 375 Vdc, and 625 Vdc
Output: 0.9-9.1 Vdc (5.0 Vdc = zero field volts)
Two nominal shunt ranges: 50 mVdc and 100 mVdc
Output: 2.0-9.5 Vdc (2.0 Vdc = zero field current)
Contact Inputs
Sixteen contact inputs accept dry switch/relay contacts or open-collector outputs from a PLC. There are six fixed-
function contact inputs and 10 programmable contact inputs. Interrogation Voltage: 12 Vdc.
Fixed Function Inputs
• AVR*
• FCR*
• Lower**
• Raise** • Start*
• Stop*
*Functions activated by a momentary input.
**Functions active only when corresponding contact input is active.
Programmable Inputs
Any of the 10 programmable inputs can be programmed with the following functions. However, these are normally
preassigned by selecting one of the preprogrammed logic schemes.
• 2nd PID settings
• Pre-Position
• Reactive Droop Compensation Enable
• PSS Enable
• PSS Motor Pump/Generator Mode
• PSS Parameters Set Selection
• Phase Rotation
• Unit/Parallel Operation (52 L/M)
• Var/Power Factor Enable (52 J/K)
• Secondary Enable
• 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 Drivers
Two programmable 4 to 20 mA analog meter drivers. Meter side isolated from DECS-400. Programmable to meter
field voltage or current, generator voltage or current, bus voltage, generator or bus frequency, active power,
reactive power, apparent power, power factor, field temperature, tracking error, position indication and PSS
parameters. 64 selectable parameters in all.
Contact Outputs
Two dedicated contact outputs and six programmable contact outputs.
Make 30 A for 0.2 seconds per IEEE C37.90; Carry 7 A continuous. Break (Resistive or Inductive) 0.3 A at 120 Vdc
or 250 Vdc (L/R = 0.04 maximum)
Dedicated Outputs
Programmable Outputs
(All programmed through integrated logic; however,
• Watchdog
• DECS-400 Status
they are normally preassigned when using one of the
• On/Off
• Active Limiter Functions
pre-programmed logic schemes.)
• Active Alarms
• Active Protective Functions
Communication Ports
COM 0
RS-232 front panel female DB-9, 1200-19200 Baud, 8N1 Full Duplex, ASCII commands
COM 1
RS-485 rear panel screw terminals, 4800-19200 Baud, 8N1 Half Duplex, ASCII commands
COM 2
RS-485 rear panel screw terminals, 4800-19200 Baud, 8N2 Half Duplex, Modbus™ protocol
J1
FCC Part 68 approved modem, rear panel RJ-11
RJ-45
Ethernet, Modbus TCP Protocol, 10 base T
