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9440300990 Rev J
Introduction
DECS-250
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Twelve contact outputs
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One, fixed-function output: Watchdog (SPDT configuration)
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Eleven programmable outputs
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Flexible communication
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Serial communication through front-panel USB port
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Modbus communication through RS-485 port or Modbus TCP
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Ethernet communication through an optional copper or fiber optic port
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CAN communication with an ECU (engine control unit), optional AEM-2020 Analog
Expansion Module, or optional CEM-2020 Contact Expansion Module
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Optional PROFIBUS communication protocol
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Data logging, sequence of events recording, and trending
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Optional CEM-2020 Contact Expansion Module provides:
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Ten contact inputs
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Eighteen contact outputs (CEM-2020H) or 24 contact outputs (CEM-2020)
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Customizable input and output functions assigned through BESTlogic™
Plus
programmable logic
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Communication via CAN protocol
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Optional AEM-2020 Analog Expansion Module provides:
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Eight analog inputs
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Eight resistive thermocouple device (RTD) inputs
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Two thermocouple inputs
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Four analog outputs
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Customizable input and output functions assigned through BESTlogic
Plus
programmable
logic
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Communication via CAN protocol
Applications
The DECS-250 is intended for synchronous generator or synchronous motor applications. The DECS-250
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-250 by means of a filtered, switching power module that uses
pulse-width modulation. It is capable of supplying 15 Adc continuously at a nominal voltage of 32, 63, or
125 Vdc. With nominal operating power applied, it has a forcing capability of 30 Adc for 10 seconds.
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-250 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.
Summary of Contents for DECS-250
Page 2: ......
Page 6: ...iv 9440300990 Rev J Revision History DECS 250 ...
Page 16: ...xiv 9440300990 Rev J Contents DECS 250 ...
Page 20: ...4 9440300990 Rev J Introduction DECS 250 ...
Page 28: ...12 9440300990 Rev J Power Stage DECS 250 ...
Page 32: ...16 9440300990 Rev J Voltage and Current Sensing DECS 250 ...
Page 40: ...24 9440300990 Rev J Synchronizer DECS 250 ...
Page 52: ...36 9440300990 Rev J Auxiliary Control DECS 250 ...
Page 56: ...40 9440300990 Rev J Contact Inputs and Outputs DECS 250 ...
Page 84: ...68 9440300990 Rev J Limiters DECS 250 ...
Page 114: ...98 9440300990 Rev J Power System Stabilizer DECS 250 Figure 96 PSS Parameter Settings ...
Page 124: ...108 9440300990 Rev J Stability Tuning DECS 250 ...
Page 126: ...110 9440300990 Rev J Mounting DECS 250 Figure 103 Overall and Projection Mounting Dimensions ...
Page 127: ...9440300990 Rev J 111 DECS 250 Mounting Figure 104 DECS 250 Escutcheon Plate Dimensions ...
Page 198: ...182 9440300990 Rev J Timekeeping DECS 250 ...
Page 210: ...194 9440300990 Rev J CAN Communication DECS 250 ...
Page 304: ...288 9440300990 Rev J Maintenance DECS 250 ...
Page 316: ...300 9440300990 Rev J Specifications DECS 250 ...
Page 334: ...318 9440300990 Rev J Analog Expansion Module DECS 250 ...
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