DESCRIPTION

The microprocessor based DECS-200 is a total excita

tion control system in one enclosure. It contains all the

functionality necessary to limit, control, and protect a

generator from operating outside of the machine’s

capability. A feature of DECS-200’s sophisticated

design allows the nonactive control mode within the

unit to follow the active mode, permitting bumpless

transfer between modes. The optional external tracking

feature also allows for unit-to-unit communication,

permitting autofollowing and transfer between DECS

200 units. It can also communicate to a PC via the front

panel RS-232 port for local programming and metering,

and it can communicate via Modbus™ protocol via the

side RS-485 port for communications up to 4000 feet

away from the DECS-200 unit. The DECS-200 has all

the features, functionality, flexibility and programmabil

ity expected from a state-of-the-art microprocessor

based product.

APPLICATIONS

The DECS-200 is an excitation control system used to control 

the output voltage, vars or power factor of a synchronous

generator by varying or controlling the amount of dc excitation

applied to the generator’s exciter field.

The DECS-200 is suitable for virtually any size machine.

One DECS-200 Digital Excitation Control System can accommodate 32Vdc, 63Vdc, or

125Vdc applications up to 15Adc. This unique flexibility provides precision control of

generators of virtually any size. The DECS-200 also incorporates a pulse width modulated

power stage, which improves system performances in non-linear load applications.

FEATURES

• Microprocessor-based design

• True RMS sensing, single or three phase

• 32Vdc, 63Vdc, and 125Vdc outputs at 15Adc

• 0.25% Voltage Regulation Accuracy

• Setup from front panel HMI or by PC with Windows® setup software included

• 20 standard stability selections

• User customizable stability selection

• Paralleling compensation

• Underfrequency compensation or V/Hz Ratio Limiter

• Soft start buildup

• Field Current Regulation Mode (Manual Mode)

• Autotracking between operating modes and between DECS-200 units

(optional)

• Minimum Excitation Limiter (Internally generated or customizable)

• On and off-line Maximum Excitation Limiters

• Stator Current Limiter

• Var and Power Factor Controllers

• Exciter Diode Monitoring (EDM)

• Sequence of Events Recording

• Oscillography

•Voltage Matching

•Eight (8) generator protection features

•Programmable output contacts

•Front panel backlit LCD display

•Front panel mounted RS-232 and side RS-485

communications ports

•Modbus™ protocol for RS-485 input allows

communications up to 4000 feet away

•<1% metering accuracy for 12 generator parameters

•Remote set point control via:

– Contact inputs

– Proportional control via ±10Vdc or 4-20mA

– Communications inputs RS-232 (ASCII) or RS-485(Modbus™)

•Meets C37.90.1-1989 for Surge Withstand and Fast Transient

•UL recognized, CSA certified, CE compliant, DNV certified,

GOST-R certified, Byelorussian certified

•U.S. Patent Number 5.294.879

The DECS-200N is a multi-microprocessor based Negative

Forcing Digital Excitation Control System designed into one

complete compact package. This space-saving design

consists of all the functionality needed to control, limit and

protect a generator from operating outside the machine’s

capability. This is accomplished by the DECS-200N’s

impressive control algorithm coupled with a versatile 20Adc

6 SCR power bridge. The input of the power bridge can be

fed by a 50 to 500 Hz, single or three phase voltage source,

depending on the desired excitation levels it is intended to

support.

DESCRIPTION

The DECS-200N also incoporates four control modes of

operation: Automatic Voltage Regulation (AVR), Field

Current Regulation (FCR, Manual), Volt Amp Reactive (Var)

and Power Factor (PF) control. In addition to these control

modes, the DECS-200N provides the ability for all non-active

control modes to follow the set point of the active mode,

permitting bumpless transfer between any other modes. For

applications requiring redundancy, the DECS-200N can

communicate unit-to-unit, allowing the backup DECS-200N

to automatically follow the active unit’s set point in the event

it is necessary to switch to the backup DECS-200N. Commu

nications with a PC is possible via a front panel RS-232 port

for local programming and metering. Provisions for remote

control are also available using contact inputs and the RS

485 port via Modbus protocol. The DECS-200N offers all of

the features, functionality, flexibility, and programmability for

use in new installations and in retrofit applications.

FEATURES

• Multiple microprocessor-based design

• True RMS sensing, single or three phase

• ±0.25% Voltage Regulation Accuracy

• 63 Vdc and 125 Vdc output capability up to 20 Adc continuous

• Built-in 6 SCR power bridge

• Negative field forcing

• Highly compact design

• High initial response

• Soft start buildup

• Var and Power Factor operating modes with Autotracking

• Autotracking between operating modes and between dual DECS-200Ns

• On and off-line Overexcitation Limiter

• Customizable Underexcitation Limiter

• Stator Current Limiting

• Underfrequency compensation or V/Hz Ratio Limiter

• Field flashing control provisions

• Paralleling provisions

• Generator Protection

• Exciter Diode Monitoring (EDM)

• Oscillography and Sequence of Events Recording

• Voltage Matching

• 5 Programmable output contacts

• Modbus™ protocol via RS-485 communications

The DECS-200N is a very compact Negative Forcing Digital Excitation Control System.

This compact design accommodates 63 Vdc and 125 Vdc applications up to 20 Adc

continuously. The on-board six-thyristor controlled rectifier bridge offers the highest

system performance possible, making the DECS-200N ideal for providing exceptional

system response, which makes it suitable for applications requiring power system

stabilizers.

APPLICATION

The DECS-200N is a highly responsive negative forcing excitation

control system used to control the output voltage, vars, or power

factor of a synchronous generator by automatically adjusting the

amount of dc excitation being applied to the generator’s exciter field.

Due to its negative forcing capabilities, the DECS-200N is ideal for

virtually any size system that demands exceptional system response

and/or requires Power System Stabilizers.