Basler Electric DECS-200 Digital Excitation Control System

Basler Electric DECS-200 Digital Excitation Control System

This instruction manual provides information about the operation and installation of the DECS-200 Digital

Excitation Control System. To accomplish this, the following information is provided:

• General Information and Specifications

• Controls and Indicators

• Functional Description

• Installation

• Maintenance

INTRODUCTION

The Basler Digital Excitation Control System (DECS-200) is a microprocessor-based control device

intended for generator power management. Programmability of system parameters and regulation

settings enables the DECS-200 to be used in a wide range of applications and provides greater flexibility

in excitation system optimization. The DECS-200 can accommodate generator exciter field requirements

up to 15 Adc continuously in 32. 63. or 125 Vdc applications with one model.

FEATURES

DECS-200 units have the following features and capabilities.

Functions

• Four control modes

o Automatic voltage regulation (AVR)

o Manual or field current regulation (FCR)

o Power factor (PF)

o Reactive power (var)

• Soft start buildup with an adjustable ramp in AVR and FCR control modes

• One adjustment range or pre-position setpoint for each control mode

• Overexcitation limiting (OEL) and underexcitation limiting (UEL) in AVR, var and PF control modes

• Twenty stability selections

• Underfrequency compensation or volts per hertz ratio limiter

• Autotracking between operating modes and between DECS-200 units (optional)

• Automatic transfer to a backup DECS-200 unit (optional)

• Eight generator protection features

o Field overvoltage

o Field overcurrent

o Generator overvoltage

o Generator undervoltage

o Watchdog timer

o Loss of sensing

o Exciter diode monitor (EDM)

o Loss of field

• Generator paralleling with reactive droop compensation and reactive differential compensation

• Data logging and event recording

Inputs and Outputs

• Single-phase rms bus voltage sensing

• Single-phase or three-phase rms generator voltage sensing

• Single-phase generator current sensing (1 or 5 amperes, nominal)

• Analog inputs (±10 Vdc and 4 to 20 mAdc) provide proportional, remote control of the setpoint

• Eleven PLC-compatible contact sensing inputs for system interface

• Separate ac and dc power inputs accommodate redundant operating power sources

• Pulse-width modulated output power stage rated at a maximum of 15 amperes, continuous

• Five output relays for system control or annunciation

o Three programmable output relays

o Two fixed-function output relays

HMI Interface

• Front panel HMI includes pushbutton controls, LED indicators and a backlit, liquid crystal display

(LCD)

• BESTCOMS™ Windows® based software provides easy, fast and accurate setup and control

Three communication ports

o Front RS-232 port for communication with a PC using BESTCOMS software

o Right-side panel RS-232 port for dedicated communication with a redundant DECS-200

o RS-485 communication port for communication with a remote terminal

• Modbus protocol for the RS-485 port allows communication at distances of up to 1.200 meters

(3.937 feet)

Introduction

In the typical application shown in Figure 1-1. the DECS-200 controls the exciter field of a synchronous

generator. Front panel controls, indicators, and serial communication ports using PC software make the

system easy to operate locally or from remote locations. DECS-200 operation, settings, and safety setup

procedures in this manual should be studied before implementing your application. For detailed

application assistance, contact Basler Electric or your local sales representative.

Operating Power

Operating power for the pulse-width modulated (PWM) excitation output is typically obtained from the

generator output through a power transformer. Alternately, operating power can be supplied from a

permanent magnet generator (PMG).

During DECS-200 power-up, an optional ICRM (Inrush Current Reduction Module) prevents damage to

the DECS-200 by limiting inrush current to a safe level. For more information, refer to Section 4.

Installation.

Control Power

If power supply option C (120/125 Vac/Vdc) is selected, a redundant power source can be used with the

DECS-200. (See Figure 1-1.) In this configuration, if one of the two sources fails, the other source will

continue to supply DECS-200 operating power. If power supply option L (24/48 Vdc) is selected, no

redundant power source is available.

Sensing

The DECS-200 senses generator voltage and current through voltage and current transformers. Field

voltage and field current values are sensed internally.

Excitation Limiters

Integrated overexcitation and underexcitation limiters (OEL and UEL) are available for both on-line and

off-line protection.

External Tracking and Transfer Between DECS-200 Units (Optional)

For critical applications, a second DECS-200 can provide backup excitation control. The DECS-200

allows for excitation system redundancy by providing external tracking and transfer provisions between

DECS-200 units. The secondary DECS-200 operating modes can be programmed to track the primary

DECS-200 operating mode. Proper, redundant excitation system design allows for removal of the failed

system. Periodic testing of the backup system must be performed to ensure that it is operational and can