Basler Electric ECM-2 Excitation Control Module

Introduction

The ECM-2 Excitation Control Module provides the core functions of regulation, input sensing, and

thyristor firing control in a DECS-2100 Digital Excitation Control System. Functions previously provided by

three separate circuit boards in ECS2100 systems are now provided by one compact module. The ECM-2

replaces the Sensor Input Module (SIM), Exciter Control Module (ECM), and Firing Control Interface

Module (FCIM) previously used in ECS2100 systems.

ECM-2 advantages include:

• Fully-enclosed package provides protection of key system circuitry

• Previously-required space for three, separate circuit boards is reduced to one compact module

• The proven reliability of the ECS2100 system design with added functionality:

o Improved thyristor firing accuracy

o Increased number of analog inputs from 12 to 24

o Standard ECM-2 hardware configuration supports up to four power bridges via fiber optic

communications. The expanded fiber optic version can accommodate up to 16 power bridges

o Expanded event recording and data logging capability

o Additional USB port accepts removable storage media for downloading events, data logs,

and alarm logs without the use of a computer

o Cross-current compensation between excitation systems through a built-in communication via

RJ-45 port over Ethernet

o IRIG-B and NTP time synchronization provides synchronized data recording.

o Additional RJ-45. 10BASE-T/100BASE-TX Ethernet port for a dedicated control network

protocol

Functional Description

ECM-2 performs functions previously performed in ECS2100 systems by three, separate modules:

Sensor Input Module (SIM), Exciter Control Module (ECM), and Firing Control Interface Module (FCIM).

The functionality of these modules has been retained with some enhancements.

Sensor Inputs

Twenty-four, high-speed analog inputs (channels) collect data (sensing values) from the generator PTs

and CTs and other analog signal sources through hard-wired inputs. Fiber-optic connections receive

digital signals supplied by the DECS-2100 system Digital I/O Modules. Analog and temperature signals

supplied by the DECS-2100 system Analog I/O Modules are also received through fiber-optic connections

on the isolation transducer card interface. Analog inputs are digitized and provided to the excitation

circuitry for interpretation.

Power Bridge Firing Interface

This portion of the ECM-2 module provides SCR firing commands to the DECS-2100 system Bridge

Control Modules. In turn, each Bridge Control Module controls the level of dc output power supplied by

the corresponding power bridge. Power bridge output is determined by a control signal supplied from the

excitation control circuitry to the firing control logic. To generate the SCR firing signals, the firing control

circuitry creates timing signals that are time- and pattern-synchronized with the monitored, three-phase

PPT voltage. (The PPT voltage is monitored by way of an Isolation Transducer connected to the ECM-2

module’s PPT fiber-optic input.) The firing signals, interspersed with data signals, are transmitted to the

DECS-2100 system Bridge Control Modules via fiber-optic connections.

In its standard configuration, the ECM-2 module can control from one to four sets of Bridge Control

Modules and power bridges. In its optional configuration, up to 16 sets of Bridge Control Modules and

power bridges can be controlled.

In addition to power bridge control, this circuitry processes power bridge alarms received from the Bridge

Control Modules and provides the alarm data to the excitation control logic. Processed alarms include

SCR loss, high power bridge temperature, and low power bridge temperature.