INTRODUCTION

The EDM-200 Exciter Diode Monitor connects to the exciter field circuit

and monitors the output of the brushless exciter power semiconductors.

The EDM-200 can detect the failure of a power rectifier in the brushless

exciter which fails in either the open or shorted mode.

A set of Form C contacts provides alarm annunciation. A bar graph display

enables easy onsite calibration and monitoring of EDM-200 operation.

FUNCTIONAL DESCRIPTION

EDM-200 functional description is illustrated in Figure 3 and described

in the following paragraphs.

Input Amplifier

Resistor R is connected in series with the negative lead to the exciter

field. The small voltage drop developed across R is amplified by the

input amplifier to approximately 1 volt when the generator is unloaded.

During various load conditions, the amplifier output will increase from 1

volt to about 4 volts.