1. INTRODUCTIONThis User Manual provides general installation and use information regarding the Marelli Motori regulator whose code is reported on the cover and inside the document, mounted on Marelli Motori generator types indicated in Chap. 3.Before starting the generator and performing any type of regulation operation, carefully and completely read all of the instructions contained in this manual.IMPORTANT NOTE: This User Manual not intended to cover all of the possible application or installation variations nor to provide data or information to support every possible contingency. The connection diagrams provided with the generator, its Use and Maintenance Manual and any additional information provided by qualified Marelli Motori technical personnel supplements and completes this manual. In particular, the diagrams reported in this document provide only an example of the connection and operation mode for the device; these do not cover all possible application cases and are not a substitute for the connection diagrams normally provided with the generator.If further application information becomes necessary, please contact Marelli Motori Services.2.APPLICATIONThe M31FA600A MEC-20 voltage regulator is suitable for synchronous generators constructed by Marelli Motori.NOTE: For information on compatibility with different sizes or series of synchronous generators other than those indicated above, contact Marelli Motori Services3. TECHNICAL SPECIFICATIONSThe M31FA600A voltage regulator is a micro-processor device with pulse-width modulation (PWM) output stage, and can be calibrated using potentiometers. The circuit board is resin-bonded in order to maintain a high degree of operational reliability even in difficult environmental conditions (high levels of humidity, dust, a salty atmosphere) and in the presence of vibrations.