MarelliMotori M8B 250

Questions and Answers

G
Geoffrey PatelAug 5, 2025
Why is the voltage lower than rated on my MarelliMotori Portable Generator?
- T
  tandersonAug 5, 2025
  If the output voltage of your MarelliMotori Portable Generator is between 50% and 70% of the rated value, there are several potential causes. First, verify that the engine speed (RPM) and frequency are at the correct levels. Next, adjust the voltage potentiometer until the voltage reaches the rated value. Also, check the fuse and replace it with a spare if it's blown. Lastly, a faulty regulator could be the problem, so disconnect and replace the AVR.
B
Brian VazquezAug 15, 2025
Why is the voltage unstable on my MarelliMotori M8B 250?
- R
  Ryan BerryAug 15, 2025
  If you're experiencing unstable voltage with your MarelliMotori Portable Generator, the issue could stem from a few sources. Variations in the diesel engine's RPM could be the cause; check the RPM uniformity and the diesel engine governor. Another possibility is an improperly set stability potentiometer; try adjusting the AVR's stability potentiometer. Finally, a faulty regulator might be to blame, in which case you should replace the AVR.
Y
yjonesAug 25, 2025
How to fix too high voltage on my MarelliMotori M8B 250?
- J
  Joseph WaltersAug 26, 2025
  If the voltage output of your MarelliMotori Portable Generator is too high, it could be due to a potentiometer V that is unset. Try rotating the potentiometer until the voltage reaches the rated value. If that doesn't solve the problem, the regulator may be faulty, and you should replace the AVR.

Summary

1. Description

2. Transport and Storage

3. Installation and Commissioning

3.1 Check Before Installation

Verify nameplate data and ensure installation complies with recommendations before proceeding.

3.2 Insulation Test

Perform insulation resistance test on stator windings, especially after long storage periods.

3.3 Balancing

Rotor is dynamically balanced with a half-key as per IEC 34-14 standard.

3.4 Installation Conditions

Install in a ventilated room, ensuring clear air inlet/outlet and access for maintenance.

3.5 Alignment

Ensure accurate alignment with the driving machine to prevent vibrations and damage.

3.6 Electrical Connection

Connects generator terminals for star series or parallel configurations as per diagrams.

3.7 Commissioning

Perform pre-startup checks including insulation, alignment, and electrical connections.

4. Maintenance

4.1 Inspection and Maintenance Intervals

Schedule inspections based on operating hours, ambient conditions, and prime mover maintenance.

4.2 Maintenance of Bearings

Details lubrication intervals and recommended grease types for generator bearings.

4.3 Dismantling Operations

Provides safety precautions and steps for safely disassembling generator components.

4.4 Reassembly Operations

Details reassembly steps, emphasizing care and use of specific materials like LOCTITE.

5. Voltage Regulator

5.1 Thermal Protection Device

Describes the thermal protection connected to auxiliary terminals for alarm or intervention.

5.2 Rheostat for Remote Voltage Setting

Explains how to connect an external rheostat for adjusting voltage from a control panel.

5.3 Instructions for Manual Control of Generators

Details manual control system usage when the primary AVR fails, requiring a 24V DC supply.

5.4 Overboosting Device VARICOMP

6. Trouble Shooting and Repairs

7. Spare Parts - Nomenclature

8. Disposal

Rotating Rectifier

Instructions for Application of Pressure-Sensitive Name Plate