Professional Installation Technical Document for 28V 240A Generator

I. Scope of Application and Technical Parameters

1. Application Scenarios

2. Core Technical Parameters

II. Pre - installation Preparation

1. List of Tools and Materials

2. Safety and Environmental Requirements

• Safety Protection: Wear insulating gloves, safety goggles, and non - slip shoes to avoid high - voltage electric shock and mechanical injuries.

• Environmental Conditions: No flammable and explosive gases, dust concentration ≤10mg/m³, and ambient temperature ranging from -10℃ to +40℃.

• Equipment Status: The engine shall be shut down and powered off (disconnect the negative pole of the storage battery), and the temperature of the cooling system shall be ≤40℃.

3. Inspection of Components

• Generator Appearance: No cracks or deformation; wiring terminals shall be free of oxidation and looseness; the pulley shall rotate flexibly without jamming.

• Electrical Performance: Use a megohmmeter to measure the insulation resistance between the stator winding and the housing, which shall be ≥10MΩ. The rotor winding resistance shall comply with the manufacturer's specifications (usually 0.5 - 1.5Ω).

• Supporting Components: The mounting bracket shall be free of deformation and corrosion; the belt shall be free of aging and cracks; the bolt specifications shall match the generator mounting holes.

III. Step - by - Step Installation Process (Complying with the SAE J1995 Installation Standard)

Step 1: Locate the Mounting Bracket

1. Clean the engine mounting surface and the generator mounting base to remove oil stains and rust (using sandpaper or cleaning agent).

2. Place the generator on the mounting bracket and align the mounting holes (alignment deviation ≤0.5mm). Ensure that the generator pulley and the engine crankshaft pulley are in the same plane (flatness error ≤0.3mm).

3. Manually insert the mounting bolts (with flat washers and spring washers) and initially tighten them (torque: 10 - 15N·m), without full fastening for the time being.

Step 2: Install the Drive Belt

1. Install the belt along the engine belt transmission path (pay attention to the belt direction and avoid reverse installation).

2. Adjust the generator position (via the adjusting bracket or tensioner) and measure the tension with a belt tension gauge:

• Multi - ribbed belt: Tension value ranges from 400N to 600N (corresponding deflection: 10 - 15mm under 100N pressure).

• V - belt: Tension value ranges from 300N to 500N (corresponding deflection: 15 - 20mm under 100N pressure).

3. After adjusting the tension to the required value, fasten the mounting bolts. Tighten them evenly in three steps to the specified torque (35 - 45N·m) and verify with a torque wrench.

Step 3: Electrical Wiring (Critical Safety Step)

1. Confirm the definition of the generator wiring terminals (refer to the manufacturer's manual):

• B+ (Output Terminal): Connect to the positive pole of the storage battery or the main power supply of the distribution box.

• D+ (Field Terminal): Connect to the voltage regulator or ignition switch.

• E (Ground Terminal): Connect to the engine block or frame (ground resistance ≤0.05Ω).

2. Wiring Operations:

• Strip the insulation layer of the wire (length: 5 - 8mm) to expose the copper core without oxidation.

• Terminal connections shall adopt crimping or welding methods (welding temperature ≤350℃, welding time ≤5s). Wrap the connection points with insulating tape.

• An fuse shall be installed at the B+ terminal (capacity: 250 - 300A, fusing speed ≤10ms). The wire cross - section shall be ≥35mm² (copper core) and the wire length shall be ≤1.5m.

3. Ground Connection: Select a paint - free and rust - free metal surface on the engine block. Fasten the ground wire with bolts (torque: 15 - 20N·m) to ensure good contact.

Step 4: Mechanical and Electrical Inspection

1. Mechanical Inspection

• Rotate the pulley by hand to check for no jamming or abnormal noise. Ensure that the belt fits well with the pulley grooves (no slipping gap).

• Check that the gap between the generator and surrounding components is ≥20mm (to avoid vibration interference).

2. Electrical Inspection

• Use a multimeter to measure the resistance between the B+ terminal and the ground, which shall be infinite (indicating no short circuit).

• Check that all wiring terminals are free of looseness and exposure, and the insulation wrapping is intact.

Step 5: Commissioning and Test Run

1. Connect the negative pole of the storage battery, turn on the ignition switch (without starting the engine), and measure the voltage at the D+ terminal, which shall be equal to the storage battery voltage (about 24V).

2. Start the engine and let it run at idle speed (600 - 800rpm). Measure the voltage at the B+ terminal, which shall be 27.5 - 29.5V (complying with the ISO 8854 standard).

3. Gradually increase the engine speed to the rated speed (e.g., 2000rpm). Measure the output current, which shall be ≤240A (no overload). Observe that the generator has no abnormal heating or noise.

4. After 30 minutes of operation, conduct the following inspections:

• The belt tension does not decrease significantly (tension deviation ≤10%).

• The temperature of the wiring terminals is ≤60℃ (measured with an infrared thermometer).

• The temperature of the generator housing is ≤90℃ (meeting the SAE J1940 heat dissipation requirements).

IV. Installation Precautions (Key Risk Control Points)

1. Torque Control: The mounting bolts must be fastened to the specified torque. Loose bolts will cause vibration and abnormal noise, while excessive tightening will damage the threads or the generator housing (referring to the GB/T 16823.3 torque standard).

2. Electrical Safety

• Strictly distinguish between the positive and negative poles during wiring. It is forbidden to directly ground the B+ terminal, as this will cause a short circuit and burn out the generator.

• The field terminal (D+) must be connected to the voltage regulator. Direct connection to the storage battery is prohibited, as it will cause the rotor to overheat.

3. Belt Installation

• Do not use tools to pry the belt into the grooves, as this will damage the belt teeth. Instead, adjust the generator position to allow the belt to fit into the grooves naturally.

• The belt model must match the generator power. For a 240A generator, the belt shall have a bearing power of ≥8kW.

4. Grounding Requirements: A separate ground wire must be configured for the generator. Indirect grounding through engine oil, coolant, etc., is prohibited, as it will lead to poor contact and voltage fluctuation.

5. Environmental Adaptation

• For high - temperature environments (≥60℃), an heat shield shall be installed.

• For dusty environments, regularly clean the air inlet of the generator.

• For humid environments, strengthen the waterproof treatment of the wiring terminals (e.g., apply waterproof sealant).

VI. References and Authoritative Sources

1. SAE J1940 - 2018 Technical Specifications for Automotive Alternators

2. ISO 8854 - 2017 Reciprocating Internal Combustion Engines - Alternators - Electrical Characteristics

3. GB/T 2820.5 - 2019 Reciprocating Internal Combustion Engines - Part 5: Generators

4. IEC 60034 - 6 - 2021 Rotating Electrical Machines - Part 6: Methods of Cooling

5. Technical manuals of generator manufacturers (e.g., technical manuals for Bosch, Delphi, and Valeo 28V 240A series products)