Complete Guide to Diesel Generator Sets Voltage

In today's society, the stability of power supply is crucial for both industrial production and daily life. Diesel generator sets, as a reliable backup power source, play an indispensable role in many situations. However, many users often encounter voltage instability issues when using diesel generator sets, which not only affect normal equipment operation but may also cause significant economic losses. This article will provide a detailed introduction to voltage stability issues in diesel generator sets and explain how proper maintenance and operation can ensure stable operation.

A diesel generator set is a device that uses diesel fuel and converts engine work into electrical energy through a generator. According to different output voltages, diesel generator sets can be divided into several common types, each with specific application scenarios.

This type of diesel generator is usually used in small places, such as homes, small shops, or temporary construction sites. Its output voltage is 220V, with a frequency of 50Hz, classified as a custom product. Manufacturers have pre-adjusted the generator's output wiring, allowing users to use it directly. This small diesel generator generally uses a single-cylinder engine, suitable for situations requiring long-term 220V operation.

A 380V 50Hz diesel generator is the most widely used type in industrial fields. It is typically used in factories, hotels, mines, construction sites, etc., adopting a three-phase four-wire supply system. This type of generator has a larger power output and can meet the electrical demands of high-power industrial equipment. It is important to note that when using 220V voltage, it should not always be connected to the same phase, as this may cause phase imbalance. The correct approach is to use different phases sequentially, for example, U-phase and N-phase in the morning, V-phase and N-phase in the afternoon. For long-term 220V usage, it is recommended to ask the manufacturer to adjust it in advance to avoid phase imbalance issues.

The output voltage of high-voltage diesel generators is usually 10kV, 6.3kV, etc., suitable for large mining areas, hospitals, and other locations with high power demands. These generators typically have large power capacities and often require multiple units to operate in parallel, with capacities reaching several thousand kilowatts. High-voltage diesel generators are also custom-produced according to specific user requirements.

The voltage stability of diesel generator sets directly affects their output power and the normal operation of equipment. For enterprises that rely on diesel generator sets to generate economic benefits, unstable voltage may lead to serious economic losses. For example, unstable voltage may cause equipment to malfunction or even be damaged, affecting production efficiency and product quality.

Excitation System Faults: Unstable excitation voltage or poor brush contact is one of the main causes of voltage instability. Users can check the excitation winding and excitation power components, including rectifier diodes, SCRs, and other resistive/capacitive components. Poor contact in adjustable potentiometers may also cause unstable voltage, so users should pay attention to maintenance during daily operation.

Excessive or Frequent Load Changes: When the diesel generator set bears a heavy load or when large electrical equipment on the load starts frequently, voltage fluctuations may occur. This is because the generator cannot adjust its output voltage in time to accommodate load changes.

Voltage Regulator Faults: Damage to the voltage regulator components can also cause voltage instability. The voltage regulator ensures that output voltage remains within the set range, and if it malfunctions, the voltage will fluctuate.

Fuel System Issues: Poor fuel flow in the generator set can cause engine speed fluctuations, affecting voltage stability. Additionally, low-quality fuel may result in incomplete combustion, impacting generator output power and voltage stability.

Cooling System Failures: Overheating may reduce generator output voltage. Therefore, it is crucial to regularly inspect the cooling system, including the water pump, radiator, and coolant.

Electrical Connection Problems: Loose or corroded electrical connections can cause unstable current transmission, leading to voltage fluctuations. Ensuring all electrical connections are secure and free of corrosion is an important measure for maintaining voltage stability.

Voltage instability not only affects normal equipment operation but may also damage equipment, increasing maintenance costs. For example, excessive voltage may burn electronic components, while low voltage may prevent equipment from starting or operating normally. Additionally, voltage instability may reduce production efficiency and product quality, causing economic losses for enterprises.

Proper and stable voltage is key to ensuring the normal operation of diesel generator sets. During generator operation, voltage regulation is a critical process. The following provides detailed steps for generator voltage regulation:

Ensure Generator is Stopped: Before adjusting voltage, ensure the generator is completely stopped and disconnected from the grid.

Prepare Necessary Tools: Prepare a multimeter, screwdriver, and other tools for voltage measurement and adjustment.

Locate the Voltage Adjustment Screw: According to the generator model and manufacturer requirements, locate the voltage adjustment screw on the control panel.

Start the Generator: Loosen the adjustment screw with a screwdriver, and set the multimeter to voltage measurement mode before starting the generator.

Adjust the Voltage: Turn the adjustment screw counterclockwise to lower the voltage or clockwise to raise it. Monitor the multimeter until voltage stabilizes within the specified standard range.

Secure the Adjustment Screw: After reaching the appropriate voltage range, tighten the adjustment screw to prevent accidental movement.

Restart the Generator: Turn off the generator, wait a few minutes to ensure voltage stability, then restart it and measure the voltage again to confirm stability. If voltage remains unstable or outside the standard range, readjust as needed.

Reconnect to the Grid: After voltage adjustment, reconnect the generator to the grid to ensure normal operation and stable output voltage.

Voltage drop refers to a sudden decrease in generator output, commonly occurring under full load. Voltage drop may prevent equipment from operating properly or even cause damage. Understanding the causes of voltage drop and taking corresponding measures is essential.

Excessive Load: When the diesel generator set reaches maximum load, voltage drop increases exponentially, as the generator cannot meet the power demands of all equipment.

Mechanical Issues: Fuel shortage, clogged fuel filters, and injector problems can reduce engine speed, affecting voltage output.

Electrical Connection Problems: Loose or corroded connections can destabilize current transmission, causing voltage drops.

Select Appropriate Generator Power: Ensure the purchased generator matches actual power requirements. If load is too high, choose a higher-capacity generator or increase total power via parallel operation.

Regular Maintenance: Check and maintain the fuel system, cooling system, and electrical connections regularly to keep the generator in good operating condition.

Avoid Underloading: Underloading can cause serious damage. Low loads force the generator to work harder to reach operating temperature, stressing glow plugs and the diesel engine. Underloading produces low cylinder pressure, reducing efficiency and causing soot buildup, which can quickly block cylinders and stop generator operation. Generators should ideally run at 70–100% load.

To ensure voltage stability, routine maintenance is essential:

Check Fuel Quality Regularly: Low-quality fuel can lead to incomplete combustion, affecting generator output power and voltage stability.

Inspect Cooling System: Regularly check pumps, radiators, and coolant status. Cooling system failure may cause overheating, affecting voltage stability.

Check Electrical Connections: Loose or corroded connections can cause voltage fluctuations. Ensure all connections are secure and free of corrosion; repair or replace as needed.

Inspect Excitation System: Aging excitation systems may cause voltage regulation to be insensitive, leading to fluctuations. Regularly check excitation windings and components and repair or replace if faulty.

Use Load Reasonably: Sudden load changes, such as switching large electrical equipment on or off, can prevent the generator from adjusting voltage promptly, causing fluctuations. In industrial environments, frequent load changes make voltage stability challenging. Properly plan equipment usage to minimize voltage swings.

The voltage stability of diesel generator sets is crucial for normal operation and equipment safety. By understanding the causes of voltage instability and taking appropriate measures, generator efficiency and reliability can be effectively improved. Regular maintenance and proper operation are key to ensuring voltage stability. This article aims to help you better understand and maintain diesel generator sets, ensuring stable operation across various applications and providing reliable power for production and daily life.