Many years ago, all engine oils were single-grade engine oils. Modern generator sets generally use multiple grades of oil, and the grade is represented by two numbers, connected by the letter “W” in the middle. The first number indicates the performance under cold conditions, and the second number indicates the viscosity under warm conditions. Certain applications, such as gas generator sets, or places where the temperature difference between hot and cold operation is small, will still use single-grade oil.
The formula of generator set oil is formulated according to specific operating conditions. Under normal circumstances, the generator set, as well as the base oil and additives commonly used in transmission or hydraulic systems are mixed to achieve the required lubrication function that can cope with various operating environments. Using the right oil can bring obvious benefits to your generator set, such as smoother operation, longer generator set life and better return on equipment investment.
The function of generator set oil is to protect the generator set from wear by reducing the friction between moving parts. Other functions include: cooling and lubricating the surface, preventing corrosion and rust, preventing the formation of deposits, removing contaminants and neutralizing acid degradation. In addition, the oil must be able to provide lubrication over a wide operating temperature range.
Generator oil is composed of two major parts-base oil and additives. The blending formula of each oil must be able to meet the requirements of regulations and the standard performance of lubricants required by specific applications, such as generator sets, transmissions or hydraulic systems.
The base oil can be mineral oil, or semi-synthetic or synthetic oil. Non-road diesel generator sets generally use mineral oil. Semi-synthetic and synthetic engine oils are often used in gasoline generator sets, such as automotive generator sets, because longer maintenance intervals and stricter operating conditions require more refined engine oils. But these more refined base oils are much more expensive.
The combination of additives is the key to determining whether the oil only meets API standards or can provide significantly better lubrication performance. These additives can enhance the chemical and physical properties of the oil, thereby improving the performance of the lubricant, which is beneficial to the operation of the generator set.
The additives used in generator oils include 10 to 15 different types of complex compounds. The proportion of additives in the oil can be as high as 25%, depending on the quality and application of the oil.
Each additive must be carefully selected to ensure compatibility with the base oil and other additives in order to avoid adverse negative effects after mixing. For example, detergent is added to keep the inside of the generator set clean, but it may cause a lot of foam, which prevents the formation of a good oil film and reduces the amount of oil circulating in the oil circuit. Therefore, the ratio of detergent and defoamer must be balanced, which is very critical.
Each additive has its specific function, including:
• Detergent can keep the inside of the generator set clean.
• The dispersant can keep the impurities in the engine oil suspended so that they can be effectively removed when the engine oil is changed or filtered out by the engine oil filter.
• Anti-wear agents can enhance the lubricating properties of the base oil and form a protective film on moving parts.
• Preservatives and rust inhibitors protect the generator set from sulfur in the engine oil.
• Antioxidants can prevent engine oil from oxidizing; once the engine oil is oxidized, it will increase the viscosity of the engine oil, form sludge and deposits, and even decompose the base oil and cause corrosion.
Operating temperature
Viscosity index improver is an important additive. The viscosity of the oil determines the flow rate of the oil and changes with the temperature: as the temperature rises, the oil becomes thinner and flows more smoothly. The challenge faced by generator set oil is how to maintain proper flow characteristics to protect the generator set during the entire process when the temperature is low when the generator set starts, and the temperature gradually rises during the operation of the generator set.
Viscosity index
Viscosity index improvers help ensure that the generator set oil will not be too thick in cold weather, because too thick engine oil may not circulate properly in the oil circuit when starting, causing the generator set to lack protection and wear. At the same time, the viscosity index improver can also ensure that the oil film will not become too thin at operating temperatures in hot climates, because such conditions will also cause wear. The Society of Automotive Engineering (SAE) is responsible for the development of oil viscosity ratings. The higher the viscosity value, the thicker the oil and the harder it is to flow.
Post time: Jul-28-2021