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The insulating oil utilized in the transformer's liquid insulation is an exceptional kind of oil with exceptional insulating properties that are as well as firm at high temperatures. Mineral oil is commonly employed in power transformers based on oil to stop the formation of corona discharge and arcing and to remove the heat generated inside the transformer (i.e. acts as a coolant).
The function of the oil that is insulating is to safeguard the transformer's inner core as well as windings, which are completely submerged by the insulation oil. It is also the duty of the transformer oil to prevent any reaction between oxygen with the insulation, which is composed of cellulose material, thus extending the life that the transformer. The oil used in the transformer's insulation acts as a barrier between the oxygen present in the air and the insulation (cellulose paper) to stop their direct contact and slow down the oxidation process. The quantity of Insulating mineral oil within the transformer is usually assessed using the MOG (Magnetic Oil level Gauge).
The transformer's insulating oil may be examined to find out the health status of the transformer, and hence it is known as the information transmission.
PARTICULARITIES OF TRANSFORMER OIL
The strength of the transformer's insulation oil is determined through the use of certain features of the oil that is used to insulate. The most desirable features (or characteristics) of the transformer's oil used to insulate are:
Electrical characteristics:
Dielectric capability, definitive resistance, dielectric dissipation factor.
Chemical properties:
Acidity, wetness, and sludge content.
Physical characteristics:
Viscosity, pressure, and pressure are interfacial. The importance of flashpoint as well as for point.
Electrical properties of Transformer Insulating Oil
Dielectric Properties of Transformer Oil
The dielectric capacity of transformer oil (dielectric strength of transformer oil) is determined by the breakdown strength (BDV) of the transformer oil. Breakdown strength is defined as the voltage that spark plugs connect between the two electrodes, which are dipped in the oil, separated by a specific distance. A lower BDV value is a sign of the presence of significant amounts of steering and wetness inside the oil. The procedure for evaluating BDV in the mineral insulating oil is to use a mobile BDV computing device that is normally located near the equipment. In the kit, oil is stored inside a pot. Within it, a set electrode is placed. The voltage is then carefully reached between the two electrodes. The voltage applied is controlled by the transformer oil. The oil will be monitored continuously to determine the amount of voltage that triggers flashing firing in the two electrodes. This is the voltage at which the dielectric capacity of the transformer oil that holds the electrodes is damaged. The process may be repeated multiple times, and the measurement is made from the exact fragments of oil. The average of the readings is determined. BDV is the most important determinant of transformer oil because it gauges the health of oil quickly and is able to be measured on the spot without any effort. In the first few years in service, the oil will be dry and clean and provides higher BDV than the oil after being operating for many years that contain water as well as other impurities carrying the.
Definitive Resistance of Transformer Oil -
Another property that is a requirement for transformer oil is its specific resistance, which is identified by measuring the direct resistance between the two sides of a cm3 oil slab. The unit that represents specific resistance is an ohm-cm value at a certain temperature of rundown. It is observed that the temperature of the transformer's insulation oil increases dramatically, as the resistance of the oil that is used to insulate it falls out rapidly. After a prolonged break after the transformer has been placed on charge, the oil's temperature will increase to a normal level however, when the transformer is been fully loaded, its temperature rises up quickly leading to the overloaded state. Therefore, the transformer's oil should have higher resistance at room temperature, and have a desirable amount of resistance in higher temperatures too. So the exact resistance of the oil for the transformer must be determined at temperatures of the minimum as well as maximum values. The most precise value for resistance of transformer oil with a set temperature of 90oC is calculated as 35 x 1012ohm-cm. at 27oC, the value changes to 1500 x 1012 Ohm-cm.
Dielectric Dissipation in Transformer Oil -
Dielectric dissipation factors are also known by another term called loss factor. It's commonly referred to as the delta of the oil used to insulate transformers. If the insulating material is placed between the active area as well as that is the section at the foundation of the electrical apparatus, an aperture current will develop that runs through it. The material that is not conductive is offensive in nature, and the flow of current and the flow of energy via the dielectric substance is remarkably able to increase the dielectric voltage to 90o. This voltage is the immediate voltage that happens at the midpoint between the ground and phase components in the transformer. It is clear that no insulating material can be solely dielectric, it could have certain conducting characteristics. Additionally, it is important to be aware that the tan delta value of the transformer's insulating oil rises when there is a decrease in resistance of the oil and in reverse. Therefore, it isn't useful to conduct a resistivity test, and also a tan delta test for transformer insulation oil since they are interconnected and don't need separate testing. It is also possible to conclude that and is a sign of the conductivity of non-conductive, imperfect materials such as oil.
How do you test the dielectric strength of transformer oils Dielectric strength test for transformer oil?
Testing for oil involves measuring the breakdown voltage as well as the physical and chemical characteristics of the oil by using portable test equipment or in an in-house laboratory. A proper test can prolong the lifespan that the transformer will last, which decreases the requirement to purchase an upgrade.
Chemical properties of Transformer Oil
The analysis of moisture in transformer oil the presence of moisture subject, as well as water subject matter in transformer insulation oil, is a serious issue as it can adversely affect the dielectric properties present in the oil, which in turn could be responsible for the breakdown of the transformer. The insulation made of paper ( the cellulose papers) within the equipment could be similarly affected by the amount of water that is accumulating in the oil. The cellulose paper utilized as solid insulation used to protect the windings and core in the transformer absorbs liquid in the oil, and it loses its insulation properties in a substantial way and decreases the lifespan of the equipment. Paper can absorb moisture content since it is hygroscopic. When the transformer is fully loaded with loads, its temperature increases, and the content of wetness in the oil will be dissolved within it. This also leads to that water is released from paper. This makes it very difficult to collect a sample of the oil at a higher temperature. When oxygen from the atmosphere reacts with the transformer's oil acid compounds build up within it, which exceeds the saturation point of the water present in the oil. The acidic compounds that are formed start degrading the oil, which eventually causes the breakdown of the transformer. It is, therefore, better to determine the moisture in the oil and to take the necessary preventative measures to restore the integrity of the insulating oil.
It is the acidity that affects Transformer Oil - Transformer oil with acidic constituents can be dangerous for the efficient functioning of transformers that power the electrical system. Through the years of use the insulating oil, which serves as a dielectric material to protect the windings and the core of the transformer is dissolved by acidic compounds due to the different reactions it experiences. The acidic compounds that are formed during the working conditions of the equipment begin to degrade the insulation properties of both solid and liquid insulation materials. This is why it is important to test the oil to determine its acidity, and then get rid of the acidic components from the oil since it speeds up the process of aging by the process of oxidation. It is also possible to see rust in the components that the core is constructed occurs as well. The acidity is measured in terms of oil in one milligram of KOH must be counterbalanced by the acid components present in one gram of oil. This is known as neutralization.
Transformer Oil The physical characteristics of transformer oil
Flash Point The value of transformer Oil - The temperature of dielectric transformer oil when it begins giving out a vapor that creates an air-based mixture that is extremely explosive. The gas that is flammable is hazardous because it could cause sparks when exposed to flame. This flashpoint measurement is crucial as it determines the characteristics of the oil being exposed to the fire. It is therefore mandatory to have a transformer that is better-insulated oil that has a more powerful flashpoint.
Pour Point Valuation of Transformer Oil - The pour point value of the mineral oil that is insulating is the lowest point of temperature at which the oil started to flow, changing from a frozen state to a liquid. It is vital to constantly observe the point at which you pour transformer oil, especially if the device is operating in areas in which the temperature is typically lower than zero degrees. When the temperature falls rapidly, it is below the pour point the oil becomes frozen and begins cooling the components inside the machine. It is recommended to select oil for transformers with a high pour point. Its pour points are high. paraffin-based oil is higher in comparison to Naphtha-based transformer oil, however, it is recommended to make use of paraffin oil in areas with hot temperatures. The Pour Point for transformer oils is determined by the quantity of lubricant found within the oil. The Paraffin produced Transformer mineral oil is characterized by a greater pour point because it contains greater wax content.
Viscosity Index of the Insulating Transformer Oil - The viscosity of dielectric transformer oils is the measurement of the resistance the oil offers to ensure its continuous flow at temperatures that are normal for operating. The oil is a barrier to the flow of its fluid through the various parts of the transformer that increase the temperature. The most effective transformer oil has to maintain a low viscosity so that it creates an insignificant resistance to the flow that is normal and performs to perform the necessary functions, such as transferring the heat created by the transformer. It is also recommended that the viscosity of the transformer oil must be lower and should change slowly as the temperature of the oil drops. The majority of the transformer oil is more viscous once temperatures drop.
To learn more about the Properties of Chemical and Electrical properties of Transformer Oil keep following us.
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