1. Why should the iron core of the transformer be grounded?
Transformer core grounding is for safety and electromagnetic compatibility considerations.
On the one hand, grounding the transformer core prevents contact voltages caused by ground faults, which can pose a shock hazard to humans. Because when a ground fault occurs on one side of the transformer, the iron core on the other side may have a voltage in contact with the earth. If it is not grounded, this voltage cannot be released.
On the other hand, grounding the transformer core can also reduce electromagnetic radiation interference, especially for radio equipment and communication systems. This is because the current will generate a magnetic field in the iron core. If the iron core is not grounded, this magnetic field may leak into the surrounding environment and interfere with the normal operation of other equipment.
In conclusion, grounding the transformer core is a protective measure against shock hazards and electromagnetic interference.
2. Why do transformers use silicon steel sheets as iron cores?
Transformers use silicon steel sheets as iron cores because silicon steel sheets have high magnetic permeability and low resistance.
In a transformer, the iron core mainly undertakes the role of conducting magnetic flux. Therefore, the magnetic permeability of the iron core is very critical. Silicon steel sheet is a specially treated steel with very high magnetic permeability, can effectively conduct magnetic flux, and can reduce the loss of magnetic flux and eddy current loss.
In addition, the transformer will produce electromagnetic induction phenomenon during the working process, which will generate eddy current in the iron core. These eddy currents cause loss of energy and heating of the core, reducing the efficiency of the transformer. The silicon steel sheet has low resistance characteristics, which can reduce eddy current loss and improve the efficiency of the transformer.
Therefore, using silicon steel sheet as the material of the transformer core can improve the efficiency of the transformer, reduce energy loss, and reduce heat generation of the transformer, thereby prolonging the service life of the transformer.
3. What is the protection scope of gas protection?
In oil-immersed transformers, the scope of gas protection inside the transformer mainly includes the gas content in the transformer oil.
Normally, the oil in an oil-immersed transformer is used for insulation and cooling, but when the transformer fails or ages inside, gases such as gas and hydrogen will be generated, which will lead to an increase in the gas content in the oil. If the gas content in the oil is too high, it will cause the insulation performance of the oil to decrease, which will cause the transformer to malfunction or even explode.
Therefore, in order to protect the safe operation of the transformer, it is necessary to monitor and control the gas content in the transformer oil. Generally speaking, the gas relay is a commonly used gas monitoring device in oil. The gas relay can monitor the change of the gas content in the oil, and send out an alarm signal when the gas concentration exceeds a certain threshold, so as to carry out repair and maintenance in time.
In short, the gas protection range inside the transformer mainly refers to the gas content in the transformer oil, which needs to be monitored and controlled by devices such as gas relays to protect the safe operation of the transformer.
4. How to deal with the failure of the main transformer cooler?
The failure of the main transformer cooler may cause the temperature of the main transformer to rise, thereby affecting the normal operation of the transformer. Therefore, if it is found that the main transformer cooler is faulty, it is necessary to take timely measures to deal with it. Here are some possible approaches:
Replacing Faulty Cooler Parts: If some parts in your cooler are damaged or malfunctioning, consider replacing those parts to restore the cooler to working properly. The specific operation needs to be carried out according to the structure of the cooler and the cause of the failure.
Clean the cooler: If the pipes or cooling fins in the cooler are clogged or dirt accumulates, it may reduce the cooling effect and affect the normal operation of the transformer. The way of cleaning can be used to remove the dirt and sundries inside the cooler to restore the normal operation of the cooler.
Strengthen monitoring and maintenance: In order to avoid the adverse impact of the failure of the main transformer cooler on the transformer, the monitoring and maintenance of the cooler can be strengthened. Regularly inspect and maintain the cooler, and find and solve problems in time, which can improve the reliability and stability of the cooler.
Temporary emergency measures: During the troubleshooting period, some temporary emergency measures can be taken, such as reducing the load of the main transformer, increasing ventilation, etc., to reduce the temperature of the transformer and ensure the safe operation of the transformer.
In short, for the failure of the main transformer cooler, it is necessary to take timely measures to deal with it to ensure the normal operation and safety of the transformer. The specific treatment method needs to be selected according to the structure of the cooler and the cause of the failure.
5. What are the consequences of parallel operation of transformers that do not meet the parallel operation conditions?
Parallel operation of transformers that do not meet the parallel operation conditions may lead to the following consequences:
Voltage instability: Different transformers may have different electrical parameters, such as transformation ratio, resistance, inductance, etc. If these transformers with different parameters are forced to run in parallel, the overall electrical parameters after paralleling may be unstable, thereby affecting the quality of power supply.
Uneven load distribution: If the transformers with uneven load distribution are forced to run in parallel, different transformers may bear different loads, thus affecting the service life and stability of the transformers.
Excessive temperature rise: If different transformers are operated in parallel, their heat dissipation conditions and methods may be different, which may cause excessive temperature rise of some transformers, and may even damage the transformer.
Safety accidents: If different transformers are operated in parallel, there may be differences in their connection methods and protection measures, which may lead to electrical failures or safety accidents.
Therefore, in order to ensure the normal operation and safety of transformers, it is necessary to select appropriate transformers for parallel operation according to the actual situation, strictly abide by the relevant parallel operation conditions and requirements, and ensure that the transformers match each other, complement each other, and work together to improve the quality of power supply. and stability.
7. What causes the transformer to make abnormal noise?
There can be a number of reasons why a transformer may be making unusual noises, here are some possible causes:
Short circuit or poor contact of the winding inside the transformer: Short circuit or poor contact of the winding inside the transformer may lead to unstable current or excessive current, resulting in abnormal sound.
Impurities or gases in the oil: Impurities or gases in the oil inside the transformer may cause unstable oil flow or air oscillations, resulting in abnormal noise.
Mechanical failure: Mechanical failures inside the transformer, such as equipment failures such as transformer cooling fans or pumps, may cause abnormal sounds.
Loose or leaky pipes: Loose or leaky pipes inside the transformer can cause air oscillations or unstable gas flow, which can produce unusual noises.
External environmental factors: Factors such as excessive temperature of the transformer operating environment or noise interference may also cause abnormal sounds.
Therefore, if the transformer makes abnormal noise, it is necessary to check and repair the transformer in time. The specific maintenance method needs to be selected according to the cause of the abnormal sound and the specific situation in order to restore the normal operation and stability of the transformer. At the same time, during the installation, operation and maintenance of the transformer, attention should be paid to environmental temperature, humidity, noise and other factors to avoid adverse effects on the transformer.
8. When is it not allowed to adjust the tap changer of the transformer on-load voltage regulating device?
The on-load voltage regulating device is a common accessory equipment of the transformer, which is used to adjust the transformation ratio when the transformer is running, so as to achieve the purpose of adjusting the output voltage. When using the on-load pressure regulator, the following points need to be paid attention to:
It is not allowed to operate under live conditions: because the transformer is working under live conditions, the tap changer of the on-load voltage regulating device will have an arc when it is adjusted, so it is not allowed to operate the tap changer under live conditions.
Frequent adjustments are not allowed: frequent adjustments to the tap changer of the on-load tap changer may cause damage to the tap changer or poor contact, thereby affecting the normal operation of the transformer.
Adjustment under heavy load or short circuit conditions is not allowed: Under heavy load or short circuit conditions on the transformer, tap changer adjustment may cause arcing or excessive current, resulting in damage to the tap changer or transformer.
Obey the operating procedures and safety measures: When operating the on-load pressure regulating device, you need to abide by the operating procedures and safety measures, such as wearing protective equipment and following the operating procedures to ensure safe operation.
In summary, it is not allowed to operate under live conditions, frequent adjustments, heavy loads or adjustments under short-circuit conditions. When operating the on-load pressure regulating device, the operating procedures and safety measures should be followed to ensure safe and stable operation.
9. What does the rated value on the nameplate of the transformer mean?
The rated value on the transformer nameplate refers to some important electrical parameters and performance indicators of the transformer. Usually includes the following aspects:
Rated capacity: The rated capacity of a transformer refers to the maximum load electric power that the transformer can continuously supply. For example, a 10MVA transformer means that the transformer's maximum load can reach 10 megawatts.
Rated voltage: The rated voltage of the transformer refers to the design voltage of the transformer. For example, a 220kV/110kV transformer means that the input voltage of the transformer is 220 kV and the output voltage is 110 kV.
Rated frequency: The rated frequency of a transformer refers to the power frequency for which the transformer is designed. In China, the power frequency is usually 50Hz.
Short-time withstand current: The short-time withstand current of a transformer refers to the maximum current value that the transformer can withstand in a short period of time. For example, the short-term withstand current of a transformer is 50kA, which means that the transformer can withstand an instantaneous current of up to 50 kA.
Insulation level: The insulation level of a transformer refers to the insulation performance of the transformer at the time of design. For example, a 220kV transformer means that the designed insulation voltage of the transformer is 220 kV.
Cooling method: The cooling method of the transformer refers to the heat dissipation method of the transformer. For example, transformers can dissipate heat through natural cooling, forced air cooling, or forced water cooling.
To sum up, the rated value on the transformer nameplate refers to some important electrical parameters and performance indicators of the transformer, which is of great significance for the selection, installation and operation of the transformer.
10. Why does the current source inverter need a larger transformer capacity?
Current source inverter is a common type of inverter. Its control method adopts current loop control, which has the advantages of high precision and strong adaptability, and is widely used in industrial production. Due to the working characteristics of the current source inverter, a large transformer capacity is required for the following reasons:
The current source inverter adopts the intermediate inductance: the current source inverter adopts the intermediate inductor, which can realize the phase difference between the output voltage and the current, so as to realize the frequency conversion control. However, since the intermediate inductor needs to withstand large current and voltage, it is necessary to select a transformer with a larger capacity to ensure the normal operation of the inductor.
Current source inverter has a higher power factor: The current source inverter has a higher power factor, which can achieve higher power factor correction, thereby reducing grid harmonic pollution. However, since a higher power factor requires larger capacitor support, a transformer with a larger capacity needs to be selected to meet the power supply requirements of the capacitor.
Current source inverter needs additional power supply: The circuit of current source inverter needs additional power supply to ensure the normal operation of the current loop control. These additional power sources need sufficient capacity to support, so a transformer with a larger capacity needs to be selected to meet the power supply requirements.
Therefore, the current source inverter needs a larger transformer capacity to ensure the normal operation of the intermediate inductor, support the power supply of the capacitor and meet the power supply requirements. When selecting a transformer, it needs to be selected according to the actual electrical parameters and performance requirements to ensure the normal operation and stability of the inverter.
11. What is the capacity of the transformer related to?
The capacity of the transformer refers to the maximum load electric power that the transformer can bear. The capacity of the transformer is related to the following factors:
Input voltage and output voltage: The input voltage and output voltage of the transformer determine the transformation ratio of the transformer, which affects the capacity of the transformer. The higher the input voltage of the transformer and the lower the output voltage, the larger the transformation ratio and the larger the capacity.
Load nature: Different loads have different power factors, harmonic content and other characteristics, which affect the capacity of the transformer. For inductive loads, the capacity of the transformer can be appropriately reduced; for nonlinear loads, the capacity of the transformer needs to be appropriately increased.
Rising temperature: The capacity of the transformer will decrease as the temperature rises. Therefore, it is necessary to consider the appropriate heat dissipation method and heat dissipation area when designing the transformer to ensure that the temperature rise of the transformer does not exceed the allowable range.
Connection method: Different transformer connection methods, such as star, delta, etc., will also affect the capacity of the transformer. For the star connection, the capacity of the transformer can be increased by about 3 times; for the delta connection, the capacity of the transformer is relatively small.
Insulation level: The insulation level of the transformer determines the insulation capability and safety performance of the transformer, and also affects the capacity of the transformer.
To sum up, the capacity of the transformer is related to factors such as input voltage and output voltage, load nature, temperature rise, connection method and insulation level. When selecting a transformer, it is necessary to comprehensively consider various factors according to the actual situation to ensure the normal operation and stability of the transformer.
12. How to improve transformer performance?
The efficiency of the transformer refers to the energy conversion efficiency of the transformer, that is, the ratio of the output power to the input power. Improving the performance of transformers can reduce energy loss and energy consumption, thereby improving the economy and reliability of transformers. Here are a few ways to improve transformer performance:
Optimizing transformer design: When designing a transformer, optimized design methods can be used, such as reducing the reluctance of the iron core and winding, reducing copper loss and iron loss, etc., thereby reducing the energy loss of the transformer and improving performance.
Choose high-quality materials: When manufacturing transformers, you can choose high-quality materials, such as low-loss silicon steel sheets, high-conductivity materials, etc., to reduce material loss and energy consumption and improve performance.
Adopt energy-saving measures: During the operation of the transformer, energy-saving measures can be adopted, such as adopting a high-efficiency cooling system, reducing the load rate of the transformer, optimizing the operation scheduling of the transformer, etc., to reduce energy loss and improve efficiency.
Regular maintenance and overhaul: Regular maintenance and overhaul of transformers can maintain the normal operation and stability of transformers, thereby reducing energy loss and improving performance.
Choose the appropriate transformer connection method: Different connection methods of the transformer will also affect the performance of the transformer. When choosing a transformer connection method, the optimal connection method can be selected according to actual needs and load characteristics to improve efficiency.
To sum up, improving transformer efficiency can be achieved by optimizing design, selecting high-quality materials, adopting energy-saving measures, regular maintenance and overhaul, and selecting appropriate connection methods. In practical applications, various factors need to be considered comprehensively to select the most suitable method for improving performance.
14. What is eddy current? What are the disadvantages of eddy current generation?
Eddy current refers to a kind of current generated in the conductor, which is the induced current caused by the change of the magnetic field. The eddy current forms a circular current flow path in the conductor, and this current forms a motion state similar to an eddy current inside the conductor, so it is called an eddy current.
The generation of eddy currents has the following disadvantages:
Energy loss: Eddy currents create circular currents in conductors, which generate heat as they flow continuously in conductors. Since the generation of eddy currents is caused by changes in the magnetic field, in equipment such as transformers and motors,
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