1. Classification and models of power transformers
2. 1. Classification by use
3. (1) Step-up transformer: used by the power plant to transmit electricity to the outside.
4. (2) Step-down transformer: The substation of the power supply bureau is used for voltage conversion.
5. (3) Distribution transformer: used to supply power to users.
6. (4) Plant transformer: Provides internal electricity for the power plant.
7. (5) Transformer for station: Provide internal electricity for the substation.
8. (6) Converter transformer: for DC power transmission, one side is connected to AC power, and one side is connected to the converter valve.
9. (7) Rectifier transformer: used in thermal power plants to supply power to electrostatic precipitators.

01 Inrush current
When a transformer is first energized, a phenomenon called magnetizing inrush occurs. Although inrush currents are generally not as disruptive as fault currents, the duration of magnetizing inrush currents is on the order of seconds (compared to periods with fault currents).

Introduction
transformer
A device that changes voltage, current, or phase by coupling a magnetic circuit
Why learn Transformers?
Transformers are also known as stationary AC motors

This video showed you what a main power transformer look like.

The transformer is a static device in continuous operation, which is relatively reliable in operation and has less chance of failure. However, since most of the transformers are installed outdoors, and are affected by the load during operation and the short-circuit fault of the power system, various faults and abnormal situations inevitably occur during operation.

The grounding transformer is referred to as grounding transformer for short. According to the filling medium, the grounding transformer can be divided into oil type and dry type; According to the number of phases, the grounding transformer can be divided into three-phase grounding transformer and single-phase grounding transformer. The function of the grounding transformer is to provide an artificial neutral point for the system with ungrounded neutral point, which is convenient for the use of arc suppression coil or small resistance grounding mode, so as to reduce the capacitance current to ground in case of grounding short circuit fault in the distribution network and improve the power supply reliability of the distribution system.

Analysis of abnormal operation of transformers
Transformer sound is abnormal


As soon as the transformer is connected to the power supply, there will be a buzzing sound, which is mainly due to the effect of high-voltage magnetic flux. During normal operation, the sound of the transformer is uniform. When there are other noises, you should carefully find the cause and deal with it.

1. Analysis of abnormal operation of transformers
(1) The sound of the transformer is abnormal
As soon as the transformer is connected to the power supply, there will be a buzzing sound, which is mainly due to the effect of high-voltage magnetic flux. During normal operation, the sound of the transformer is uniform. When there are other noises, you should carefully find the cause and deal with it.

The parallel operation of transformers means that the primary windings of two or more transformers are connected in parallel on the busbar of the same voltage, and the secondary windings are connected in parallel on the busbar of another voltage.






Its meaning is: when one transformer fails, other transformers running in parallel can still continue to operate to ensure the power consumption of important users; or when the transformer needs to be repaired, the standby transformer can be connected in parallel, and then the transformer to be repaired is powered off and repaired. , which can not only ensure the planned maintenance of the transformer, but also ensure that the power supply is not interrupted and improve the reliability of the power supply.

Gas protection is the main protection for transformer internal faults. It can act sensitively to transformer inter-turn and inter-layer short circuits, iron core faults, internal bushing faults, internal winding disconnection, insulation deterioration and oil level drop. When a fault occurs inside the oil-immersed transformer, the arc will decompose the insulating material and generate a large amount of gas, which flows from the oil tank to the oil pillow, and its intensity varies with the severity of the fault, reflecting the air flow and oil flow The action protection is called gas protection, also called gas protection. During the operation of the transformer, due to internal faults, sometimes we cannot identify and take measures in time, which is easy to cause some accidents. After the protection of the gas relay, the occurrence of similar incidents can be avoided to a certain extent.

1. What is a transformer?


In the AC circuit, the device that increases or decreases the voltage is called a transformer. The transformer can convert any value of voltage into the voltage value we need with the same frequency to meet the requirements of electric energy transmission, distribution and use.


For example, the electricity from a power plant has a low voltage level, and the voltage must be increased before it can be transported to a distant power consumption area. The power consumption area must be reduced to a suitable voltage level to supply power equipment and daily electricity. Equipment.

Question:
"There is an old-fashioned transformer of 1000KVA with an existing load of about 200KW. If a new load of about 600KW is to be added, can this transformer withstand it?"