What kinds of transformers are there?
Writer： Hengfeng you electric Time：2023-04-07 views：times
What is the classification of transformers?
The general classification of transformers can be summarized as follows:
1. Divided by phase number:
2) Three phase transformer: used for voltage rise and fall of three-phase system.
2. According to cooling mode:
1) Dry type transformer: relying on air convection for natural cooling or increased fan cooling, it is mostly used for power consumption of high-rise buildings, high-speed toll stations, local lighting, electronic circuits and other small capacity transformers.
2) Oil immersed transformer: relying on oil as cooling medium, such as oil immersed self cooling, oil immersed air cooling, oil immersed water cooling, forced oil circulation, etc.
3. By purpose:
1) Power transformer: used for voltage rise and fall of transmission and distribution system.
2) Instrument transformer: such as voltage transformer, current transformer, measuring instrument and relay protection device.
3) Test transformer: it can generate high voltage and conduct high voltage test on electrical equipment.
4. By winding form:
1) Double winding transformer: used to connect two voltage levels in the power system.
2) Three winding transformer: it is generally used in regional substations of power system to connect three voltage levels.
3) Autotransformer: used to connect power systems with different voltages. It can also be used as an ordinary step-up or step-down transformer.
5. According to the form of iron core:
1) Core transformer: used for high-voltage power transformer.
2) Amorphous alloy transformer: amorphous alloy iron core transformer is a new type of magnetic conductive material, and the no-load current decreases by about 80%. It is a distribution transformer with ideal energy-saving effect. It is especially suitable for rural power grid, developing areas and other places with low load rate.
3) Shell transformer: special transformer for high current, such as electric furnace transformer and welding transformer; Or power transformers for electronic instruments, televisions, radios, etc. Transformer is a device that transforms AC voltage, current and impedance. When AC current is connected in the primary coil, AC magnetic flux will be generated in the iron core (or magnetic core), causing voltage (or current) to be induced in the secondary coil. The transformer is composed of iron core (or magnetic core) and coil. The coil has two or more windings. The winding connected to the power supply is called the primary coil, and the other windings are called the secondary coil.
Classification by cooling mode: dry type (self cooling) transformer, oil immersed (self cooling) transformer and fluoride (evaporative cooling) transformer.
Classified by moisture-proof mode: open transformer, potted transformer and sealed transformer.
Classification by iron core or coil structure: core transformer (insert iron core, C-type iron core and ferrite iron core), shell transformer (insert iron core, C-type iron core and ferrite iron core), ring transformer and metal foil transformer.
According to the number of power phases: single-phase transformer, three-phase transformer and multi-phase transformer.
Classification of transformers
What are the classifications of transformers?
1. Classification by purpose: there are power transformers and special transformers (electric furnace transformer, rectifier transformer, power frequency test transformer, voltage regulator, mining transformer, audio transformer, medium frequency transformer, high frequency transformer, impulse transformer, instrument transformer, electronic transformer, reactor, transformer, etc.).
2. Classification by structure: there are double winding transformer, three winding transformer, multi winding transformer and autotransformer.
3. Classified by cooling mode: oil immersed transformer and dry-type transformer.
4. Classified by cooling mode: natural cooling type, air cooling type, water cooling type, forced oil circulation air (water) cooling mode, water internal cooling type, etc.
5. Classification by iron core or coil structure: core transformer (insert iron core, C-type iron core, ferrite iron core), shell transformer (insert iron core, C-type iron core, ferrite iron core), ring transformer, metal foil transformer, radial transformer, etc.
6. According to the number of power phases: single-phase transformer, three-phase transformer and multi-phase transformer.
7. Classified by conductive materials: copper wire transformer, aluminum wire transformer, semi copper and semi aluminum, superconducting and other transformers.
8. Classified by voltage regulation mode: it can be divided into non excitation voltage regulation transformer and on load voltage regulation transformer.
9. According to the insulation level of neutral point, there are fully insulated transformer and semi insulated (graded insulation) transformer.
Power transformer is one of the main equipment in power plant and substation. The function of transformer is multifaceted. It can not only raise the voltage and send the electric energy to the power consumption area, but also reduce the voltage to the use voltage at all levels to meet the needs of power consumption.
In short, the step-up and step-down must be completed by the transformer. In the process of transmitting electric energy in the power system, there will be two parts of loss: voltage and power. When transmitting the same power, the voltage loss is inversely proportional to the voltage, and the power loss is inversely proportional to the square of the voltage. The transformer is used to increase the voltage and reduce the power transmission loss.
The transformer is composed of two or more coil windings wound on the same iron core. The windings are connected through alternating magnetic field and work according to the principle of electromagnetic induction. The installation position of transformer shall be convenient for operation, maintenance and transportation, and a safe and reliable place shall be selected.
When using the transformer, the rated capacity of the transformer must be reasonably selected. When the transformer operates without load, it needs large reactive power. These reactive power shall be supplied by the power supply system.
If the capacity of the transformer is too large, it will not only increase the initial investment, but also make the transformer operate under no-load or light load for a long time, increase the proportion of no-load loss, reduce the power factor and increase the network loss. Such operation is neither economical nor reasonable.
The selection of transformer capacity is too small, which will overload the transformer for a long time and easily damage the equipment. Therefore, the rated capacity of the transformer should be selected according to the needs of the power load, and should not be too large or too small.
Reference source: Sogou Encyclopedia - transformer I, divided by phase
1. Single phase transformer: used for single-phase load and three-phase transformer group.
2. Three phase transformer: used for voltage rise and fall of three-phase system.
2、 By cooling mode
1. Dry type transformer: relying on air convection for natural cooling or increased fan cooling, it is mostly used for power consumption of high-rise buildings, high-speed toll stations, local lighting, electronic circuits and other small capacity transformers.
2. Oil immersed transformer: relying on oil as cooling medium, such as oil immersed self cooling, oil immersed air cooling, oil immersed water cooling, forced oil circulation, etc.
3、 By purpose
1. Power transformer: used for voltage rise and fall of transmission and distribution system.
2. Instrument transformer: such as voltage transformer, current transformer, measuring instrument and relay protection device.
3. Test transformer: it can generate high voltage and conduct high voltage test on electrical equipment.
4. Special transformers: such as electric furnace transformer, rectifier transformer, adjustment transformer, capacitive transformer, phase-shifting transformer, etc.
4、 Divided by winding form
1. Double winding transformer: used to connect two voltage levels in the power system.
2. Three winding transformer: it is generally used in regional substations of power system to connect three voltage levels.
3. Autotransformer: used to connect power systems with different voltages. It can also be used as an ordinary step-up or step-down transformer.
Transformer parameters
1. Rated capacity: refers to the rated output capacity of the transformer under rated working conditions (equal to U) × 1. Unit: kVA);
2. Rated voltage: the value of terminal voltage under no-load and rated tapping (i.e. primary and secondary side voltage);
3. No load loss: the loss of transformer under no-load condition (also known as iron loss);
4. No load current: the current value flowing through the primary coil under no-load condition;
5. Short circuit loss: the loss caused by the secondary short circuit when the primary side is connected with the rated current (mainly caused by the coil resistance);
6. Concept of tapping: in order to meet the needs of power grid operation, generally there are taps on the high-voltage side of the transformer, and the voltage value of these taps is expressed as a percentage of the rated voltage, that is, the so-called tapping voltage.
7. Active load: the load that generates machine energy or heat energy in the power system. However, the purely resistive load in the load only consumes active power, such as electric heating, electric furnace, lighting and other electric loads are completely active loads.
The loads of asynchronous motor and synchronous motor consume both active power and reactive power, and the part that works to produce machine energy belongs to active load. The active load shall be supplied by the active power of the generator.
8. Reactive load: the part that does not work in the power load. Reactive power is consumed only in inductive loads. Such as transformer, motor, air conditioner, refrigerator, etc. Therefore, while the generator outputs active power, it also needs to provide reactive power. When the reactive power cannot meet the power grid, the system voltage will drop.
In order to meet the needs of users, reactive power compensator should be installed in the substation to maintain the balance of reactive power, so as to maintain the voltage level.
9. Emergency reserve: one of the components of reserve capacity in power system. Because the power generation equipment may have temporary or permanent faults that affect the power supply, the system must set a certain number of emergency standby power supplies to ensure the safety of power facilities.
10. System disconnection: in order to prevent system out of step and accident expansion, it is a measure to decompose the complete power system into several independent systems that are no longer running synchronously. After splitting, some local systems may have insufficient power and the decrease of frequency and voltage. Therefore, it is necessary to cut off some loads to prevent the stability of the whole system from being damaged.
Reference source: Sogou Encyclopedia - transformers the classification of commonly used transformers can be summarized as follows:
1、 Divided by phase number:
1. Single phase transformer: used for single-phase load and three-phase transformer group.
2. Three phase transformer: used for voltage rise and fall of three-phase system.
2、 According to cooling mode:
1. Dry type transformer: relying on air convection for natural cooling or increased fan cooling, it is mostly used for power consumption of high-rise buildings, high-speed toll stations, local lighting, electronic circuits and other small capacity transformers.
2. Oil immersed transformer: relying on oil as cooling medium, such as oil immersed self cooling, oil immersed air cooling, oil immersed water cooling, forced oil circulation, etc.
3、 By purpose:
1. Power transformer: used for voltage rise and fall of transmission and distribution system.
2. Instrument transformer: such as voltage transformer, current transformer, measuring instrument and relay protection device.
3. Test transformer: it can generate high voltage and conduct high voltage test on electrical equipment.
4. Special transformers: such as electric furnace transformer, rectifier transformer, adjustment transformer, capacitive transformer, phase-shifting transformer, etc.
4、 According to winding form:
1. Double winding transformer: used to connect two voltage levels in the power system.
2. Three winding transformer: it is generally used in regional substations of power system to connect three voltage levels.
3. Autotransformer: used to connect power systems with different voltages. It can also be used as an ordinary step-up or step-down transformer.
5、 According to the form of iron core:
1. Core transformer: used for high-voltage power transformer.
2. Amorphous alloy transformer: amorphous alloy iron core transformer is a new magnetic conductive material, and the no-load current decreases by about 80%.
3. Shell transformer: special transformer for high current, such as electric furnace transformer and welding transformer; Or power transformers for electronic instruments, televisions, radios, etc.
Transformer is a device that uses the principle of electromagnetic induction to change AC voltage. The main components are primary coil, secondary coil and iron core (magnetic core).
The main functions are: voltage conversion, current conversion, impedance conversion, isolation, voltage stabilization (magnetic saturation transformer), etc. According to the purpose, it can be divided into: power transformer and special transformer (electric furnace transformer, rectifier transformer, power frequency test transformer, voltage regulator, mining transformer, audio transformer, medium frequency transformer, high frequency transformer, impulse transformer, instrument transformer, electronic transformer, reactor, mutual inductor, etc.).
Extended data:
1. Working frequency
The loss of transformer core is closely related to the frequency, so it should be designed and used according to the use frequency, which is called the working frequency.
2. Rated power
Under the specified frequency and voltage, the transformer can work for a long time without exceeding the output power of the specified temperature rise.
3. Rated voltage
It refers to the voltage allowed to be applied on the coil of the transformer, which shall not be greater than the specified value during operation.
4. Voltage ratio
It refers to the ratio of primary voltage and secondary voltage of transformer, which is different from no-load voltage ratio and load voltage ratio.
5. No load current
When the secondary of the transformer is open circuit, there is still a certain current in the primary, which is called no-load current. The no-load current is composed of magnetization current (generated magnetic flux) and iron loss current (caused by core loss). For 50Hz power transformer, the no-load current is basically equal to the magnetization current.
6. No load loss
Refers to the power loss measured in the primary when the secondary of the transformer is open circuit. The main loss is the core loss, followed by the loss of no-load current on the copper resistance of the primary coil (copper loss), which is very small.
Refers to the percentage of the ratio of secondary power P2 to primary power P1. Generally, the higher the rated power of the transformer, the higher the efficiency.
8. Insulation resistance
It indicates the insulation performance between coils of transformer and between coils and iron core. The insulation resistance is related to the performance, temperature and humidity of the insulating material used.
Reference source: Sogou Encyclopedia - transformer transformer is a device that converts AC voltage, current and impedance. When AC current is connected in the primary coil, AC magnetic flux will be generated in the iron core (or magnetic core), causing voltage (or current) to be induced in the secondary coil. The transformer is composed of iron core (or magnetic core) and coil. The coil has two or more windings. The winding connected to the power supply is called the primary coil, and the other windings are called the secondary coil.
Classification by cooling mode: dry type (self cooling) transformer, oil immersed (self cooling) transformer and fluoride (evaporative cooling) transformer.
Classified by moisture-proof mode: open transformer, potted transformer and sealed transformer.
Classification by iron core or coil structure: core transformer (insert iron core, C-type iron core and ferrite iron core), shell transformer (insert iron core, C-type iron core and ferrite iron core), ring transformer and metal foil transformer.
According to the number of power phases: single-phase transformer, three-phase transformer and multi-phase transformer.
Classification by purpose: power transformer, voltage regulating transformer, audio transformer, medium frequency transformer, high frequency transformer and pulse transformer.
2、 Characteristic parameters of power transformer
1 operating frequency
The loss of transformer core is closely related to the frequency, so it should be designed and used according to the use frequency, which is called the working frequency.
2 rated power
Under the specified frequency and voltage, the transformer can work for a long time without exceeding the output power of the specified temperature rise.
3 rated voltage
It refers to the voltage allowed to be applied on the coil of the transformer, which shall not be greater than the specified value during operation.
4 voltage ratio
It refers to the ratio of primary voltage and secondary voltage of transformer, which is different from no-load voltage ratio and load voltage ratio.
5 no load current
When the secondary of the transformer is open circuit, there is still a certain current in the primary, which is called no-load current. The no-load current is composed of magnetization current (generated magnetic flux) and iron loss current (caused by core loss). For 50Hz power transformer, the no-load current is basically equal to the magnetization current.
6 no load loss: refers to the power loss measured in the primary when the secondary of the transformer is open circuit. The main loss is the core loss, followed by the loss of no-load current on the copper resistance of the primary coil (copper loss), which is very small.
7 efficiency
Refers to the secondary power P2 and the primary power P1
