The specification states that the 35KV substation is capable of obtaining the power supply after the main transformer is powered down. Therefore, in this case, the transformer used should be connected to the power supply side of the circuit breaker. My question is that the main transformer which, the main transformer is not connected to the power supply side of the circuit breaker?
1, the so-called main transformer or (plant) with transformers are transformers, but according to their use of different names.
The so-called main transformer: generally in the power plant or substation are so called, its function is for the system through the required level of power transformer; the so-called (factory) with the transformer is inside (power plant interior) Electrical equipment to provide power transformer.
2, the (plant) with the transformer power supply connected to the main transformer on the same bus, and some received another external power supply, so that when the main transformer can be maintained when the maintenance (plant) to continue to have power!
Selection of main transformers
Main transformer is mainly used for electrical system power supply, the general capacity of large, to ensure the reliability of electrical system power supply, improve the system impact resistance.
1, the number of the main transformer: In order to ensure the reliability of power supply, substation should be installed in general two main transformer.
2, the main transformer winding connection: 110KV using a direct grounding neutral point effective grounding system, using star wiring. If necessary, the use of triangular wiring by arc-suppression coil connected to the use of high-pressure side of the change. 35KV using arc suppression coil neutral point non-effective grounding system grounding point, the use of star wiring. 10KV generally use unattached system
3, the choice of the main transformer winding: China 110KV and above voltage transformer winding are used star wiring, 35KV also uses star wiring, 35KV following voltage transformer windings are triangular connection.
4, the choice of main transformer capacity: the main transformer capacity is generally based on substation built 5 to 10 years of planning load selection and take into account the late 10 to 20 years of load development, when a transformer outage, the remaining transformer capacity should Can guarantee 70% of the total load.
The choice of choice
Used to change the main power supply system, the capacity according to their own distribution load to choose.
The number of units used to consider the general standby power supply, when there are two used when the variable, the use of single bus segment wiring, usually run to limit the scope of failure to improve the reliability of power supply.
The power system uses 380 / 220V neutral point directly grounded three-phase four-wire system, power and lighting combined with a power supply.
Main Transformer:
Main transformer, referred to as the main transformer, English name: generator step-up transformer, referred to as GSU transformer or GSU.
The main transformer refers to a unit or substation of the total step-down transformer, its capacity is generally relatively large. Other transformers used as power distribution, commonly known as distribution transformers, the capacity is slightly smaller.
On the main transformer protection, as the main transformer, in general, relatively large capacity, requiring a higher reliability of the work. For different capacity of the transformer, the required installation of the protection category is not the same.
Transformers used:
In general, substation high voltage switchgear need to provide 220V power supply, DC screen also need 220 power supply continued float. As in the operation of high voltage cabinet, there is no low-voltage power supply, so in the high-voltage cabinet set a very small capacity of the transformer. Thus providing the first power supply required for the operation of the high voltage cabinet. When the transformer is put into operation, the low voltage cabinet has the second power supply of the low voltage power supply circuit, and then automatically switches to the normal low side power supply as the operating power source.
Features:
Thermal stability, high reliability, long service life.
Low loss, low noise, maintenance-free.
Small size, light weight, less space, low installation costs.
