Introduction of transformer core
Transformer core, mainly responsible for the magnetic circuit in the circuit. At present, most transformer cores on the market are made of silicon chips, but a few are made of magnetic sheets (chips made of magnetic sheets are gradually being eliminated).
Transformer core action
The function of transformer core is mainly in two aspects: hysteresis loss and eddy current loss.
1, hysteresis loss, it refers to the situation that the transformer will produce iron loss due to hysteresis when working in AC state, and the use of transformer core can change this phenomenon to some extent. And can also reduce the elevation of the transformer surface during operation.
2. Eddy current loss refers to the alternating current generated by the transformer at work, which will change with the induced current generated by the magnetic flux in the iron core. This change is called eddy current. When the eddy current disappears, the surface temperature of the iron core will rise, but in this process, our resistivity will increase because of the material of the iron core (silicon), which can reduce the effect of eddy current.
Classification of transformer cores
Generally, it can be divided into the following four categories: shell and core cores, single-phase and three-phase cores, solid and planar cores, laminated cores and wound cores.
Transformer core composition
It is mainly composed of three parts, namely, main body, fastener and insulation.
Calculation of cross section of transformer core
The power of transformer is calculated according to the cross-sectional area of core central column, the size of core window, input voltage and output voltage. Firstly, the number of turns is calculated according to the cross-sectional area of the iron core and the input voltage. Then calculate the wire diameter (wire diameter of enameled wire) according to the window size and the number of turns, and then calculate how much current can pass according to the wire diameter. To calculate his strength. According to the formula:
Turn left | turn right N=4.4fbs/ 104, where N= turns, f is frequency, b is magnetic flux density of silicon steel sheet, generally taking 10000 gauss as standard, and s is voltage. The number of turns is calculated step by step.
Power calculation of transformer core
P (w) = s (mm) 2 =19 *19 = 361W. A single-phase 220V transformer with a capacity of 300VA can be manufactured. It is known that the cross section of the money core is 19mm2, and the silicon steel sheet with silicon content of 9000 gauss is used to select the ampere ratio. 45/ 19=2.37 takes 3 turns per volt, 3*220=660 turns for primary winding and 3* 12=36 turns for secondary winding. Select the cross-sectional area of the primary line, the current is 300VA/220= 1.36A, and the safe passing current per square millimeter is 5A = 1.36/5=0.28 square millimeter. You can choose an enameled wire with a wire diameter of 0.6 mm. The cross-sectional area of the secondary line is 300/ 12 = 25A, and 25/5 = 5mm. Enamelled wire with a wire diameter of 2.6mm can be selected. If there is a surplus in the core, the diameter of the main and secondary lines can be thicker.
Transformer core grounding
When the transformer is in use, the iron core and the parts around the iron core are in a strong electromagnetic field. Therefore, due to the influence of electric field, the iron core itself will have a high potential to the ground. If there is no wire connection between the iron core and the ground, there will be a potential difference between the iron core and the ground and an intermittent discharge will occur. And there will be a strong electromagnetic field near the winding, which makes the iron core and parts in unequal magnetic fields, and there is a potential difference between them. Perhaps the potential difference is not very large, but it is enough to make it break through a small insulation gap, thus leading to continuous discharge. This is absolutely not allowed in power management, and it is difficult to find out if you want to stop this phenomenon, because some small insulation gaps are invisible to our naked eyes. So be sure to connect the iron core with the ground.
How to connect transformer core to ground?
Iron core grounding is usually point grounding, and there is no electricity between the steel sheets in the iron core, so for the sake of safety, never ground all the steel sheets. When the iron core is grounded, we only need to ground one of the steel plates, not all of them, because although there is no electricity between the steel plates, if all the steel plates are grounded, the ground will become a conductor, so that the steel plates can conduct electricity, thus disturbing the eddy current. Therefore, one-point grounding can not only make the current flow to the earth, but also not disturb the eddy current, thus achieving the purpose of grounding the iron core.
Transformer core manufacturer
Guangdong Haihong Transformer Co., Ltd. specializes in producing three-dimensional wound core transformer cores, which is the largest three-dimensional wound core manufacturer in China at present. The single-phase winding core distribution transformer produced by our company is a single-phase three-wire product, which has passed all type tests and other tests. The low voltage combination of this transformer is 2×0.23kV, which is different from the common single-phase double-wire transformer in principle and application. The low-voltage current of this transformer is only half of the rated current of ordinary single-phase transformer (the voltage of a 1-a2 is twice that of 230V, so the current is only half), which brings the greatest benefit that the line loss of the former is only 1/4 of the latter, which is the main reason why most foreign countries use this single-phase transformer. This product complies with national standards GB 1094 Power Transformer, GB/T645 1 Technical Parameters and Requirements of Three-phase Oil-immersed Power Transformer and JB/ 103 17-02 Technical Parameters and Requirements of Single-phase Oil-immersed Distribution Transformer.
Shandong Liaocheng Transformer Co., Ltd. is quite good. Is a manufacturing enterprise that mainly produces complete sets of low-voltage power equipment such as power transformers, dry-type transformers, American box transformers and European box transformers. The company is located in Liaocheng City, Shandong Province, where China is a famous historical and cultural city, Jiangbei Watertown and Liaocheng University are located. It is 90 kilometers away from Jinan, the provincial capital, and there are expressways and railways connected. Beijing-Kowloon Railway and Han Ji Railway meet here, and the traffic is very convenient.