The function characteristics of micro transformer

The miniature transformer plays an important function and effect in the power supply system; its basic structure is composed of an iron core, a primary winding, a secondary winding, a terminal and an insulating support. The primary winding of the current transformer has fewer turns and is connected in series in the line to be tested, for the through-core current transformer; the line to be tested passes through the transformer, P1 enters, and P2 exits. the fewer turns. Combined with the effect and structure of the miniature transformer, the primary winding is connected in series in the circuit, and the number of turns is very small (one turn or several turns); therefore, the current size of the primary winding completely depends on the current size of the line under test. It has nothing to do with the magnitude of the secondary current. Under normal circumstances, the coil impedance of the AC ammeter or current relay connected to the secondary winding of the current transformer is very small, so the normal working state of the secondary circuit of the current transformer is close to the short-circuit state. According to the structural characteristics of the miniature transformer, it is worth noting that the secondary side of the current transformer in normal operation is never allowed to open circuit, because once the secondary side is open circuit, the impedance of the secondary circuit becomes infinite, and the secondary current is equal to zero ; Then the primary current completely becomes the excitation current, which generates extremely high voltage in the secondary winding, which directly endangers the safety of people and equipment on the secondary side. Therefore, it is not allowed to install a fuse on the secondary side of the current transformer, so as to avoid the fuse being blown and the secondary side becoming an open circuit. When using a miniature transformer, first of all, pay attention to ensure that its range meets the application requirements; once the current to be measured exceeds the range of the ammeter, it is necessary to replace the communication ammeter with a higher range and the matching current transformer. In addition, in actual use, it is also necessary to ensure that the iron core and secondary side of the miniature transformer must be firmly grounded to prevent the iron core from being accidentally electrified; once the primary side insulation is broken down, the secondary side will enter the high voltage, Directly threaten the personal safety of the secondary side and cause equipment damage.