CT principle of operation of transformer

According to the installation location, the split current transformer can be divided into indoor and outdoor. The indoor type is less than 20kV; the outdoor type is greater than 35kV and above.   According to the installation method, it can be divided into wall type, support type and load type. The wall-mounted type is installed in the hole of the wall or metal structure to save the wall bushing; the support type is installed on the plane or column; the load type is 35kV and above transformer bushing or multi-oil circuit breaker oil tank. It is called sleeve type.   Split current transformers can be divided into dry type, casting type, oil-immersed type, etc. according to insulation performance. Dry impregnated insulation glue is suitable for the opening and closing of low-voltage household current transformers; the casting type uses epoxy resin as the insulating material, which is mainly used for current transformers of 35kV and below; the oil-immersed type is mostly outdoor.   According to the coupling mode of high and low voltage components, the new split current transformer can be divided into electromagnetic wave coupling, capacitive coupling and photoelectric coupling. Among them, the optical current transformer has better performance. The new type of open-close current transformer is characterized by no direct electromagnetic connection between high and low voltage, which greatly simplifies the insulation structure; no need to consume a lot of energy during the measurement process; no saturation, wide measurement range, fast transient response, high accuracy; light weight and low cost.   In the same circuit, a large number of open-close current transformers are usually required. High-voltage current transformers are usually composed of multiple independent magnetic cores and secondary windings, without magnetic connection, and the primary winding is shared, forming multiple secondary windings with the same current ratio and current mutual inductance. Equipment For open-close current transformers of 110kV and above, the primary winding is usually divided into several groups, and the series and parallel connections of the windings are changed by switching to obtain a mutual inductance ratio of 2:3.