1. Classification of electromagnetic voltage transformers
Voltage transformers can be divided into the following types:
According to the installation location, it can be divided into indoor and outdoor.
According to the number of phases, it can be divided into single-phase and three-phase.
According to the number of windings per phase, it can be divided into two windings and three windings.
According to the insulation, it can be divided into dry type, cast type, oil immersed type, cascade oil immersed type and capacitive type.
2. Structure type of electromagnetic voltage transformer
(1) Voltage transformers of 35kV and below
According to the different insulation methods, it can be divided into dry type, epoxy casting type and oil immersion type.
Dry voltage transformers are generally only used for low voltage indoor power distribution units.
Casting voltage transformers are used in 3 to 35kV indoor power distribution units.
Oil-immersed voltage transformers JDJJ2-35 and JDJ2-35 are widely used in 35kV systems.
(2) 110～220kV voltage transformer
110kV and above voltage transformers adopt cascade type, the iron core is not grounded, with potential, supported by insulation board.
The core of the JDX-110 voltage transformer is grounded and is a single-stage insulation structure.
The JCC type voltage transformer has a secondary winding for measurement and protection; a residual voltage winding, three-phase is connected to the open triangle, and the zero-sequence voltage is measured.
Both JDCF and JDX-110 voltage transformers are separated by two secondary windings, measuring and protection, and a residual voltage winding.