Current transformers are classified by insulation medium

1. Dry type current transformer: It is made of ordinary insulation material and treated with immersion paint as insulation.
2. Casting type current transformer: A current transformer formed by casting epoxy resin or other resin mixed materials.
3. Oil immersed current transformer: It is usually outdoor type and is insulated with insulating paper and oil.
4. Gas insulated current transformer: The main insulation is composed of gas.