By appointment current transformers can be divided into metering, protective, intermediate (to include measuring devices in the circuit of relay protection, to align currents in the circuits of the differential protection, etc.) and laboratory (high precision, and many takzheso transformation coefficients). 2. By the nature of the current transformers installed distinguish: a) outdoor (open switchgear), b) for indoor use, and c) built-in electric vehicles and machines: circuit breakers, transformers, generators, etc., d) overhead – dressing on top of the bushing (for example, High input power transformer), and e) portable (to control measurements and laboratory tests). 3. By construction, the primary current transformers are divided into: a) multiturn (reel, with a loop winding and winding vosmerochnoy), b) single-turn (pivot), c) bus. 4. By way of installing current transformers for indoor and outdoor installation is divided into: a) pass b) support.
5. Implementation of isolation Current transformers can be divided into groups: a) with dry insulation (porcelain, bakelite, cast epoxy insulation, etc.), b) with paper-oil insulated with paper-oil capacitor insulation, and c) a filled compound. 6. According to the number stages of transformation of the current transformers are: a) single-stage, and b) two-stage (cascade). 7. According to the operating voltage transformers are distinguished: a) a rated voltage above 1000 V, and b) a rated voltage of 1000 V. A combination of different classification criteria introduced in the designation of the type current transformers, consisting of alphabetic and numeric parts. The current transformers are characterized by a rated current, voltage, class precision and design.