CT20–CT90 / CT20N / CT50 / CT60II / CT80II — 0.4 kV current transformers

Technical specifications

Specifications are taken from the manufacturer’s technical documentation. Updated 11/06/2026.

Description

The main CT20–CT90 range consists of busbar and cable transformers for a primary current up to 3200 A. Busbar types are slipped onto the switchboard bus, cable types are put over the cable, and in both cases the conductor itself serves as the primary winding. The CT80II in the split-core ABR version is rated for a current up to 1800 A; its core opens, so the transformer is mounted on a live line without disconnecting the cable or bus. The CT60II EXT is an outdoor version and is installed outside the switchgear room, at remote metering points. The 5 A secondary current of all models matches the standard input of meters, network analyzers and overcurrent protection relays. The transformers are made to the international IEC 60044-1 and the British BS 2627.

How to choose

First find out the line current and the mounting method. For a new switchboard with busbars or cable for a current up to 3200 A, the model is taken from the CT20–CT90 range to suit the conductor size, and for upgrading a live line the split-core CT80II ABR up to 1800 A is more convenient. If the transformer will stand outdoors, at a remote metering point, the CT60II EXT version is needed. The CT20N and CT50 models belong to the same range; the exact size is chosen by the window for the bus or cable and by the primary current.