The connection of conventional CTs usually requires the interruption of the primary side circuit to pass cables or bus bars through the transformer core or to connect such cables to the primary terminals. The DP series transformers core may be easily opened and they may be installed and connected without any supply interruption, thus saving time and installation costs.
The main features of DP transformers are:
- Small size and easy mounting
- Wide inner window, allowing clamping of big cables or bus bars
- Wide range of sizes to accommodate all the existing installations
- High accuracy and reliability
Primary current: (see Table)
Secondary current: 5A, 1A
Standard approval: IEC44-1, BS7626
Maximum voltage: 0.72/3kV
Rated load: 1VA-30VA
Class: 0.5, 1.0, 3.0
Short-time thermal current: Ith=100 X In
Rated security coefficient: FS<5
Split Core CT Current Transformer:
DP split core CT transformers Split core current transformers have interleaved joint and hinge structure. Split core CTs have a removable section, so that they can be installed without interrupting the circuit.
A split core current transformer for coupling monitoring apparatus to a current carrying conductor includes a two-piece annular core structure formed by first and second arcuate core assemblies having windings, connectable to the monitoring apparatus, wound on laminated core sections, the laminated core sections each including a plurality of flat lamination elements arranged in a stacked configuration with alternate elements having generally circular end portions which project beyond the main body portion of the arcuate core section at each end thereof defining generally circular gaps….
Definition of Split-Core CT Current Transformers:
Just like the typical current transformer, the split-core current transformer measures alternating current flowing through a conductor.
The distinguishing feature of the split core current transformers is that their design permits them to be assembled around a buss bar without disconnecting the buss bar. The typical current transformer is usually a toroidal coil, which is slipped over the end of a buss bar, hence requires disconnecting the buss bar.
“C” – cores and “U” core structures are commonly used for split-core current transformers because they are relatively easy to take apart and put back together around the buss bar. Some sort of bracketry or band clamps and holds the assembled pieces of the split-core current transformer together. Historically, this has not been as practical (but is possible) for toroidal coils. The bracketry is more complicated. Typically, the coil’s must be sector wound on the toroid before cutting the core in half, whereas the “U” and “C” core structure of the typical split-core current transformer permit use of bobbin wound coils which can be wound independently of the core. There are now some flexible toroids, which permit the “split-core” feature of installing it around a buss bar.
Split-core current transformers for lower frequency applications (power frequencies) typically use grain oriented silicon steel or nickel alloys for the core material. There are some more exotic materials available. The material is cut into strips and then wound on an arbor (mandrel) to form a core. The core is then cut in half. These are known as “tape-wound” cores because their construction resembles a roll of tape.