Split Core Against Solid Core Current Transformers

The Magnetic Difference

A solid core is a continuous magnetic circuit. A split core has a mating face where the two halves meet, and that face is a small air gap however well it is machined. The gap raises the magnetising current, which is what costs accuracy at the same physical size.

The Installation Difference

A solid core has to be threaded onto the conductor, which means the primary circuit is broken during installation. A split core opens around a conductor already in place. On a plant that cannot stop, that difference outweighs everything else.

How To Decide

• Billing or revenue metering: solid core, Class 0.5S or 0.2S
• New build switchboard: solid core, chosen for cost and frame ladder
• Retrofit into a running installation: split core or clamp on
• Irregular bus, cable bundles or no clearance: flexible Rogowski coil
• Medium voltage retrofit: split core cast resin

Bodies Available In Each Family

Split core in this range covers square (DBP, DP/TP), clamp (HK, SCT, JW), ring (UK), outdoor waterproof (FSCT) and cast resin (LZCK/LMZK). Solid core covers the moulded case and busbar families (MES, CA, MBO, ABO, DSC, MR, RCT, MSQ, DX, DM).

One Thing People Forget

A split core has to be closed properly. A core left with a gap, or with dirt on the mating face, will read low and will hum. Clean the face, close it fully, and check the reading against a reference clamp before signing the point off.