Current Transformer (CT) Calculator

Enter the rated primary (line) current. Sensible defaults are filled in for a 1000:1 current-sense CT with a 1-turn primary - change only what you need.

01

Primary current and ratio

Assumes a 1-turn primary - the line conductor or busbar passed once through the core.

Advanced settingsOptional - automatic values are suitable for beginners
02

Core and wire choice

Change any value after calculation to recalculate automatically.