Current sense transformers are typically designed to work with a one or two turn primary and a specific load resistance to obtain a fixed ratio of output voltage to primary current. While frequently designed with a toroidal core, current sense transformers can be configured in almost any form factor to suit your application. The accuracy of the current sense transformer depends mainly on the core material and the turns ratio.
Specifying a custom current sense transformer requires consideration of the following parameters:
- Input current range and frequency will determine how large the core needs to be. If the core is too small for the maximum primary current, it will saturate and result in measurement error or circuit damage. If it is too large, it may be more expensive and bulky for the application.
- Turns ratio helps determine resolution. The higher the turns ratio, the higher the resolution.
- The burden resistor and output voltage determine the ratio of output volts per amp of primary current.