Sigma toroidal current transformer is used in combination with the leakage current protection LV circuit breaker, tripping coil and leakage current detection relay.
The rules to be considered when using the toroidal current transformer are;
All phases and neutral cables should be passed through the toroidal transformer.
The ground wire must not pass through the toroidal transformer.
The cables should be routed through the center of the toroidal transformer whenever possible.