This toroid is designed for Vigilohm insulation fault locators and VigiPacT type A residual current protection and monitoring relays. It allows monitoring the fed component of Vigilohm Insulation Monitor and measuring a nominal current up to 250A for VigiPacT monitoring and protection relays. The transmission ratio is 1/1000. The inner diameter of the toroid is 120 millimeters and the weight is 0.450 kg. The cables must be centered inside the toroid and the diameter of all these cables should not exceed 60 mm. The maximum cross-section per phase (R, S, T, N) is 240mm² for a copper conductor.