An electrical interface , for connection to a Rogowski coil arranged around a primary conductor , including: an input configured to sample an input voltage signal (u s (n)) from the Rogowski coil ; and an integrator circuit including an integrator module configured to integrate the sampled input voltage signal (u s (n)) to provide an output voltage signal (u INT (n)) from which can be derived a primary current (i p (n)) flowing through the primary conductor , the integrator module employing a transfer function that includes an attenuation factor (A), wherein the integrator module is or includes one or more of: - a first rectangular integrator embodying a transfer function in the discrete time domain of the form H z = 1 1 − e − AT s N d z − N d ; - a second rectangular integrator embodying a transfer function in the discrete time domain of the form H z = 1 N d ∑ k = 0 N d z − k 1 − e − AT s N d z − N d ; - a trapezoidal integrator embodying a transfer function in the discrete time domain of the form H z = 1 N d ∑ k = 0 N d z − k − 1 2 − 1 2 z − N d 1 − e − AT s N d z − N d ; and - a Taylor's approximation integrator embodying a transfer function in the discrete time domain of the form H z = 1 6 1 + 4 z − N d / 2 + z − N d 1 − e − AT s N d z − N d , where, A is the attenuation factor; T s is a sampling period of the input voltage signal (u s (n)); and N d is a down-sampling scale. an input configured to sample an input voltage signal (u s (n)) from the Rogowski coil ; and an integrator circuit including an integrator module configured to integrate the sampled input voltage signal (u s (n)) to provide an output voltage signal (u INT (n)) from which can be derived a primary current (i p (n)) flowing through the primary conductor , the integrator module employing a transfer function that includes an attenuation factor (A), wherein the integrator module is or includes one or more of: - a first rectangular integrator embodying a transfer function in the discrete time domain of the form H z = 1 1 − e − AT s N d z − N d ; - a second rectangular integrator embodying a transfer function in the discrete time domain of the form H z = 1 N d ∑ k = 0 N d z − k 1 − e − AT s N d z − N d ; - a trapezoidal integrator embodying a transfer function in the discrete time domain of the form H z = 1 N d ∑ k = 0 N d z − k − 1 2 − 1 2 z − N d 1 − e − AT s N d z − N d ; and - a Taylor's approximation integrator embodying a transfer function in the discrete time domain of the form H z = 1 6 1 + 4 z − N d / 2 + z − N d 1 − e − AT s N d z − N d , where, A is the attenuation factor; T s is a sampling period of the input voltage signal (u s (n)); and N d is a down-sampling scale. - a first rectangular integrator embodying a transfer function in the discrete time domain of the form H z = 1 1 − e − AT s N d z − N d ; - a second rectangular integrator embodying a transfer function in the discrete time domain of the form H z = 1 N d ∑ k = 0 N d z − k 1 − e − AT s N d z − N d ; - a trapezoidal integrator embodying a transfer function in the discrete time domain of the form H z = 1 N d ∑ k = 0 N d z − k − 1 2 − 1 2 z − N d 1 − e − AT s N d z − N d ; and - a Taylor's approximation integrator embodying a transfer function in the discrete time domain of the form H z = 1 6 1 + 4 z − N d / 2 + z − N d 1 − e − AT s N d z − N d , where, A is the attenuation factor; T s is a sampling period of the input voltage signal (u s (n)); and N d is a down-sampling scale. A is the attenuation factor; T s is a sampling period of the input voltage signal (u s (n)); and N d is a down-sampling scale. <EOS>