Earth to neutral voltage detection circuit

Dear all.

I am looking for simple circuit that can detect earth to leakage fault. earth to neautral should be 0-5V , if voltage exceeds 5v the relay should turned on by microcontroller . can someone suggest me best and safety circuit .

I am planning to use Arduino as microcontroller.

Hi,

To find a suitable solution you should give more informations:
* do you need just a raw estimation of the voltage, or exact calculation (with true RMS for example)
* where do you want to set the threshold, and what tolerance do you accept?
* do you need to take care about DC voltages, too? (= switch relay when there is a DC offset of 5V)
* how fast do you need to react?
* is it possible to connect arduino_gnd with earth_gnd?..or do you need a fully isolated measurement method?

Consider to use some voltage_hysteresis or some delayed ON or OFF of the relay to avoid chattering.

Are you familiar with processing AC input to your ADC with interrupt driven fixed sampling rate? ..or do you rather like to get DC_style input voltages?

Klaus