I need help with coding for induction motor protection using Atmel

The motor protector counts with one LCD, 4 potentiometers and I'm using a Arduino Pro Mini for prototyping with Arduino IDE. And also a MOSFET. I already a the code written by myself but came to a wall where I don't know how to overcome. The LCD shows which is the lowest voltage (undervoltage protection) and also the highest voltage (overvoltage protection) acording to 2 potentiometers. And also the voltage. I can't use delay() since it pauses the program. When I use delay() it won't get to do anything. I use the potentiometers to set a time for when it bypasses the one of the voltage potentiometers to wait 0.5 to 5 seconds before switching off the contactor/relay ( contactors usually use 100 V to 240V) driven by a MOSFET. The last Potetiometer (remember we have 4 of them, 2 voltage potentiometers and 2 timing potetiometers) is to set a time of 30 second to 5 minutes. This timing event is to keep the motor from turning on again right after its turned off, preventing possible damage. This product is going to be used with a induction motor that drives a pump in a water well. To measure the voltage from 3 Phase 480 Volts is a bit challenging. Since I want to keep it cheap but very useful. I was thinking of doing this with voltage dividers and with transistors to switch from phase to phase (First reading 2 wires for 0.5 - 1 second... That would mean 3 readings).