We are fitting soft starters to some old motors (20 years old) - these motors have thermistors but they have never been used - hence we are unsure about the integrity of the insulation between the thermistor and the windings. The issue being, we are taking these old motors and likely increasing the thermal demands on them which may destroy the insulation and potentially put mains voltage on the thermistor and destroy the soft starter.
Also... there is a line in the EMX manual which states "The thermistor circuit must be electrically isolated from earth and all other power and control circuits"
So how does one do this? Is there galvanic isolation in the EMX3 thermistor input which accomplishes this function?
I understand that an external thermistor relay would accomplish this, but that would make the EMX3 thermistor input redundant