hi all,
Can some one of you please name the sensors that I can use to measure 400 volts DC and also 230 volts AC using arduino due, 7amps AC-current.
please give the sensor IC number(if possible buy links) 
You will need two transformers for the AC - a current transformer (CT) and a small mains
transformer with low-voltage secondary that provides scaled version of the mains voltage.
For high voltage DC a carefully engineered resistive divider might be OK - it has to be
safe (which means multiple high-voltage rated resistors in the high-voltage arm, so
single-component failure cannot electrocute the user).
For DC current a hall-effect sensor like the ACS711/ACS712 would be appropriate
(at least one of those is 3.3V compatible.
To go with the transformers a suitable ADC is needed (one that has dual-rail analog
circuitry, or else single-supply and opamp to level-shift the ac signals).
Maybe checkout Home | OpenEnergyMonitor for AC mains design.
LEM specializes in this kind of equipment.