Designing a programme for power audit

I am designing a power audit program for industrial application in INDIA and the theme behind the exercise is explained as follows.

We need a energy meter to monitor the units consumed on online basis and for a large industrial application it may not be possible to buy many meters instead can we design an add-on card when attached to the ports of the motors with suitable interfaces display the units consumed on the laptop whether this laptop can take up the load or should we go in for a different configuration if so are they available in the market.

Thank you.

Kindly guide me.

NARAYANAN LAKSHMANAN INDIA