I have written up a blog about differential and isolation amplifiers for use with a current shunt at:
https://electronicsknowhowblog.wordpress.com/2015/03/13/cursns4-amplifiers-difference-isolation/

also at:
http://www.element14.com/community/...03/13/cursns4-amplifiers-difference-isolation

 

on the element14 blog someone made useful observations...

The problem with isolation amplifiers is the high cost, both of the amplifier itself and the isolated power supply required. The amp specs are often poor in some respects.

For high side current measurements it is a good idea to consider alternatives as well - like current sensors or hall effect sensors.

And for some applications a few extra resistors can massively increase the amplifier's common mode range (at the expense of noise and common mode rejection) - see amps like: AD8479 (600V, and pretty good general specs) or the older INA117 (200V). (£5.05 and £7.15 each (1 off Farnell) compared with £4.33 for the ACPLC790 which also needs an isolated power supply).

 

I have written up a blog about differential and isolation amplifiers for use with a current shunt at:
https://electronicsknowhowblog.wordpress.com/2015/03/13/cursns4-amplifiers-difference-isolation/

also at:
http://www.element14.com/community/...03/13/cursns4-amplifiers-difference-isolation

I've added the blog on allaboutcircuits at...

http://forum.allaboutcircuits.com/b...eed-an-amplifier-difference-or-isolation.693/

 

On another blog someone suggested a really good range of components for current shunt monitoring. These things are high side monitors and have a common mode capability between 20V and 60V.

http://diodes.com/catalog/current_output_79/

...Peter