So I'm writing some host side software for Crompton Ci3 Power meter, and I thought to show the insides of it. The unit itself is a three channel industrial voltage, current and harmonics monitor. It is used in grid substations. Datasheet It is made out of one 4 sided PCB and LCD. Power tracks are in middle layers, probably for safety reasons.
On the left there are 0.015Ω shunt current sense resistors for current and wattage measurements. On the center is probably the power supply for the logic. On the right side there are precision voltage dividers (made from couple of megaohm resistors). Left bottom - LCD flex cable connector. Top right - crystal and decoupling capacitors for MCU.
This is much more boring, and for some weird reasond, covered with some goo. There are some passives in the current measurement section. Also there is the main MCU of the unit. It is Atmel's AtXMega256A3 with some firmware sticker on it. They problably chose this processor for its fast ADCs. On the right there are programming pads but the firmware is probably write protected. The board runs on 3.3V logic.
And finally - the RS485 plugin board. It has MAX1483 RS485 tranciver chip and three optocouplerers for protection. On the final version of the product I'm working on I will probably omit this board for cost savings, and mount my own board instead of the plugin board.