transformer ground problem and attenuation network

Status
Not open for further replies.
G

gehan_s

Member level 3
Joined
Aug 31, 2012
Messages
62
Helped
3
Reputation
6
Reaction score
3
Trophy points
1,288
Location
Sri Lanka
Visit site
Activity points
1,799
Hi all,

I am designing a 3 phase power meter using the ade7758. To power the IC there is a transformer step down stage (See page 11 of a similar application note). There the neutral and the secondary of the transformers are shorted (both of them are named AGND). Can this be done ???? (In a way it is needed because the IC is sampling the AC voltage directly from the mains and it needs a reference point. But is it safe ??)

Secondly what is the point of having R20 to R36 for them are short circuited ???

Thanks in advance !!!!!!!!!!!!
 

Can't see this on this data sheet
Click to expand...
The AN641 link is pretty hidden in the post. Found it after reading the datasheet and the post a third time. :-(

Secondly what is the point of having R20 to R36 for them are short circuited ???
Click to expand...
The voltage divider calibration concept (shorted resistors) is explained in the application note. Don't need to retell it, I think.

But is it safe ?
Click to expand...
Energy meters have usually direct mains connection. Safe insulation is required. The external data interface has an opto coupler of sufficient voltage rating. During development, safety transformers or suitable differential probes are required.
 
Last edited:

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…