some kind a coil???

Hi everybody, I'm taking apart a power supply and I came across a part I
that doesn't look familiar to me.. It consist of two coils one for each
wire. It's supplied with 220V alternating current and puts 220V alternating
current.... What can this be and what's it's function in my circuit board.
It's mounted between the power from the grid and a tranformer 220V --> 24V.

Greetz Geronimo ( [-})

 

Sounds like a common mode choke. They have two isolated coils on the
same, ungapped core. The line current passing in through one winding
and out through the other produce canceling magnetic fields, so the
core does not saturate from the load current. But if any common
voltage spike (same polarity on both lines) tries to get through, the
inductance is very high, as these signals produce adding magnetic
fields. This prevents much high frequency current entering (or
exiting) the supply from common mode, high frequency voltages.

 

Okay, I'm kind a new in electronics so I have got a lot to learn yet. I
tried to find the part in my books but couldn't find it. So the part is quit
common is it? Thanx for the explanation...

 

Quite. Getting the right mane is often most of the battle for
information.

Go to Digikey
http://www.digikey.com
and do a search for "common mode".