What kind of inductor/coil/transformer is this?

Thread Starter

Xavier Pacheco Paulino

Joined Oct 21, 2015
Found this device in a welder. I can only show that lateral view, since the other side is pretty tight to see. In the picture shown below, there are two red cables, and in the other side, two more red cables and two black cables. The side shown in the picture is connected to the collector of 4 IGBT in parallel. The side not shown (the red cables) are connected to the anode of 8 power diodes. I think I should draw a schematic for you to understand better. I might not be explaining well this power scenario. But what I really want to know is how that coil should work. How do the red cables in one side have to do with the red cables in the other side? I've seen some transformers and coils, but I'm not familiar with this one.



Joined Jan 17, 2007
Without a diagram it's definitely hard to tell. But my first guess is that it's probably a coil used for measuring current. That is, the coil is not physically connected to the welder's power supply, but rather to its controller. The red wire in the middle is probably just passing through its center, and the black cylinder on the left is probably a ferrite of sorts.


Joined Sep 30, 2009
The manufacturer and model number of the welder could also be helpful. Many of the companies have the schematics and repair manuals online. That may give a "name" to the device.