How Is My Power Supply Grounded?
There are generally two standard configurations when it comes to grounding in a switching power supply.
One method for a normal three wire line input is having the AC ground connected only to the inlet ground terminal. In this method, there is no connection to the output ground, or DC return, and is considered a “floating” AC ground.
The second method is to have the AC ground wired to the DC return. This connection has the added benefit of ensuring that the output ground is at the same potential as the input ground, so there is no possibility of any shock hazard.
For a linear supply using a laminated transformer, there are three common grounding methods:
- The AC ground can be connected both to the transformer core and output ground terminal, or the DC return.
- The AC ground can connect only to the transformer core.
- The AC ground can be carried through directly to a separate output ground lead.
The choice of grounding methods is often dictated by customer system requirements, and in some cases supply design topologies.