I am trying to establish a suitable power supply for a device that I have that runs of 24VDC.
In the operating manual that I have for the device it says to ensure that a "grounded power supply" is used to prevent damage to both the device and the user. Also included in the manual was a schematic something similar to the following:
simulate this circuit – Schematic created using CircuitLab
The manufacturer of the device also sells a suitable but somewhat pricey power supply for the the device that looks like a normal power supply to me with a live, neutral and earth on the input.
All of this basically got me wondering about the internal anatomy of a bog standard power supply…
Does the power supply that the manufacturer sells for this device do something like this:
Or is this how all power supplies with L,N & E pins work?
As you may be able to tell, I am a little confused but hopefully you get the general jist of my problem.
If someone could shed some light, it would be very much appreciated. Thanks.
To clarify, this is the sort of thing that I am expecting to have to buy:
http://uk.rs-online.com/web/p/desktop-power-supply/0188781/
Best Answer
No, it is not the way all supplies work. In some cases, just the power supply case is grounded and the output may be floating or have an optional tie to ground (this is the way most bench supplies are wired, excluding some of the big SMPS types).
However, in this case we can see that the case is made of plastic and there is nothing to ground, so the output is most likely connected to the earth pin.
There is a third possibility- that earth pin of the supply is only connected to the output through a Y capacitor (for noise reduction purposes), but that is probably less likely.