Power supply GND

I have bought a power supply with output 12V, 6A. It has 5 positions for cables: L, N, GND, -V, +V. My question is: the GND is common to both the AC input and DC output? So I connect the cable from the AC input and the cable for the DC output?

the GND is common to both the AC input and DC output?

That is going to depend on the design of the power supply. Can you please supply a link to what you have got ?

Yes, LRS-75-12, here: LRS-75-MEAN WELL Switching Power Supply Manufacturer

alex5678:
I have bought a power supply with output 12V, 6A. It has 5 positions for cables: L, N, GND, -V, +V. My question is: the GND is common to both the AC input and DC output? So I connect the cable from the AC input and the cable for the DC output?

Your Ohmmeter will quickly tell you what is connected to what.

If you live in North or South America, the "L" is connected to Line, or the black wire in your cord. The "N" is connected to the neutral or white wire, and the "GND" is connected to the green or ground wire in your cord.

In usual power supplies, the -V is internally connected to the power supply ground and the "GND" position. You can check this with your meter.

Some power supplies do not connect the -V to the power supply chassis. This is called an isolated power supply. It's up to you to decide if you need to connect the isolated -V to ground. All depends on what type of project you have in mind.

Paul

In the respect of using an Arduino You connect the V- to Arduino GND.

Paul_KD7HB:
Your Ohmmeter will quickly tell you what is connected to what.

If you live in North or South America, the “L” is connected to Line, or the black wire in your cord. The “N” is connected to the neutral or white wire, and the “GND” is connected to the green or ground wire in your cord.

In usual power supplies, the -V is internally connected to the power supply ground and the “GND” position. You can check this with your meter.

Some power supplies do not connect the -V to the power supply chassis. This is called an isolated power supply. It’s up to you to decide if you need to connect the isolated -V to ground. All depends on what type of project you have in mind.

Paul

I live in Europe, the AC (220 Volts/50Hz) has three cables: 1 brown, 1 light blue and 1 bicolor green/yellow

The green/yellow is the safety cable for the mains part of the supply. Never connect that to low voltage circuitry.
The other 2 mains cable are "don't care as Your outlet most likely don't tell what is neutral and what is line. It's not needed.

Paul_KD7HB:
In usual power supplies, the -V is internally connected to the power supply ground and the “GND” position.

This is only generally true for PC power supplies, including laptops. It is a major nuisance when working with audio as you get “hum loops” in the ground connections, so power supplies with a two-pin power plug are preferred as they must necessarily (except for un-certified “no-brand” ones from China) have proper double-insulation. Many interfaces - such as “RCA” connectors and traditional “phone” jacks - have their “ground” connected to the equipment case by default.

Paul_KD7HB:
Some power supplies do not connect the -V to the power supply chassis.

The general-purpose supplies such as the OP mentions will not have the negative connected to mains ground. This would severely limit their applications.

My question is: the GND is common to both the AC input and DC output?

  • On this supply, is earth ground, same as "G" on the high voltage AC side (Line/Neutral/Ground).
  • Use V- as your Arduino GND.
  • Do not jumper V- to as this will short out isolation from the AC input.

As I know from my laptop's power supply, they become hot. However this industrial power supply has many holes due to Faraday cage. Can I put a PCB/proto board above the power supply? Os is it risky?

As long as you give adequate clearance for ventilation - 2 cm would be a reasonable minimum spacing, given that there is no other enclosure within 10 cm or so.

Because there is no space in the project box, can I attach the pcb/proto board on the power supply's cage IF I use a small fan to cool it from the side of the cage?

Just adding a fan is not safe. Mounted, directed, the wrong way it can even make things worse.
If the project box is too small it only tells that preparations are not the best. Use a bigger box.