How Does This Power Supply Work?

[aperri]

Just got my new bench power supply from Circuit Specialists and I guess I am missing something here. It's a pretty basic power supply nothing fancy but I don't understand how the output terminals work. For instance I set it up to output 5V and I put my multimeter positive lead on the red terminal and the multimeter Negative lead on the green GRN terminal and read zero volts. I think thats odd. So I put the multimeter Negative lead on the black negative terminal and reads the +5V.

So my question is why don't I get a +5V reading across the supply RED Pos and GREEN Grn terminals with my multimeter?

Link to the power supply: CSI3005X5

Thanks Antney

AP

 

[I²R]

Because there's no electrical connection between the chassis ground (the green terminal) and the PS output. That is, the output is isolated from the mains. The ground terminal on the front of your PS is a convenient connection point to Earth ground for circuits which require it, but since the output isn't ground-referenced you don't measure any voltage between it and the output terminals.

 

[Boncuk]

power supply

The green (yellow) terminal indicates protective earth. You can check that by looking at the plug which goes from the power supply to mains. If that plug just has two connections (pins) the yellow terminal is a fake.

If the plug has three connections check if one of them (neither L nor N) is connected to the green terminal.

If it turns out OK you might strap your working place to earth. It's safer when soldering ICs directly onto the PCB. (static discharge)

 

[aperri]

Thanks that helps a lot.

 

[Bob Scott]

Aperri,

It is set up that way so that you can connect the ground yourself if you wish. If you wire the red terminal to the green, you will have a negative voltage with respect to ground on the black terminal if that is what you need.

 

[yngndrw]

It also means that you can connect two power supplies together in series.

 

[Hero999]

The green (yellow) terminal indicates protective earth. You can check that by looking at the plug which goes from the power supply to mains. If that plug just has two connections (pins) the yellow terminal is a fake.

If the plug has three connections check if one of them (neither L nor N) is connected to the green terminal.

If it turns out OK you might strap your working place to earth. It's safer when soldering ICs directly onto the PCB. (static discharge)

I don't know about where you live but all appliances with metal cases that don't have double insulation from the mains have to have an earth conductor fitted.

I would suspect that this is the case with this lab power supply, it has a metal case that is connected to earth.

Becareful, when running circuits that can gernerate high voltages from your power supply. The insulation from the DC output to earth is probably only rated for 250V to 500V at most. This means that if you run a flyback transformer circuit that produces 20kV and the output gets shorted to earth, the DC rail will float at 20kV which will totally ruin your power supply. To stop this from happening, always connect one of the power supply rails to earth whilst using it with circuits that generate high voltages.

 

[killivolt]

Aperri,

It is set up that way so that you can connect the ground yourself if you wish..

This means that if you run a flyback transformer circuit that produces 20kV and the output gets shorted to earth, the DC rail will float at 20kV which will totally ruin your power supply. To stop this from happening, always connect one of the power supply rails to earth whilst using it with circuits that generate high voltages.

If (that) and (this were ) then what ?

 

[Bob Scott]

This means that if you run a flyback transformer circuit that produces 20kV and the output gets shorted to earth, the DC rail will float at 20kV which will totally ruin your power supply. To stop this from happening, always connect one of the power supply rails to earth whilst using it with circuits that generate high voltages.

If (that) and (this were ) then what ?

Nonsense, every post you have made is flippant nonsense.

 

[killivolt]

Nonsense, every post you have made is flippant nonsense.

I really don't know if he would get shocked or not ? Just say yes or no. If I piss you off I really don't mean too !

 

[Hero999]

We're not talking about electric shock but the possibility of damaging the power supply by connecting a load that generates a high voltage to it.

 

[killivolt]

Ok, so he will still remain Isolated.

Thank you

Sorry Bob