Hello.

I´m still learning electricity and electronics (And English!) and there are some questions that I can´t solve looking on the internet.

If I connect the phase wire to ground the current find a way to move from the generator to earth, ok.

But if I have a 300v DC power supply, there will be a current flow (Electrons) if I connect the - to ground right? But what happens if I connect + to ground? Will there be a current flow of electrons from the earth to the power supply?

Tank you

Kind regards

 

Hello,there.Very good question!
If I just answer your question about the positive wire of a 300VDC power supply connected to earth ground it will make no sense to you.. therefore please forgive this long winded answer.
An earth ground is what most engineers would consider a true ground. An earth ground is when a circuit has a physical connection to the earth, in order to sink electrons through to a ground connected to the earth.
This ground is normally present on an electronic device that is powered by an AC plugged connected to an AC wall outlet. This type of ground is one in which the plug has 3 wires. With a 3-prong plug, one wire is positive, one is negative, and the other is the earth ground prong. This type of prong provides extra electrical protection. Because it has a direct connection with earth ground, it is only to sink electricity to the earth, giving less risk of a fire. Ground serves as a safety measure in circuits that are hooked up to earth ground. When a circuit is grounded directly to the earth, it is a safe line, because the earth is a huge reservoir that acts as a major sink for electrons. If a technician were to touch an earth ground, instead of the electrons sinking into the person, they would sink into the earth. When you make sure at least one side of your circuit is common to earth ground, it presents no shock hazard for a person touching ground. Ground is a neutral 0-volt line. The other type of ground is floating, or virtual, ground. This ground is not directly connected to the earth, and, thus, floating. Many battery circuits contain floating grounds and do not have to contain earth grounds because they carry a small amount of voltage. Thus, there's no real possibility of shock. However, for high-voltage applications, earth ground is essential, since the high voltage can be lethal to a person. This is why the circuit should be designed to sink directly into the earth

 

It does not matter if the power supply is AC or DC.
It does not matter which terminal you connect, positive or negative.
It does not matter if you connect or not connect to ground.

Think of it in this way.
For current to flow you need a circuit, i.e. a complete loop from the power supply and back to the power supply.
Once the loop is created, current will flow.
Firstly, establish where is the loop, with ground or without ground.
Do not worry about the direction of the current (or electrons). This will only confuse you.

 

Yes I meant an earth ground.

But I want to understand the direction of current.

So, If I connect the - to an earth grond there will be a flow of electrons to ground and if I conect the +to ground the electrons will flow from earth. Is that correct?

 

Yes I meant an earth ground.

But I want to understand the direction of current.

Current flows from a higher potential to a lower potential.

 

Ok, thanks

 

But if I have a 300v DC power supply, there will be a current flow (Electrons) if I connect the - to ground right? But what happens if I connect + to ground? Will there be a current flow of electrons from the earth to the power supply?

You shouldn't be working with lethal voltages until you have more knowledge.

Since you're still learning, you should use conventional current. That's more prevalent than electron current.

 

Sorry, I don´t speak english very well and maybe I didn´t explain very well.

When I am learning something, I need to really understand everything. The 300 DCV is only an example. I understand what is electric current, and how works in a simple circuit like a battery and a resistor, a coil or a capacitor. I also understand the importance of a well ground earth in a circuit wich involves dangerous voltages. But I want to understand the direcctions of the electrons when you connect DC to ground

That is all

 

But I want to understand the direcctions of the electrons when you connect DC to ground

Then you should use more realistic scenarios. Any novice working with 300VDC is likely going to get hurt or killed.

As I said, do yourself a favor and use conventional current instead of electron current. You'll be less confused in the end because conventional current is more commonly used.

 

Yes, I know I have use that. It just I am curious about what happend when you connect DC to ground

 

It just I am curious about what happend when you connect DC to ground

It depends on what you mean by ground and what components are in the circuit. If you want meaningful answers, you need to ask meaningful questions.

And, most will prefer a schematic over verbal descriptions of how things are connected. Even cartoons could be more intelligible than words.

EDIT: Here's a simple example:

Conventional current will flow from the positive terminal of the battery, through the resistor and LED, to the negative terminal on the battery. In this case, there is no "ground" point.

If you want to know how the electrons will flow, simply reverse the direction of conventional current. Electrons will leave the negative terminal of the battery and flow towards the positive terminal.

 

Yes, I know I have use that. It just I am curious about what happend when you connect DC to ground

Try it with something safe(r) like a 12v car battery.

 

Picture Earth floating in space. Earth (ground) is sitting at some potential voltage. But like a bird landing on a high voltage transmission line, they don't get a shock because there's no current flowing from their body to some other place. @MrChips said that "Current flows from a higher potential to a lower potential." And that's absolutely right. There has to be a pathway for current to flow. If you stick a wire in the ground and connect it to one end of a lightbulb and stick the other end in the air - the lightbulb will not light because there is no pathway. No circuit.

The word "Circuit" comes from the same word that means circle. In a circuit with a simple battery and a simple light, current flows from the battery, through the lightbulb and back to the battery. If the current can't complete its pathway then there is no current flow.

We refer to ground as a common point of reference. That reference can be quadrillions of volts. Connecting a wire to ground, to a lightbulb, a battery and back to ground - you've created a circuit. Regardless of what voltage the earth is sitting at - the lightbulb only sees the current from the battery, through the bulb, through ground and back to the battery.

In further keeping of what MrChips said, energy flows from the higher potential to the lower. Static electricity is a good example of that. You walk around the room, the carpet causes you to charge up with static electricity. Now you're walking around with 3,000 to 50,000 volts charge. You reach for the doorknob and get a heck of a shock. That's because the doorknob is at a lower potential. (or higher - it can be either way around). Because of the difference in charge you feel the sudden, and sometimes painful shock of the current as the two dissimilar charges equalize. That's not a circuit, that's the exchange of potential electrical voltage. Current is extremely low. Otherwise walking across the carpet and touching the doorknob would be lethal. It's not because the current is so low.

With your power supply, if it's grounded internally along with the negative output post, then (in theory) you can light the lightbulb from the positive post through the lightbulb and into ground. IN THEORY! Low voltage doesn't travel well through ground. And the further apart the two are the more resistance can be encountered, thus, limiting the amount of current so low that your lightbulb won't light. Concrete can be conductive. But it takes high voltage before it becomes dangerous. But to use concrete as a conductor at low power levels doesn't work because of the high resistance.

But lets stay simple and on topic:

what happens if I connect + to ground? Will there be a current flow of electrons from the earth to the power supply?

No. Not unless the power supply has its own internal ground. Then you have a short circuit and high amperage.

 

Perhaps a picture will suffice:

 

Perhaps a picture will suffice:
View attachment 209164

Short circuit is probably an extreme definition of the resistance of "The Ground".

 

Short circuit is probably an extreme definition of the resistance of "The Ground".

Yes. But in terms of understanding, it will suffice for a beginner.

 

Thank you everybody for your answers

...

Thank you very much, now I understand. Ok.

But if I connect the Phase of my home with the grounded earth, the current flow. Where is the close circuit there?

 

The pole transformer has a grounded line. If you connect a phase to ground at 120 or 240 VAC you create a circuit from the phase (line) to ground. From the ground back to the transformer. There will probably be a spectacular display of light.

 

Tony get the award for finally answering the question. Didn't anyone else notice that he talked about connecting only one terminal of the battery to ground?

Bob

 

Ahhhh, now I understand, I wass missing the conections of the transformer to ground. Thank you very much Tonyr1084

So this diagram is correct? I didn´t imagine that the soil conducts the electricity so well.

BobTPH, YESSSSSSSSS