What is it, Vex? What are you struggling while looking at the wiring diagram?
A customer asked me if FG needed to be wired, but when I was looking into it, PE came up and I couldn't distinguish... Can I review the difference between PE and FG again?
Vex! This is an important point for wiring, so make sure you remember it, okay? First of all, PE stands for Protective Earth.
Ah! We often hear the words "ground" and "grounding," but do they mean the same thing as PE?
Yes, basically it means the same thing. For example, when you install a washing machine, you must connect a ground wire, right?
I'm sure this is to prevent electric shock in case of electrical leakage.
Do you know why connecting a ground wire can prevent electric shock?
…。
This is because the ground wire has less resistance than the human body. Electrical current has characteristics to flow in the direction of lower resistance.
So if a ground wire is not connected, the human body could be exposed to a large amount of current in the event of an electrical leak.
Top: Without Ground Wire/Bottom: With Ground WireLocation of PE Terminal for Motor and Driver (One Example)
The same goes for a motor, which is very dangerous because if you don't connect a ground wire to the PE terminal, you could get an electric shock. By the way, when wiring, the key is to make it thick and short. It's more effective because the resistance is smaller and the current flows more easily.
I see... For safety reason, it is absolutely necessary to be connected.
That's right. Oriental Motor's AC input products are designed with Class I equipment construction, so they must have a ground wire. I think the explanation of "Electric Shock Protection Class" will be helpful.
I’ll read and study!
Although, some products, such as the EMU Series of low power consumption axial flow fans are AC input but designed with the structure of Class II equipment. Class II equipment doesn't require a ground wire. Since there is no need for crimping round terminals, wiring, or checking for continuity, the workload can be greatly reduced.
That’s a great benefit to the customer. But I don't often see Class I or II equipment, what do I need to look in order to confirm?
It's specified in the installation conditions in the operating manual. It's like this. Class II equipment is sometimes written as shown on the right.
I understand PE now! So what's FG?
In the first place, PE and FG have different purposes. FG stands for "frame ground," and it's mainly used to prevent malfunctions caused by noise.
In other words, the FG is connected to make the device work properly. I now understand that PE is for safety, and FG is to prevent malfunction, and they both need to be connected for these reasons!
Now you know the difference between PE and FG perfectly.
I've finally become a PE too~.
…? You will protect me from electrical leakage?
No, no, no, I mean [P] Perfect [E] Engineer.
...Answer to the customer before you say such a thing.
