impedance

[John-tyler]

I have been reading up on testing circuits as i was reading about the loop impedance test it said (the purpose of this test is to determine the impedance of the earth fault return path) could any one tell me what impedance means in a non technical way as iam not the sharpest tool

 

[davy_owen_88]

Impedance = opposition to the flow of current,

When you are measuring the earth fault loop impedance you want there to be as little opposition as possible, so a very high current can flow and therefore activate the overcurrent device very quickly.

 

[bernardgreen]

Impedance is the measure of how much difficulty the electrons have getting along the wire. Higher the impedance the more difficult it is for an electric current to flow.

There is a direct comparison to water flowing in a pipe. Smaller pipe less water flow, so more impedance. Wider pipe more flow so less impedance.

 

[John-tyler]

thanx guys iam starting to understand so u want the impedance to be low on the tester

 

[davy_owen_88]

Yes, consider it like this.

There is a hallway with a fire alarm at the end. If there are 600 screaming women (ohms) standing around flapping their arms in the air then it's going to take me longer to calm them down, then push them aside to get to the alarm so the situation is going to be worse off.

Then consider that the hallway is empty, I'll get to the alarm much quicker and therefore the problem will the resolved far quicker.

 

[John-tyler]

thanx guys i undrestand now! cheers

 

[ricicle]

In layman's terms impedance is AC resistance with reactance thrown in as well (reactance is caused by inductive/capacitive effects)

Sorry not too laymanish but anyhow I'm off to bed