Questions tagged [earth]

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98 views

Earth alternative

I'm designing an industrial machine which is AC motor derived. There are sensitive analog sensors (e.g. Load cell) in the system and in the user's site, Unfortunately earth connection is not ...
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1answer
7k views

Why are CT's(Current Transformers) on an ammeter / energy meter connected to ground?

It's understandable that a CT, needs to be shorted (or a burden resistor) if there's nothing connected to its output, otherwise it would work as a step-up transformer. But why is it that energy ...
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2answers
394 views

Earth connection missing on electric circuit, getting lots of noise with audio equipment

I have a question today that possibly crosses to another website, but i'm interested in your expertise here. It's more or less about music, but also about noise and electric current. Basically, I ...
3
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1answer
3k views

Grounding the chassis with capacitor

My question involves chassis grounding to earth ground. My PCB circuit is a simple signal generator using a microcontroller. It has a separate 'ground' from earth ground, supplied by a floating 5VDC ...
3
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1answer
322 views

Why conceptually we connect circuits to earth but in reality that doesn't really work?

This question is best seen with an image: Above we can see two equivalent representations of a circuit, on the left side we have a voltage source closed-loop connected to a Resistance (R), and on the ...
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2answers
307 views

Can I use a double insulated power supply with a metal framed sculpture with LEDs

I have built a tree shaped wire framed sculpture with LED lighting. The LEDs each have a positive supply to the anode via an insulated wire and resistor, and the cathodes are connected directly to the ...
3
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1answer
388 views

Why does the Earth's electric field affect things so little?

Starting here: http://hypertextbook.com/facts/1998/TreshaEdwards.shtml "Over land the average electric field is about 120 V/m …. Assuming an exponential increase of the conductivity with altitude, ...
2
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1answer
349 views

What were to happen if I short-circuited electricity generated by a power plant to the Earth?

I'm not sure how to word this better, so I hope this makes sense. Let's say theoretically that I connected a cable from the hot side of the power lines that run along the road to a stake in the ground,...
2
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1answer
140 views

Connection between metal enclosure and 0V in industrial system?

I have been testing an industrial system. I have developed a test device to properly test this industrial system. I am currently finalizing the test device and have put it in an enclosure to EMC proof ...
3
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1answer
872 views

Oscilloscope ground clips sparks while connecting to power supply

Oscilloscope ground clips sparks while connecting to power supply ground. I do understand The clip is connected to earth ground. But why does it not spark when I am powering a circuit of the supply?
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1answer
498 views

Which configurations are safe to use an oscilloscope?

A USB device is connected to a Laptop PC. Laptop PC has a ground earthed power supply. Oscilloscope's negative lead is connected to ground via its own power supply. Oscilloscope's negative lead is ...
4
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1answer
349 views

local/bench earth leakage for testing mains electronics

I sometimes find myself testing switch mode power supplies and such that I have repaired, and often some undetected fault causes them to trip the earth leakage breaker on the distribution board when ...
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0answers
176 views

Earth Loop Impedance Meters; Difference between 3 lead (L-N-E) and 2 lead (L-N/E)?

In our company we use various different brands / models of ELI meters. Some have three leads, live, neutral and earth, and some have only two leads, one live and one neutral/earth combined. Can ...
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2answers
237 views

Should I ground my case

I built up a LM317 power supply which is working great. I have moved it into a large case as I am now powering it off 240VAC (fused) down to 18VAC then rectified into the power supply. Which is going ...