Author Topic: To float or not to float....  (Read 2956 times)

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Offline cybertronicifyTopic starter

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To float or not to float....
« on: September 04, 2014, 04:04:44 pm »
Hello people!

I was wondering what is the best option on my Korad KA3005D. It has +/- and Earth binding posts and should Earth be shorted out to GND? If you can, please explain to me what does floating ground mean and what does earthed ground mean.

Thanks!!

The Korad will be powered by a 110vac to 220vac transformer.

http://www.ebay.com/itm/Goldsource-STU-300-W-Watt-Step-Up-Down-110V-220V-Voltage-Converter-Transformer-/160733095687?pt=BI_Circuit_Breakers_Transformers&hash=item256c706707
 

Offline macboy

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Re: To float or not to float....
« Reply #1 on: September 04, 2014, 04:59:54 pm »
There is no correct answer to this question. A lot depends on what you will be powering with this power supply.

If it is a simple circuit with just this one power supply, and you won't be making measurements with a scope, then often, the - terminal is grounded so that the circuit ground is equal to earth ground.

If you use multiple supplies, then often, only one has a terminal grounded. This prevents ground loops. Same idea when measuring using an earth-ground-referenced instrument like an oscilloscope. The ground lead on the probe is directly connected to ground. If you float the circuit, then you can connect this to almost any reasonable point in the circuit, not just a 'ground'. But if you ground reference the power supply - terminal, then you must only connect the scope ground probe to a true ground. And even then, you are creating a ground loop which may or may not cause problems.
 

Offline Terabyte2007

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Re: To float or not to float....
« Reply #2 on: September 04, 2014, 06:52:34 pm »
In simple terms, a floating ground is relative to the circuit being used and does not necessarily always have to be 0V. A floating ground should not have a physical connection to an earth ground. An earth ground will always have an electrical path to the physical earth where voltages can be referenced and a return path for electricity.
Eric Haney, MCSE, EE, DMC-D
Electronics Designer, Prototype Builder
 

Offline cybertronicifyTopic starter

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Re: To float or not to float....
« Reply #3 on: September 04, 2014, 11:34:10 pm »
So ill just keep it grounded until i need to measure something or series the power supplies?
 

Offline sleemanj

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Re: To float or not to float....
« Reply #4 on: September 05, 2014, 04:43:09 am »
You should watch Dave's video on not blowing up your oscilloscope, the concepts are the same...



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Offline cybertronicifyTopic starter

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Re: To float or not to float....
« Reply #5 on: September 05, 2014, 11:55:17 am »
I've watched the video and it helped alot! I was wondering if i can use this as a isolation transformer.

http://www.ebay.com/itm/Goldsource-STU-300-W-Watt-Step-Up-Down-110V-220V-Voltage-Converter-Transformer-/160733095687?pt=BI_Circuit_Breakers_Transformers&hash=item256c706707

I have that step up/down and it does have a 110v in 110v out.
 


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