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PostPosted: August 22nd, 2018, 8:14 pm 
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I completed the project. And I have an observation that I need to run by the experts.
Am I right that the concept of the "neutral" goes away on the secondary side of the xformers.
On the primary side neutral is connected to ground at the mains box.
On the secondary side I get voltage reading both between what would be considered the neutral and ground and also between what would be considered the hot and ground.
I am trying to understand what is being presented to the load is not necessarily what was intended by the designers of the load.
Just thinking out loud.


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PostPosted: August 23rd, 2018, 8:57 am 
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Pelliott321 wrote:
I completed the project. And I have an observation that I need to run by the experts.
Am I right that the concept of the "neutral" goes away on the secondary side of the xformers.
On the primary side neutral is connected to ground at the mains box.
On the secondary side I get voltage reading both between what would be considered the neutral and ground and also between what would be considered the hot and ground.
I am trying to understand what is being presented to the load is not necessarily what was intended by the designers of the load.
Just thinking out loud.



I'll give it a shot. The unit you bought was designed for data systems and plugged into an isolated ground receptacle. That means you would have neutral (white), hot (black), ground bond (typically bare), and the isolated ground (green). You may have seen the orange receptacles during your travels. The transformer secondary side should (if having an electrostatic isolation shield between the windings) should have the secondary winding labeled as if the feed was coming direct from the panel-board and a ground bond. Since the shield is layered between the windings I expect that it could get induced voltage. Any other opinions are welcome.


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Isolation Transformer Schematic.jpg
Isolation Transformer Schematic.jpg [ 53 KiB | Viewed 9288 times ]

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PostPosted: August 23rd, 2018, 10:07 am 
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Thanks Walt
That confirms what I found.
"Isolated Ground" term is also a bit of confusion for me. To me it sounds like the ground is separate from the neutral. Isn't that always the case at the socket. The only place neutral and ground are bonded is at the mains box.


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PostPosted: August 23rd, 2018, 10:48 am 
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Re: isolated ground. What you wrote is true, Paul. The confusion lies in that an "isolated ground" receptacle has an insulated green ground wire running from the U-ground receptacle contacts to the main bonding jumper (in the panel). This grounding conductor is "isolated" from the "safety ground" that is the outer sheath of an armored cable, the bare conductor of NM (Romex), or the conduit enclosing the circuit conductors. That "safety ground" wire connects all of the metallic elements of the wiring system to ground potential. In a normal receptacle, it also connects to the u-ground contact.

The purpose of the isolated ground is to isolate the load (data processing usually) from noise generated by other equipment on the circuit, or connected to the grounding system downstream of the main bonding jumper while still providing the drain & safety connection to the isolated ground load.

The thought here being that the main bonding jumper is a low impedance connection to "ground" and that noise should be virtually non-existent at this point, because it is shunted to ground. Reality is a bit different, as we are all aware.

The better solution IMHO is to use an electrostatically shielded 240V input, 120V output transformer on a dedicated circuit (more than one if you are like Tom P. with thousands of watts of amplification), then connect the grounded conductor of the secondary to the household ground, whether it be cold water, building steel of (in a newer home) the Ufer (foundation) ground. In the last scenario, overcurrent protection on the secondary is a must. In a high wattage situation, a 30 ampere 2-pole breaker from the house CBP could supply a 5kVA 240/120 transformer. The secondary of that transformer could deliver ~40 amperes @ 120 volts, so one could use 2 or more separate circuits to feed amp(s) on one circuit, preamps, tuners, DACs, turntables, etc. on another. ANY high wattage device (like a 2000 watt amp) should be on its own circuit to avoid causing voltage fluctuations in the circuit feeding the other gear (a HUGE, oversized, transformer helps here as well).

Is that confusing enough? LOL, it's clear to me since I kinda live this stuff, but if anyone is interested, I'd be happy to chat and help out.

Stuart


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PostPosted: August 23rd, 2018, 10:50 am 
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Pelliott321 wrote:
Thanks Walt
That confirms what I found.
"Isolated Ground" term is also a bit of confusion for me. To me it sounds like the ground is separate from the neutral. Isn't that always the case at the socket. The only place neutral and ground are bonded is at the mains box.

An isolated ground receptacle has two grounds. The isolated one to the u-ground and a second one to the yoke. The neutral IS connected to the ground at the panel, but the ground should only be carrying fault current in the event of a short to ground.


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PostPosted: August 23rd, 2018, 1:58 pm 
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Stuart Polansky wrote:
Re: isolated ground. What you wrote is true, Paul. The confusion lies in that an "isolated ground" receptacle has an insulated green ground wire running from the U-ground receptacle contacts to the main bonding jumper (in the panel). This grounding conductor is "isolated" from the "safety ground" that is the outer sheath of an armored cable, the bare conductor of NM (Romex), or the conduit enclosing the circuit conductors. That "safety ground" wire connects all of the metallic elements of the wiring system to ground potential. In a normal receptacle, it also connects to the u-ground contact.

The purpose of the isolated ground is to isolate the load (data processing usually) from noise generated by other equipment on the circuit, or connected to the grounding system downstream of the main bonding jumper while still providing the drain & safety connection to the isolated ground load.

The thought here being that the main bonding jumper is a low impedance connection to "ground" and that noise should be virtually non-existent at this point, because it is shunted to ground. Reality is a bit different, as we are all aware.

The better solution IMHO is to use an electrostatically shielded 240V input, 120V output transformer on a dedicated circuit (more than one if you are like Tom P. with thousands of watts of amplification), then connect the grounded conductor of the secondary to the household ground, whether it be cold water, building steel of (in a newer home) the Ufer (foundation) ground. In the last scenario, overcurrent protection on the secondary is a must. In a high wattage situation, a 30 ampere 2-pole breaker from the house CBP could supply a 5kVA 240/120 transformer. The secondary of that transformer could deliver ~40 amperes @ 120 volts, so one could use 2 or more separate circuits to feed amp(s) on one circuit, preamps, tuners, DACs, turntables, etc. on another. ANY high wattage device (like a 2000 watt amp) should be on its own circuit to avoid causing voltage fluctuations in the circuit feeding the other gear (a HUGE, oversized, transformer helps here as well).

Is that confusing enough? LOL, it's clear to me since I kinda live this stuff, but if anyone is interested, I'd be happy to chat and help out.

Stuart



Steve nailed it. Although the audio industry has a way to simplify things yet make promises they can't keep for marketing purposes. I would not give up my isolation transformer. Yet I tried a big-ass transformer for my power amps. in the past and it darkened the sound -- it kind of smothered the sound. You live and you learn.

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PostPosted: September 1st, 2018, 1:03 pm 
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Stuart Polansky wrote:
Re: isolated ground. What you wrote is true, Paul. The confusion lies in that an "isolated ground" receptacle has an insulated green ground wire running from the U-ground receptacle contacts to the main bonding jumper (in the panel). This grounding conductor is "isolated" from the "safety ground" that is the outer sheath of an armored cable, the bare conductor of NM (Romex), or the conduit enclosing the circuit conductors. That "safety ground" wire connects all of the metallic elements of the wiring system to ground potential. In a normal receptacle, it also connects to the u-ground contact.

The purpose of the isolated ground is to isolate the load (data processing usually) from noise generated by other equipment on the circuit, or connected to the grounding system downstream of the main bonding jumper while still providing the drain & safety connection to the isolated ground load.

The thought here being that the main bonding jumper is a low impedance connection to "ground" and that noise should be virtually non-existent at this point, because it is shunted to ground. Reality is a bit different, as we are all aware.

The better solution IMHO is to use an electrostatically shielded 240V input, 120V output transformer on a dedicated circuit (more than one if you are like Tom P. with thousands of watts of amplification), then connect the grounded conductor of the secondary to the household ground, whether it be cold water, building steel of (in a newer home) the Ufer (foundation) ground. In the last scenario, overcurrent protection on the secondary is a must. In a high wattage situation, a 30 ampere 2-pole breaker from the house CBP could supply a 5kVA 240/120 transformer. The secondary of that transformer could deliver ~40 amperes @ 120 volts, so one could use 2 or more separate circuits to feed amp(s) on one circuit, preamps, tuners, DACs, turntables, etc. on another. ANY high wattage device (like a 2000 watt amp) should be on its own circuit to avoid causing voltage fluctuations in the circuit feeding the other gear (a HUGE, oversized, transformer helps here as well).

Is that confusing enough? LOL, it's clear to me since I kinda live this stuff, but if anyone is interested, I'd be happy to chat and help out.

Stuart


Actually, as far as capacity, I run my whole system with all amps and other equipment on one shared 15 amp branch circuit. I want only one line to minimize ground loops. With the dynamic range of music plus the large internal storage capacity of the power supplies in all the equipment, I have never tripped a breaker. The internal storage flattens out the spikes in the input current requirements on the mains. However with all that equipment, if I did not have a soft start circuit I would probably pull the distribution box off the wall when I turned the system on.


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PostPosted: September 1st, 2018, 5:28 pm 
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I want to add surge protection. Want to fully understand MOV's.
Been reading and some are touting that the protection should be closest to the source (mains coming in) as close to load. They claim the clamping voltage is lower this way. I do not understand this. One showed that the clamping voltage was in the 500's when the protection was at the mains and in the 800's when at the load. Having whole house protection would have the advantage of protecting all TV's, computers and met sound system.
Can one have too many MOV's. They supposed to be out of the circuit until they fire.


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PostPosted: September 7th, 2018, 11:00 am 
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I use a 75lb 15A isolation tranformer on my source components, it also has non-sacrificial surge protection (no MOV).

For my amps, I use a 20A BrickWall non-MOV surge protector that is mounted in it's own little panel box near my main electrical box in the basement. It does not have a significant impact on audio quality, some might say a bit cleaner sounding while others might pejoratively describe it as a bit more polite. But it does provide excellent protection and cost less than $300.

I would prefer to plug everything right into the wall with no surge or isolation but with the crazy thunderstorms we have been getting (and with the influx of LED lighting), I figured that some filtering and protection is really warranted. Just an option to MOVs which will require replacement at some point.


Pelliott321 wrote:
I want to add surge protection. Want to fully understand MOV's.
Been reading and some are touting that the protection should be closest to the source (mains coming in) as close to load. They claim the clamping voltage is lower this way. I do not understand this. One showed that the clamping voltage was in the 500's when the protection was at the mains and in the 800's when at the load. Having whole house protection would have the advantage of protecting all TV's, computers and met sound system.
Can one have too many MOV's. They supposed to be out of the circuit until they fire.


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PostPosted: September 7th, 2018, 11:10 am 
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I understand that MOV are sacrificial. I was not aware of any other types
please enlighten


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