Elements between PCB-GND and Mains Earth in SolidState Power Amps - How to Calculate? - Page 2 - diyAudio
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Old 17th June 2012, 05:47 PM   #11
djk is offline djk
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Patent US20040264712 - Method and apparatus for eliminating noise in an electrical circuit - Google Patents
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Old 17th June 2012, 06:18 PM   #12
AndrewT is online now AndrewT  Scotland
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Dj, post9,
what is the message?
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Old 17th June 2012, 06:40 PM   #13
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"gnd loop breaker" safety issues may be practically improved by using anti-parallel power diodes rated for enough current to blow fuses or breakers

allows a good fraction of the diode's Vf to be "blocked" by the high impedance to reduce hum but carries the 10s-100 of A for the time required to blow fuse or open breakers in the event of a fault to the mains with only a few V clamping V

may not satisfy some safety agency rules - they aren't all consistent or flexible

in Intrinsic Safety rules that cover chemical plant safety 2x parallel diodes rated with continuous current equal to any fusing in the system are considered "safe" - the diodes may be assumed to only fail shorted in the safety analysis


I don't buy line xfmr that don't meet double/reinforced insulation standards, 4kV Hipot for domestic mains V - then the output side can safely float

Last edited by jcx; 17th June 2012 at 06:52 PM.
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Old 18th June 2012, 09:56 AM   #14
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Quote:
Originally Posted by AndrewT View Post
Post 1
The pic shows the Audio Ground connected to the Safety Earth via a Disconnecting Network of 100r//0u22F.

TEST that arrangement.

I bet
1.) the Disconnecting Network blows up.
2.) that the mains fuse may remain intact.
3.) that if the mains fuse remains intact that the potentially fatal result will be MAINS voltage on the Chassis.

Tief, you have made a grave mistake placing that dangerous schematic on the Forum where every Member can see it.

Please ask to have the dangerously wired pic removed before someone gets killed.
Please let me know which post # and the URL (or mean you post #1 here? - for that case please note: this schematic isn't from me.)
What means "via a Disconnecting Network" (maybe a ground lift switch?)??


BTW - for me all kinds of wiring (resp. all audio devices with such wiring) with additional mains earth are absolutely dangerously wired. Until now I don't understand, why there are not only 2-wired manis connectors without earth and additional double insulation standards by transformer and wiring by commercial products. The main deficiency is actually the absense of double insulation standards by transformer at most models from vintage and currently models.
Imagine what happens, if the mains earth connection is interrupted within the amplifier or whatever by shorting the hot mains wire "L" with the cabinet at the same time (e. h. when an insulation fault is present on the transformer), and your child grasps with one hand on the amplifier and with the other to a water tap ...
And please note: what happens in such cases is independend from the question of this topic here.

Last edited by tiefbassuebertr; 18th June 2012 at 10:26 AM.
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Old 18th June 2012, 10:28 AM   #15
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Old 18th June 2012, 11:39 AM   #16
AndrewT is online now AndrewT  Scotland
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Originally Posted by AndrewT
Quote:
Post 1
The pic
Quote:
Originally Posted by tiefbassuebertr View Post
Please let me know which post #
imagine buying an isolation transformer powered 3 bar room heater or a isolation transformer powered hair straightening tongs or a etc.....
How much extra would each of these cost?
Would they still sell?

The standards available for safe manufacture of electrical equipment cover many and every type of device. The manufacturer chooses the type of safety protection appropriate to the device they manufacture.
That range of standards must include both for Class I and Class II and others.

We, as amateurs, without the resources to design and build and test and guarantee double insulated equipment, have no choice but to do our best with Class I protection. We connect all external parts to Safety Earth and we connect that Safety Earth to Protective Earth (PE).
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Old 18th June 2012, 12:58 PM   #17
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Quote:
Originally Posted by AndrewT View Post
Originally Posted by AndrewT imagine buying an isolation transformer powered 3 bar room heater or a isolation transformer powered hair straightening tongs or a etc.....
How much extra would each of these cost?
Would they still sell?

The standards available for safe manufacture of electrical equipment cover many and every type of device. The manufacturer chooses the type of safety protection appropriate to the device they manufacture.
That range of standards must include both for Class I and Class II and others.

We, as amateurs, without the resources to design and build and test and guarantee double insulated equipment, have no choice but to do our best with Class I protection. We connect all external parts to Safety Earth and we connect that Safety Earth to Protective Earth (PE).
I don't understand the marked terms. First, my English is too poor for it, and secondly I talk about "protection class II" transformers and don't talk about additional isolation (insulation) transformers.

However - both professionals and amateurs should use transformers in those kind as the following URLs shows:
Toroidal Lighting Transformers
http://www.tauscher-transformatoren....s/pdf/R_16.pdf
HAL-TRAFO 60VA - Halogentrafo 60 VA, 230V - 11,6 V bei reichelt elektronik
HAL-TRAFO K60VA - Halogentrafo 60 VA, 230V - 11,6 V, Klemmen bei reichelt elektronik
Then protection class II is present (tools in protection class II are completely insulated by a special insulation). Such transformers do not require earthing (only 2 wires for mains lead are necessary).
What about the costs? Not significant larger than by the use of class I transformers.

check out also this URL for basic informations concerning the various kinds of protection class
http://www.rohrlux.de/Html/gb_schutzarten.html

Last edited by tiefbassuebertr; 18th June 2012 at 01:12 PM.
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Old 18th June 2012, 01:03 PM   #18
AndrewT is online now AndrewT  Scotland
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Tief,
you still have that pic in post1.
Why don't you arrange for this potentially fatal wiring diagram to be removed?
Or at least get it altered to show a safe version of the wiring diagram.
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Old 18th June 2012, 01:24 PM   #19
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Quote:
Originally Posted by AndrewT View Post
Tief,
you still have that pic in post1.
Why don't you arrange for this potentially fatal wiring diagram to be removed?
Or at least get it altered to show a safe version of the wiring diagram.
Yes. I don't understand, why I should remove. Where is mentioned from me, that this is the right wiring kind?
OTOH, this kind of wiring you will find by a wide range of commercial products. For this reason I have posted this schematic as an example.
This schematic I have found several times online (have a look to various service manuals/schematics - e. g. Cyrus "ONE" and "TWO").
But in this case the uploaded schematic is to understand in context with the topic here, but under no circumstances as my favorite diy instructions.

Nevertheless I will send one of the moderators a PM to delete this schema because I cannot carry out this because I am not a moderator.
BTW - you don't read my posts carefully. Please explain this term:
"a Disconnecting Network"

Last edited by tiefbassuebertr; 18th June 2012 at 01:32 PM.
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Old 18th June 2012, 03:54 PM   #20
AndrewT is online now AndrewT  Scotland
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Quote:
Originally Posted by tiefbassuebertr View Post
Yes. I don't understand, ......................
BTW - you don't read my posts carefully. Please explain this term:
"a Disconnecting Network"
Post8
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