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This is a working repository for development of NMRA DCC Standards, Recommended Practices, Technical Notes, and other documents.
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TN-9.1.2 Review (Nov 1, 2020 Draft) #41

Open bakerstu opened 3 years ago

bakerstu commented 3 years ago

These are review comments that came in over email.

Line 68, Section 2.2.2.2: Add this sentence at the end of the first paragraph:

A silicon diode must be connected across the 6N137 in reverse (cathode to anode, anode to cathode) to keep the 6N137 5V reverse polarity from being exceeded.

Line 112, Repeater: Add this sentence to the end of the first paragraph:

These connections are labeled DCC INPUT.

Line 115, Repeater: Add this sentence to the end of the second paragraph:

These connections are labeled DCC OUTPUT.

bakerstu commented 3 years ago

...additional comments via email...

Table 1 title line lists two times 422 instead of 422 and 485.

2.2.1.4 Power Station Common There is a difference in the electrical standards in the USA and Europe. While - to my knowledge - in the USA model railroads have to be grounded to the security earth, in Europe model railroads are classified as toy and as such need to be floating. All primary power supplies need to be double insulted and shall not have a security earth connection at the power plug.

I'm pleased that the standard and TN allow both setups.

KQRR4449 commented 3 years ago

Hi Gang,

The United States allows double insulated devices as well. The common referred to in the standard does not need to be connected to earth ground.

Sincerely,

Ken West

On Mon, Jan 11, 2021, 4:10 PM Stuart W Baker notifications@github.com wrote:

...additional comments via email...

Table 1 title line lists two times 422 instead of 422 and 485.

2.2.1.4 Power Station Common There is a difference in the electrical standards in the USA and Europe. While - to my knowledge - in the USA model railroads have to be grounded to the security earth, in Europe model railroads are classified as toy and as such need to be floating. All primary power supplies need to be double insulted and shall not have a security earth connection at the power plug.

I'm pleased that the standard and TN allow both setups.

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bakerstu commented 3 years ago

These are review comments that came in over email.

Line 68, Section 2.2.2.2: Add this sentence at the end of the first paragraph:

A silicon diode must be connected across the 6N137 in reverse (cathode to anode, anode to cathode) to keep the 6N137 5V reverse polarity from being exceeded.

Added

Line 112, Repeater: Add this sentence to the end of the first paragraph:

These connections are labeled DCC INPUT.

Line 115, Repeater: Add this sentence to the end of the second paragraph:

These connections are labeled DCC OUTPUT.

I've added something similar, please review.

bakerstu commented 3 years ago

...additional comments via email...

Table 1 title line lists two times 422 instead of 422 and 485.

Fixed.

2.2.1.4 Power Station Common There is a difference in the electrical standards in the USA and Europe. While - to my knowledge - in the USA model railroads have to be grounded to the security earth, in Europe model railroads are classified as toy and as such need to be floating. All primary power supplies need to be double insulted and shall not have a security earth connection at the power plug.

Model railroads in the USA do not need to be connected to Earth Ground. A Power Station Common is NOT the same as Earth Ground. In fact, using Earth Ground as a Power Station Common can be extremely unsafe, though I know of one manufacturer recommending it.

If the Power Station Common is connected to Earth Ground, it is critical that it be a SINGLE point of connection. The reason for this is that if the Power Station Common becomes a lower impedance path than the Earth Ground wire in the "house" wiring, fault currents will now flow through the model railroad wiring, which is not typically inspected by a qualified electrician, and does not typically meet the necessary building codes for a proper Earth Ground.

I'm pleased that the standard and TN allow both setups.

Good, this was intentional.