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Telephone Line, Red Wire, Ringing Voltage to Ground
Hi,
I have used a Fluke DMM with a Max/Min capture feature to measure the ringing voltage, not only red to green, but also red to ground (and green to ground). To my surprise, the red wire to ground ringing voltage (some telephone equipment on line) was 93.2 VAC !! The green wire to ground ringing voltage was 36.4VAC. Note: Telephones are ringing. Is this normal? Thank You in advance, John |
Telephone Line, Red Wire, Ringing Voltage to Ground
https://www.sandman.com/knowledgebas...-tech-bulletin
The internet is your friend. Peter Wieck Melrose Park, PA |
Telephone Line, Red Wire, Ringing Voltage to Ground
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Telephone Line, Red Wire, Ringing Voltage to Ground
On Mon, 20 Jan 2020 09:34:17 -0800 (PST), "
wrote: https://www.sandman.com/knowledgebas...-tech-bulletin The internet is your friend. Peter Wieck Melrose Park, PA Hi, I saw that "sandman", and other places on the web, but it did NOT say anything about the ringing voltages from red to ground or green to ground. That is why I made this post. John |
Telephone Line, Red Wire, Ringing Voltage to Ground
On Tuesday, January 21, 2020 at 7:26:22 AM UTC-5,
Hi, I saw that "sandman", and other places on the web, but it did NOT say anything about the ringing voltages from red to ground or green to ground.. That is why I made this post. a) Most POTS phones are two-wire these days. b) In most cases, the ground (separate) does not leave the demarc. c) Both the the "red" and the "green" are not at ground potential, *and* also not at the same potential to each other. Therefore the 'ring voltage' will be different from each to ground than between the POTS conductors. Which was covered in the article linked, but not with these same words. Read carefully the section on measuring AC over DC, and that should help you understand. Peter Wieck Melrose Park, PA |
Telephone Line, Red Wire, Ringing Voltage to Ground
Try putting a 1K resistor in parallel with the meter. I predict that you will get something close to zero for both wires to your earth ground for both ac and dc measurements.
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Telephone Line, Red Wire, Ringing Voltage to Ground
On Monday, January 20, 2020 at 1:15:44 PM UTC-5, Fox's Mercantile wrote:
On 1/20/20 11:34 AM, wrote: https://www.sandman.com/knowledgebas...-tech-bulletin The internet is your friend. Peter Wieck Melrose Park, PA Wonderful explanation. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com And it contained this little gem, which you all probably knew, but was a surprise to me: ***** A very good technical explanation for variances in AC voltage measurements was put out by Agilent (formerly HP), who makes their own meters ranging from handhelds to lab equipment. I was amazed to read that meter manufacturers calculate True RMS by reading the heat produced by the AC voltage (4 page PDF file): ***** I could not get to the Agilent PDF just now. |
Telephone Line, Red Wire, Ringing Voltage to Ground
On Thursday, January 23, 2020 at 1:57:31 PM UTC-5, Tim R wrote:
On Monday, January 20, 2020 at 1:15:44 PM UTC-5, Fox's Mercantile wrote: On 1/20/20 11:34 AM, wrote: https://www.sandman.com/knowledgebas...-tech-bulletin The internet is your friend. Peter Wieck Melrose Park, PA Wonderful explanation. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com And it contained this little gem, which you all probably knew, but was a surprise to me: ***** A very good technical explanation for variances in AC voltage measurements was put out by Agilent (formerly HP), who makes their own meters ranging from handhelds to lab equipment. I was amazed to read that meter manufacturers calculate True RMS by reading the heat produced by the AC voltage (4 page PDF file): ***** I could not get to the Agilent PDF just now. There are ICs that calculate RMS for test equipment. Agilent changed their name to Keysight several years ago. |
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