Ethernet over voltage protector

I got 10BASE-T and 100BASE-TX Ethernet running through this over voltage protector. They are nor designed for faster data rate.

Those protectors are designed to protect two 100 ohms wire pairs. They are designed to work well up to 60 MHz signal and have low capacitance (around 30 pF between wire pair wires).

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Links to more information on Ethernet over voltage protection:
https://www.epanorama.net/blog/2016/07/14/rj-45-ethernet-surge-protection/
https://www.epanorama.net/blog/2018/12/02/rj-45-surge-protector-teardown/

6 Comments

  1. Tomi Engdahl says:

    https://www.quora.com/What-voltage-do-Cat5-Cat6-Ethernet-cables-typically-operate-at

    Kjell Lindberg
    , Electronics Designer (1985-present)
    Updated 7 months ago · Author has 2.6K answers and 1.3M answer views

    Ordinary Ethernet has a +-1.5V signal level transitions, with typical 1:1 transformers. The effect that is used is that it is differential. So the needed differential signaling needs to be higher than half of 1.24V so about 0.4V RMS to 1.5V RMS. At least for all equipment that I have designed.

    Then on top of that PoE could exist but that is a DC voltage from 24 to 48V positive ground/reference (I do hate that part of the specification, crazy telecom influenced part).

    Category of cable isn’t relevant; cable category has to do with reduction in the amount of crosstalk among the wires in the cable.

    Google search found this on Quora:

    “Normal Ethernet will have up to 12V with a few milliamps of current for communication. For Power over Ethernet devices (POE), the voltage can be as high as 48V with up to 5 Amps of current.”

    Most Ethernet is 100 base Tx. Ethernet is a differential signal, magnetically isolated by a 1:1 transformer at each end. The differential signal maximum across a 100 ohm load (the other transformer) is approximately 1 volt peak differential

    Reply
  2. Tomi Engdahl says:

    https://networkengineering.stackexchange.com/questions/43734/what-is-the-voltage-used-in-ethernet-lines-utp-cables

    From the IEEE 802.3-2008 document borrowed from the official IEE 802.3 get page – but it seems it is no more freely available.

    7.4.1.3 AC common-mode output voltage
    The magnitude of the ac component of the common-mode output voltage of the driver, measured between the midpoint of a test load consisting of a pair of matched 39 > Ω ± 1% resistors and circuit VC, as shown in Figure 7–13, shall not exceed 2.5 V peak from 30 Hz to 40 kHz and 160 mV peak from 40 kHz to BR.

    7.4.1.4 Differential output voltage, open circuit
    The differential output voltage into an open circuit, measured at the interface connector of the driving unit, shall not exceed 13 V peak.

    7.4.1.5 DC common-mode output voltage
    The magnitude of the dc component of the common-mode output voltage of the driver, measured between the midpoint of a test load consisting of a pair of matched 39 Ω ± 1% resistors and circuit VC, as shown in Figure 7–13, shall not exceed 5.5 V.

    Newer standards may have different limits, but since they are usually retro-compatible, they must not have changed much. I dug trough a few of them but didn’t found specifications that contradict those above.

    The 802.3bq-2016: Physical Layer and Management Parameters for 25 Gb/s and 40 Gb/s Operation, Types 25GBASE-T and 40GBASE-T document has the table:

    n which you can find a Differential-mode voltage of < 2.4 + 19.68 (f / 30) mVpp close enough to 2.5V. (Vpp stands for the voltage differential peak-to-peak, i.e. difference between the lowest and highest voltage in a period.)

    There's another voltage involved, when using Power Over Ethernet (POE), which range from 37 to 57V.

    Reply
  3. Johna says:

    All Ethernet connections shall have a 1500V insulation capability and in some equipment, it is raised to 2500V.

    Reply

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