Netonix Forums

Hi

We're noticing high power consumption (120W+) on one end of one of our AirFiber links.
Only affecting one end of the link.
Power up via a WS-12-250-AC running f/w 1.4.2.

I've rebooted the radio but issue still persists.
Link is operating ok.
Other end of the link has expected consumption in and around the 40W mark.

What could be the issue here - cable run, radio?

Thanks
Colin

Most common reason for this is the current senors are damaged.

Excess ground current has been flowing across your Ethernet cable and burned out the current sensor.

Or your current sensor on that port was exposed to voltage > 60V but ground current is the most common reason.

it can also be from a failed current sensor.

You will need to RMA the unit to determine if the sensor failed which will be repaired under warranty or damaged which will be repaired for a fee.

Most common reason for ground current damage is you do not have the electrical service ground rods bonded to the tower ground rods. This means so you have a heavy (at least #2) wire that runs from the electrical service ground rods to the the tower ground rods.

Another thing people do not do is run dedicated #2 green ground wire from the tower grounding system to a bus bar where your antennas are located then a #6 ground wire to each antenna mount and also to any ground lug a radio may have such as the ground lug on the AF24 radio. You then need to make sure you added a sufficient service loop in your Ethernet cable so that the Ethernet path to ground is at least 10% longer to ground then the intended ground path you are proving so that any static charge that builds up on your tower will go to ground through the ground cable and not your Ethernet cable and thus through your switch.

If this is ground current flow this time the switch was damaged, next time it could be the Ethernet port in the AF24 which is $1500 to $3000 device that gets damaged not a $300 device. I lost a $3000 AF24HD last year due to ground current flow which you can read about in the posts below.

Here are some good posts on grounding:
viewtopic.php?f=30&t=1816
viewtopic.php?f=30&t=188
viewtopic.php?f=30&t=1429
viewtopic.php?f=17&t=1786&start=30#p13447
https://community.ubnt.com/t5/airFiber/ ... rue#M31070

Here are a ton of posts where we discuss blow current sensors:
search.php?keywords=%2Bcurrent+%2Bsensor+%2Bdamage&terms=all&author=sirhc&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

As another intensive to check your grounding the most probable reason that single port sensors were damaged is that cable path to your AF24 radio must be the most attractive path prevented.

So if it is ground current flow from the service ground to the tower ground the ground current entering the switch to get to ground found that particular cable as the shortest leas resistant path to the tower ground and thus that excess ground current is also flowing through your AF24 Ethernet port and over time can damage it.

Or of this was a Static or ESD charge (doubt was ESD from a near strike but more probable static generated by wind blowing across your tower and antenna the best path to earth ground was found to follow the Ethernet cable down which mean you do not have a dedicated ground path to Earth ground that is shorter and has less resistance than the Ethernet path.

OR THE CURRENT SENSOR FAILED, IT DOES HAPPEN - ALTHOUGH VERY RARELY.

Our policy is that is if there is no visible damage to the board we will repair under warranty free even though damage is not always visible.

If the current sensor is damaged "most" times there is visible damage where the IC is blow out and there is a black mark around it from all the current or excessive voltage.

This is why we error on the side of the customer and require visible proof of damage not to cover under warranty which we provide a picture of the damage and return the board to you with the repaired switch.

We are currently modifying our switches to handle up to 40+ amps of current flow without taking damage depending on the model and how many cables are in play but remember if one cable presents itself as a better path to ground current will pick that cable path over the others first. But then the next device to fail from this current flow will be the radio your powering. So now people who do not practice good grounding may find themselves with a fully functional switch but a dead radio 200 feet in the air as it failed under the stress of excessive ground current flow.

Look, Cell carriers learned a long time ago the value of spending some time and money insuring they have less than 5 Ohms of ground potential between any too points on their site under normal conditions so that under adverse conditions this potential difference never becomes high enough to cause damage bu ground flow current going across lines they do not want it to.
Go take a good look at a cell site and take note of all the ground cables running everywhere and even anything metal on the site is bonded to this ground plain including metal light posts, fences, gates, just about anything metal has a ground wire running to it.