POE Interface IC in LoRa Gateway blown after lightning strike - Page 1
Forum section: electronics / projects

author: ebingaming
author_rank: Newbie
timestamp: March 26, 2025, 08:32:16 am
content: Greetings everyone,I'm new to the forums. Been watching EEVBlog's videos and lurking this forums for several time now, and found this to be a pretty welcoming place for all engineers. I'm pretty new to this online community forum thingy so please go easy on the biting!I am currently working in a particularly rainy area in Indonesia (kalo ada orang indo disini kaget juga). That wouldn't be a problem in it of itself, but with rain often comes lightning strikes. Our companies have a lot of outdoor industrial sensors and equipments, some of which have been damaged by lightning strikes (think of melting plastics, black charred PCBs, exploding ICs, etc etc.).One of my company's LoRaWAN gateway, branded Kerlink iStation (https://www.kerlink.com/product/wirnet-istation/) have been damaged by one of these lightning strikes. I highly suspected this because the last gateway transmission ping is during a rainstorm. As seen in the attached pictures, the only chip damaged (at least with physical inspection) is the Texas Instruments TPS23753A POE Interface chip. I should be able to order this chip online and I am confident that I can replace this using my hot air rework station. However, considering the frequency of similar incidents, I would like to prevent this in the future. Anyone have any ideas?Do you think there might be any fault in the grounding?Here are the installation details of the gateway prior to the lightning strike:Power supply:AC Wall Power => Stabilizer (PROLINK PVR1000D) => UPS (APC SMC1000I) => POE Injector (Ubiquiti POE-48-24W-G) => Surge Protector (Ubiquiti ETH-SP) => Very long cat6 cable (30-50m ish) => LoRaWAN Gateway (Kerlink iStation)The gateway is situated on top of a base station tower, alongside other equipments. Pictures are attachedLet me know if you need any more details.Cheers!

author: ftg
author_rank: Frequent Contributor
timestamp: March 26, 2025, 11:08:29 am
content: I would also suggest ordering new switching fet(s), new opto, new bridge rectifiers, new ESD protection for the Ethernet datalines, new TVS diode for the PoE (likely a 60V part) and one current shunt, as that shunt resistor also appears iffy.If the switch controller is gone, then the fet likely is as well.The current shunt for the fet looking unwell also points towards a dead fet.And if both of those are gone, stuff upstream of them is also suspect.As for prevention, maybe additional over voltage/surge protection at the device end of the line could help?Maybe look into what WISP folks do to protect their microwave links from lightning.

author: ebingaming
author_rank: Newbie
timestamp: March 27, 2025, 03:26:50 am
content: Nice find! Didn't even know resistors can be blown like that. I suppose i have to inspect more components to see the damages with my multimeter.I can add an additional protection beside the device (Something like this?https://wisp.net.au/tycon-tp-esp-10g-poe.html), right before ethernet socket in the gateway. But is there a way to prevent going up the tower whenever the protection device inevitably gets hit by lightning again (It costs the company and takes some time)?Also is it really the case that the lightning strike comes through the cat6 cable into the gateway? Why isn't the POE injector damaged? Or am i misunderstanding something here?

author: johansen
author_rank: Super Contributor
timestamp: March 27, 2025, 05:35:48 am
content: Quote from: ebingaming on March 27, 2025, 03:26:50 amthe lightning traveled 10 kilometers to get to the tower, it can handle a few more tens of meters. figuring out why one component is damaged and another isn't is a lot of work.perfect lightning protection is very hard because the current can continue in the range of 5,000 amps decaying to a few hundred, for as long as half a second. an eternity compared to the 20,000 amps in the first standard 8/20 micro seconds. -this is why you can't coil up a big inductor to block the voltage.how and where your lightning arrestors are grounded matters a lot.when the 20,000 amps flow (and that's a statistical average, it could be 50,000), if you have a 1 ohm resistance at the ground, suddenly your entire tower is at 20,000 volts relative to true ground, which means everything that is fault arrested to the tower, still has 20,000 volts on it looking for a place to go... and it will find one, and flow out away from the towera true air gapped system using a fiber optic line is the only way to make something lightning proof.

author: coppercone2
author_rank: Super Contributor
timestamp: March 27, 2025, 06:14:05 am
content: Like ok, in this pictureYou know what I mean the frequency inside the material looks goofy? It like decays slow. Like its charged to DC or something. Because the material is 1 cycle wide and it did not change polarity in the material. Is that just drawn bootleg? Does that have something to do with the speed of light in the material?

author: ebingaming
author_rank: Newbie
timestamp: March 29, 2025, 07:41:56 am
content: Quote from: johansen on March 27, 2025, 05:35:48 amThat's fair, I guess I have some things with the components to look for. Our company has holidays for 2 weeks, so I'm going to check the grounding by then. The gateway is placed on the tower among with other equipments (4G), so I should chat with them to ask how they are grounding stuff. There should be a way, because no way only our equipments get damaged while theirs are not.

author: IconicPCB
author_rank: Super Contributor
timestamp: March 29, 2025, 11:21:04 am
content: The protection does not work with lightning strikes. Often it does not work with near misses either. The energy levels are simply too high for protection solutions to work. One simple solution is to cut cables longer ...much longer than needed. Coil the excess cabling ( make an inductor ) and just let it slow down the leading edge of the pulse.There is no protection from lightning strike.