Tarana calls it an inductor. It is fairly large, maybe a foot long, far more substantial than the typical ferrite core you might see on a dc power supply for consumer electronics for example.
>From their bulletin: Issue Based on the field data from customer site visits and Tarana’s internal testing it has been determined that only Transtector’s DC Defender PN: 1101-1110 Model DC Defender 48-5 SPD is properly coordinated with the base node ( BN). Other SPD’s used by customers may have response times too slow to protect the BN which can result in an improperly rated or mismatched SPD failing to activate in time. This could allow excessive surge energy to pass through, potentially causing damage to the BN. This impacts all the models of G1 base nodes. Solution A new “coordination power cable” that includes two series inductors embedded within the cable assembly connecting the SPD to the G1 BN. This additional series inductance effectively forces the external SPD solution into conduction sooner than the G1 BN, thereby allowing the external SPD to do more of the protection work during a surge event. Towers get hit by lightning all the time without damage to the equipment if everything is built properly. Not every lightning strike is equal though; some are a couple orders of magnitude more powerful than the average strike, and will produce damage. Also, a direct hit to the equipment itself rather than the structure is obviously going to let the smoke out. I've been to a site after a big hit. The Verizon guy was also there and said his radio heads and his entire DC plant went up in smoke. The tower lighting control box at the base of the tower was blown open with the lid bent from an arc flash inside it. Our AC UPS in our cabinet at the base was fried, but all of our epmp APs on the tower were fine. We had some Tarana BN failures early on until we settled on combining MOV SPDs on the hybrid cable and an SASD SPD as close to the radio as possible, and have been fine since. If Tarana's new cable with inductors is a good idea, I think we should deploy it, it just seems like it's against what I've been taught about lightning protection, which is that you want everything to go up to the same potential, and back down again at the same time. I'm no EE though, so was curious what yall thought. On Wed, May 28, 2025 at 6:46 PM Adam Moffett <[email protected]> wrote: > By inductor do you mean a ferrite core? > > On Wed, May 28, 2025 at 6:01 PM castarritt <[email protected]> wrote: > >> Tarana is telling everyone to switch to a DC power cable for their radios >> that has a big inductor for surge suppression. Is that really a good idea >> though? We use a Transtector DC Defender (SASD based) SPD at each BN, and >> they want the inductor in between the SPD and the radio. If the only surge >> event that we needed to worry about was a voltage spike on the DC line, >> this might make sense, but that's not what happens when the tower is struck >> by lightning, right? The whole structure and the radio chassis/ground is >> getting energized when the site is struck, and my understanding is that the >> DC lines need to be brought to the same potential by the SPDs to avoid >> damage. Wouldn't putting an inductor on the DC line between the SPD and >> the radio be counter productive? >> -- >> AF mailing list >> [email protected] >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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