The Siren Board

Discussion of Outdoor Warning Systems
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PostPosted: Tue Mar 16, 2021 4:26 pm 
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Joined: Sat Mar 30, 2013 3:50 am
Posts: 1393
Real Name: Dennis Seldon
YouTube Username: DJ2226
Location: Columbus, Georgia
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Hey everyone. Over the past couple of years, I've slowed down the rate at which I record sirens in Columbus. Usually, when I do it now it's to document any system failures I happen to come across or anything new that pops up in the system such as our two new WPS-2910s that replaced the 2810s that went yeet due to a construction worker backing into one and a tornado ripping the head off of the other.

This "voice only" thing seems to be a bit of a trend in our system that usually happens after one of the sirens has been malfunctioning due to bad batteries. Every siren on the system is equipped with a remote terminal unit that functions as an external radio. The RTU and controller both are battery operated and have voltage thresholds that they operate within. To avoid damaging the equipment the siren controller and RTU shut off if the voltage goes too high to too low. Apparently, the low voltage threshold on both is different with the controller's being lower at around 18VDC with the RTU's being probably somewhere in the neighborhood of 19-20VDC. What seems to be happening is as the batteries start to lose their capacity over the years the voltage drop causes the RTU to drop out while the siren is able to continue running. This leads to the siren running for 3 minutes in whatever tone, or voice in this case, the RTU left off. In every case, the sirens that run wild for the test like this eventually get to the point where they start to die mid-way through the tone from the battery voltage dropping because of the decreasing capacity. What you're seeing in the video appears to be the voltage falling off a cliff from the capacity loss, and the only thing the RTU can do is make the siren talk.

I've emailed our EMA about the siren a couple of weeks ago when it was still running wild and starting to die mid-cycle after about 50 seconds of wail. This was taken the following week. The progression was pretty quick. You can hear the voice get garbled as the siren tries to talk. That's typical with pretty much every manufacturer's products when operating on low voltage like this. Interestingly enough before the system had its radios upgraded the older RTUs wouldn't do this. They apparently had a much lower voltage cutoff. Back then the sirens would attempt to run every tone and do every voice. I have plenty of footage of them doing this on my channel prior to 2016.

Proud owner of a Model 1.
DJ2226's YouTube Page

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