I saw something today that I’ve seen so many times before that I really just don’t understand.
I walked into a tower site ran by a local Public Safety organization. The site itself was, from an external standpoint fairly nice. The tower, building and guys were well fenced, and access was excellent. However, when we entered the small transmitter building, what we found was not quite what one would expect. Expecting nice, albeit small equipment racks with equipment neatly stacked and arranged in such a manner as to display a professional and well thought out system, we found instead, 2 AC powered console base stations, and one 12 volt powered base station. The console base stations were in cabinets and locked, a plus in my book, the other transmitter since it was substantially newer and 12 volt powered was sitting on a plywood shelf with the cheesy metal shelf brackets screwed into the wall.
Now don’t get me wrong. I understand that sometimes economy trumps everything else. Especially when working with public dollars. There always seems to be too much project at the end of the budget. The console base stations however, were not bolted to the floor. The grounding, coax and other infrastructure was neatly and professionally done. The 12 volt transmitter, even though on the shelf that it is, was neatly installed. Unfortunately, the location of this site is in a known earthquake zone. One good shake, and as the rhyme goes, they all go tumbling down.
No, what really crumbles my cookies was what these AC base stations were plugged into. One would expect, at a minimum, a properly grounded commercial line interactive UPS, complete with alarming. A quick note; I am NOT a DC power snob. While I do like DC power in certain applications, I do realize that AC power backup in the right situation(s) is appropriate, cost effective and reliable. But, when I walk into a Public Safety radio system site, I do not expect to see critical communications gear plugged into $150 UPS’s that someone picked up from the local office supply chain. The servers here at Praecom World Headquarters have better UPS on them than these radios.
I know the folks that installed and maintained the radios. Again, they are fine competent radio people. But radio people are not power people. Public safety people are not radio OR power people. Radio dealers are in the business to sell radios, and in today’s competitive world, anywhere they can cut costs they will.
I’m not disparaging the UPS manufacturer either. These are fine units for an office environment or supporting a small single server. I utilize a model very similar on the telephone system here in the office. The point I’m getting to is that it was the wrong application for the design.
You see, you have several dynamics all coming together that, if the moon and the stars are in proper alignment, something is going to go wrong. The site did have generator power, so hold time generally would not be a problem. The issue truly is that there lacks any visibility into the system. If the UPS were to fail, for any reason, AND the generator failed to start, all the poor dispatcher would know is that they were off the air. And these UPS’s do fail. Regularly, and when you least expect it.
As a comparison, also in this building is where the local RBOC has brought in a SONET terminal to drop out the circuits for the radios. The SONET terminal was in a small 19” rack, bolted to the floor. In a tray in the bottom of the rack was 4 nice 25 AH gel cell batteries and a float charger. The RBOC does have deeper pockets, but they also understand reliability and power. They have learned their lessons over 100 years of needing to provide service.
So the final advice is, whether you’re spending $250,000, $50,000 or $10,000 on a site take a little extra and design the power appropriately. A small commercial UPS and generator transfer panel is, in the grand scheme of things a small cost. And I guarantee you’ll sleep better at night. At a minimum, make sure you know what you’re asking for, and in the end, what you’re getting.