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Telecom Hut Monitoring: Choose and Buy the Best RTU

By Andrew Erickson

June 23, 2021


You might work in the telecommunications industry: a national telecom provider, a wireless provider, an independent telco, or an ISP. You could be in charge of keeping central offices and cell sites online. You might also work in telecom for a power utility or railroad or a county government (police/fire radio & 911 dispatch).

Telecom hut monitoring protects microwave radios in a very remote mountaintop site in Alaska
Telecom huts have to stay online 7x24x365 - a major demand given the extreme weather conditions at some sites (photo: a DPS client's site in Alaska)

In all of these cases, you have telecom huts to monitor in order to keep your service online. Each of those remote buildings contains thousands (or perhaps millions) of dollars of your valuable telecommunications equipment. Even more importantly, people (and sometimes their lives) depend on your service being reliable.

Companies and government agencies frequently call me and ask what RTU they need. Sometimes, they've seen a particular NetGuardian model on our website. If that's not a good fit for their actual requirements, I help them find a better RTU. Here are the key steps you should follow:

Step 1: List All of Your Telecom Hut Equipment

Before you can monitor your stuff, you need to know what stuff you have. The type and quantity of your gear determines precisely the type and quantity of RTU inputs that you need.

A TempDefender RTU monitoring LPG levels, temp, humidity, and AC current at a telecom building.
You need to survey your remote sites for the kind of equipment you have deployed. Only then can you consider what RTU to deploy. This hut is fairly small, so a medium-sized TempDefender G2 was ultimately selected.

As examples, here are some typical output configurations for different kinds of site equipment:

  • A Cummins / Generac generator with the "Power Zone Control Platform" might send MODBUS via TCP/IP (10/100Mbps)
  • The Fifteen-Relay Dry Contact Kit from Kohler provides, oddly enough, 15 relay-closure outputs (I might be competing with Kohler for the most boring product name scheme)
  • Newmar's Centurion (or equivalent Eltek) Rectifier System has a pair of relay outputs (one for "Minor Alarm" and one for "Major Alarm")
  • A Carrier WeatherMaker Single Package Large Rooftop Unit has an "Alert" relay and an "Alarm" relay.
  • The TLM (Tower Light Monitor) from Burk Technology has 10A isolated SPDT alarm output contacts
  • Generex BACS battery monitoring system, which is reporting directly to the Radix BMS platform.

As you can see, each piece of equipment has a different number of outputs. You can tally all of those up to get a sense of your future RTU's required inputs.

That previous list, however, wasn't a particularly likely combination of equipment for a site. I didn't list a DC plant, for example.

Next, let's look at a telecom-hut equipment list that you might actually encounter in the real world.

Here's what a typical ISP hut might contain:

  • HVAC: (2x) Marvair AVPA60ACA (6-ton, 2-stage)
  • Generator: 35kW (+/-) Cummins / Generac natural gas generator with ATS
  • DC Plant: Benning / Eltek -48VDC 15kVA rectifier with 7 battery trays, with four 12V 100Ah batteries per tray (DC power supply)
  • PQM: EnerSure Enkapsis power quality meter (captures input power metrics)
  • Building Automation System: Siemens S7-1200 PLC controller interfaces with ATS, HVAC, and environmental sensors

If you have a larger hut, it might have a somewhat different (larger) setup:

  • HVAC: (4x) Marvair COMPACII HVESA60ACA050 5-ton 2-stage unit
  • Genset: Cummins C80 N6 80kW natural gas generator (or equivalent Generac generator) with ATS (Kohler Power KSS-AFNA-0400S)
  • PQM: EnerSure Enkapsis power quality meter (captures input power metrics)
  • DC Plant: Eltek Flatpack2 SP2 Trilogy -48VDC 600A rectifier (or equivalent Newmar) with 8x trays of 4x 12V 100Ah batteries ea.
  • Building Automation System: Siemens S7-1200 PLC controller interfaces with ATS, HVAC and environmental sensors

Whatever your equipment happens to be, list it! Then, look at user manuals (or the actual devices) to determine what outputs are available for alarm data.

Step 2: Create Your Short List of RTU Models

There are a lot of RTU manufacturers out there. Each one produces at least a few different models to cover different site sizes.

Start by reviewing websites and "glossies" (spec sheets) to find out which alarm monitoring devices have sufficient inputs to cover your list of equipment.

The specifications section of a NetGuardian brochure
Use printed specifications like the ones shown above (from a NetGuardian RTU) to narrow down your purchase options.

If you have telecom huts that vary significantly in size, you might need to execute this process a few times.

Don't get carried away, though. Standardization counts for a lot. It's better to waste a decent amount of excess capacity than to have 20 different RTUs to support internally.

Also, you need to filter your options by:

  • RTU output protocol and channel:
    Are you reporting via wired LAN, cellular, or satellite? Do you need to send SNMP to your SNMP manager, send emails to your technicians, or something else?
  • RTU form factor:
    Are you mounting in a 19"/23" rack? On a DIN rail? On the wall?
  • RTU durability rating:
    Is your telecom hut climate controlled? Most are, thanks to the generated heat load. Still, consider whether you'd like an industrial-rated RTU that will almost always be the last piece of equipment to fail during a disaster scenario. Good monitoring data during a crisis like that is absolutely critical.

When you have a short list of perhaps 3-5 RTUs that will cover your telecom hut alarms, it's time to make first contact with each manufacturer.

Step 3: Ask Tough Questions about Your RTU Manufacturers

Now, things get interesting.

You have a list of a handful of RTU models in front of you that, on paper, look like they will deliver effective remote monitoring of your telecom huts.

But who is standing behind the product?

In particular, you should be asking:

  1. Are you actually the manufacturer, or are you just a reseller?
  2. Do you build your RTUs in-house, or does someone else do it? Where?
  3. How long have you been making this type of equipment? (age = battle scars = better decisions = better reliability)
  4. What tests do you perform during engineering? What tests do you perform during routine production? (EMI, power cycling, hardware verification, etc.)
  5. Can you give me a list of references from my industry of your customers who can vouch for you?
  6. What is your oldest installed RTU that is still being used today? (this question reveals equipment reliability and long-term design focus)

Your Telecom Huts Need to Be Monitored. It's Up to You. DPS Can Help.

Choosing an RTU is a little bit tricky, but there's really not that much to it.

Fortunately for me, I go through this process multiple times a day as I talk to new DPS clients.

Unfortunately for you, you probably haven't had to buy an RTU recently. If you've ever done it before, you probably (hopefully!) didn't need to do it again during the next 5-10 years.

Follow the steps I outlined above to get started. If you'd like help at any point, I'm here to help. If I'm already on the phone or traveling to visit a client, the entire DPS sales and engineering teams (just ask for Tech Support) are here to help you.

Call us at 559-454-1600 or sales@dpstele.com now.

Andrew Erickson

Andrew Erickson

Andrew Erickson is an Application Engineer at DPS Telecom, a manufacturer of semi-custom remote alarm monitoring systems based in Fresno, California. Andrew brings more than 17 years of experience building site monitoring solutions, developing intuitive user interfaces and documentation, and opt...