This forum is for discussions regarding System Infrastructure and Related Equipment. This includes but is not limited to repeaters, base stations, consoles, voters, Voice over IP, system design and implementation, and other related topics.
What is the Batlab wisdom around portable generators (Honda Gasoline, or some small diesel DC generators) that can be used on roof top sites to keep your equipment going through a blackout?
I have many sites that have critical transport facilities (microwave, or fibre) on roof tops in urban areas. Eight hours of battery is standard. Some have connections to building Safety of Life emergency power, but this isn't available everywhere. Often Natural Gas is on the roof for boilers, so there is potential for a new resident generator. But some sites still fall through the cracks with no viable options or an expensive, unwilling landlord.
So I've been looking into the fire codes around storing and transporting fuel to the roof (gerry cans, what else!) or running a 5 kW Honda. Some vendors also offer portable diesel or DC output. Simplistically, so far it looks like gasoline is a no-no, especially for the elevator. Diesel is less volatile... and has a better shelf life.
What are you doing and what fire or other code considerations have you made? Thanks for your insight.
How much stuff do you have to run? A 5kw set will be a bear to pack up there.
Several years ago, I used a "Homelite" (actually Yamaha) that also had about 8 A DC output available to charge batteries. FWIW, no one ever questioned me about taking it to a rooftop via elevator, stairs or once even pulling it up on a handline. I kept the little generator and a plastic 2 gallon gas can in a (vented) compartment on my truck. Every month or so I would dump the can in my truck's tank and refill. I'm not a fireman, so I cannot address the "code" issue.
Where I live, which is DC, the FD and Bldgs. Dept. will not allow gasoline-powered permanent gensets. They must be either Diesel or natural gas. Storing gasoline makes everyone nervous, hence the requirement, which to me is pretty obvious. The trade off on the natural gas is that the efficiency drops by about 15%. The upside is that you have no storage problems and the fuel is always there, fresh, waiting to be used. When I was selling these things some years ago we didn't sell many gasoline units compared to Diesel, and in DC the users most times opted for Diesel over natural gas for some reason or other, so go figure. The biggest problem with emergency generators in buildings is getting the staff to maintain them properly, automatic exercisers notwithstanding. When the set fails to start when needed the building manager wil always swear up and down that he ran it himself "just last week," but when it's investigated it becomes obvious that the damned thing has not been run in several months. Good old cockpit problem, as usual.
Tom in D.C. In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
RFdude wrote:What is the Batlab wisdom around portable generators (Honda Gasoline, or some small diesel DC generators) that can be used on roof top sites to keep your equipment going through a blackout?
I have many sites that have critical transport facilities (microwave, or fibre) on roof tops
If "X"hours of battery is not enough, in a prolonged blackout (nee NYC last summer), do you have enough staff to get around to the sites during a blackout to deploy & refuel the gensets?
If the circuit is truly mission critical, it needs a permantly installed genset or enough battery (N+1) to get by until a tech gets there.
The other issue would the building occupants "borrow" a portable DC unit during a blackout or other disaster if left unattended? Not that DC would help them run their bigscreen TV anyway.
Tom in D.C. wrote:Where I live, which is DC, the FD and Bldgs. Dept. will not allow gasoline-powered permanent gensets. They must be either Diesel or natural gas. Storing gasoline makes everyone nervous, hence the requirement, which to me is pretty obvious. The trade off on the natural gas is that the efficiency drops by about 15%. The upside is that you have no storage problems and the fuel is always there, fresh, waiting to be used. When I was selling these things some years ago we didn't sell many gasoline units compared to Diesel, and in DC the users most times opted for Diesel over natural gas for some reason or other, so go figure. The biggest problem with emergency generators in buildings is getting the staff to maintain them properly, automatic exercisers notwithstanding. When the set fails to start when needed the building manager wil always swear up and down that he ran it himself "just last week," but when it's investigated it becomes obvious that the damned thing has not been run in several months. Good old cockpit problem, as usual.
One issue with Natural Gas is that it is not acceptable as a sole fuel source for life safety generators - Hospitals, public safety, etc. I guess the justification is that if the power goes out, eventually you'll lose gas service. Propane is OK.
The DC versions seem most useful. They put out 60 to 100A depending on engine output. No need for a transfer switch, and they can shut off on their own when the power returns and the battery voltage is back up. Of course, having DC ventilation is another story.
One building in particular is interesting... we are up about 22 floors. No Natural Gas in the building. And the diesel room is in P1 and on the opposite side of the complex. Add it all up, to put a diesel in and conduit would be very, very expensive. In many cases, a 5 kW DC gen on the roof would keep the microwave and PCS going indefinitely. And the little 11 HP engine uses half gallon/hour, so a small tank can go days. But think of a big cellular outfit...who will hand balm the fuel up there... will the fire codes allow it (storage and transport)... its not a traditional solution, etc... My biggest issue is keeping people's minds open to the idea. Many would rather spend $100k for the elaborate solution than $12k for the small solution.
Hence I'm looking to the batboard to see if this idea can practically sink or swim!
Having spent the last 2 years installing generators for cell site backups, I would add my 2 cents here. Roof tops are a royal pain in the lower posteria. Many landlords will let you put a generator up on the roof until they hear it run for the first time. Then anyone below it complains about all the noise and vibration it puts into the building. Next thing you get a call to remove the generator from the roof.
Most of the cellular people have taken the stand to try and place the generator down at ground level and run the power up to the roof. This solves the fuel problem, weight limit on the roof, vibration noise and the engine noise.
Put the ATS where ever it needs to be and run the AC output from the generator to it. You will need 2 conduit runs. One for the AC output and the other for the control. Don't forget the battery charger needs AC power to keep the battery up. This feed can be obtained near the generator.
By the way, I haven't found any fire marshal that will allow gasoline to be stored on the roof of a building. The amount of diesel is limited as well as the amount of propane. Each area has it's own regs to cover this issue. Some building owners won't allow you to put Natural gas out on their roof.
Jim202 wrote:Having spent the last 2 years installing generators for cell site backups, I would add my 2 cents here. Roof tops are a royal pain in the lower posteria. Many landlords will let you put a generator up on the roof until they hear it run for the first time. Then anyone below it complains about all the noise and vibration it puts into the building. Next thing you get a call to remove the generator from the roof.
To add to what Jim mentioned, a fuel cell might be an option. Proton exchange membrane units (PEM) can produce 48VDC for common carrier and can be optioned for 24VDC for microwave and repeaters.
Still will need CNG or propane, but there's no vibration from the PEM cell itself. (other then fans)
We have multible sites with propane generators. Where we have roof top installations, all generators are on first floor or under ground.
We do have a few Honda 3K generators, that we use for emergensies. The good thing about them are they are very quiet (dont wake up the neighbors at ex firestations) and they can be hooked up together, if we need more power. We need them, because we are depend on PGE and another agency for maintenance of the generators(yeah I know all goverment jokes).
Keep the comments coming. This is good information from the BTDT side. I've done dozens of Diesels in ground shelters, but the building issue is new.
I'm not concerned about storing fuel since the area isn't seismically active, so regular NG is OK. The pipelines are self-sufficient for blackouts.
Most of the roof tops here do have NG for hot water boilers. Seems pretty easy to install a roof top machine. I've asked for additional vibration dampening... so the machine skid gets mounted on the dampeners and then on a metal frame to the building concrete. We will minimizing exercise to once per month to try and keep it low key. The machines are in 68 dB(A) enclosures.
But we haven't completed any yet... I've got about 45 buildings to do in all and will have the first few ready soon.
In the past, I've connected to the building emergency generator where possible, but we tend to avoid this one unless there is a lot of spare capacity.
So your advice to give up on the roof is probably wise. Jim, if I read you correctly, seems you have tried but had your share of issues.... never to get it good enough to keep the complaints down. That expensive fuel cell solution is starting to look better.... $$$$.
I've found a number of small scale solutions... like the DC generators I've mentioned or small 11 kW NG units. Considering how few hours we do put upon generators, the price is a fraction of the traditional 40 kW approach. But you can't run the HVAC....
I hear Nextel just awarded Kohler a generator contract....for about 150 units in the next year. In all, my project is about half that size.
[quote="RFdude"]Keep the comments coming. This is good information from the BTDT side. I've done dozens of Diesels in ground shelters, but the building issue is new.
I'll stick my neck way out and pass a few comments that most people are not aware of. Make sure that when your purchasing a generator, that spare parts and common items like oil filters, fuel filters, starter motors, radiator hoses are all obtainable at the local auto parts store. There are a couple of generator companies out there that have sole source provider for their parts.
There is no way that I would be held hostage to one company and have to pay over $600 for a starter motor that is made in Japan. The radiator hoses are special made and you run into the same problem. If you look real close at the radiator, you will see special caps covering unused hose ports on the bottom. These have to be replace about every 3 or 4 years. They use cheap ass relays that the weather gets to and the engine won't start.
Make sure that you ask for a list of a number of users of the generator your thinking of buying. Call those companies and ask to talk with the person responsible for the maintenance of those generators. Ask detailed questions on how the generators have been over the last couple of years.
The first year is no big deal. It's the 3rd year and beyond that your reliability start to show up. I have been through just about all brands of generators over the years. The list of them in no special order is:
Katolight, Kohler, Onan, Lynx, Yamaha, Generac, Cat and a number of others that have long since faded from my mind. A few of these are real good, one is in the catagory of I won't touch it. The rest fall somewhere in between.
Bear in mind that the most of the emergency generators for com sites seem to fall into the 25 to about 60 KW range, with 30 or 40 KW the most common. You also have the mechanical and electric governor. Each has good and bad features. Kind of depends on the application on which one you go for.
I could write a book on this subject. But enough for now.
I have to agree with you on that one, every G*n*r*c set I have worked with has been in that catagory. I especially hated the big block Chevy powered unit they made that had the radiator core cut out and the drive coupling thru there. Then there was the gear drive they had that ran the engine at about 2500 rpm and the alternator at 3600. Never again if I have any say in the matter.
[quote="mastr"][quote]one is in the catagory of I won't touch it.[/quote]
I have to agree with you on that one, every G*n*r*c set I have worked with has been in that catagory. I especially hated the big block Chevy powered unit they made that had the radiator core cut out and the drive coupling thru there. Then there was the gear drive they had that ran the engine at about 2500 rpm and the alternator at 3600. Never again if I have any say in the matter.[/quote]
I have worked on one of those. It was spec'd for the generator to run at 1800 RPM.. They slipped it to the owner and ran the engine much higher through a gear box to get enough power to generate the required 100 KW using Natural gas.
The fan belt sliped one day that drove the radiator fan. The result was a shattered fan and a generator that was unavailable for about 2 weeks. Takes a great brain dead engineer to run the fan shaft through the radiator and have the fan on the wrong side of the radiator from the engine. Also makes more noise.
That is the one I mean, I guessed that the alternator was a 2 pole, given the overall engineering of the rest of the set. To be honest, I didn't want to know much about the thing.
I was just thinking of that POS today, I am "signing off" on the installation of a 4bta powered Onan (80kw) Friday AM, the initial test run was slightly over 1MWhr over about 36hours. It is a nice set, but the electronic controller will probably keep me up at night during thunderstorm season. Maybe we can spring for a complete spare board.
And unless you regularly run the gasoline engine to get rid of old gas in the tank, line, carb etc. the old gas will go "bad" and clog up carb jets and leave a nasty residue. Gasoline starts getting "old" after a few months. Additives can be used to extend this life. I haven't tried them yet. During the last hurricane when we placed gasoline generators at repeater sites other users plugged into our generators without asking. Another reason for placing generators on a lower level is for ease of connecting to the main power panel through a transfer switch for automatic stand-by operation.
