Repeater Site Sanity Check!

[spareparts]

I have been recruited to help with building a repeater site (the while thing, not just the RF stuff). The owners have access to a Kullman modular building (former Verizon cell site) for the shelter. From what I understand, they will be buying a new Rohm tower.

I was roped into doing the power system. They can't afford a standby diesel genset at this time , so here what I propose to do: Install a 100 Amp Square D panel board for the AC side with an Asco transfer switch. On the genset side, I will install a 100 amp pin & sleeve connector for AC input. The will allow power into the shelter during construction as well. This is the setup that was originally installed, but removed by Verizon.

On the DC side, my idea was to make use of the existing trays and racks for a battery string. Is there any RF equipment, other then microwave stuff that needs 24 volt power? I was planning on a 12 volt install, unless there is an reason to go to 24 volt. BTW, the battery string will be Absorbed Glass Mat/Lead Acid type typically used in telco power systems.

Basic sanity check here - I did telco power systems and have the tools for the large diameter cables, so that's not an issue. I just want to do it once and not have to go back up the mountain so to speak to do major surgery. It's going to be a few states away, so that's makes it a bit tougher to do a house call.

[Jim202]

I have been recruited to help with building a repeater site (the while thing, not just the RF stuff). The owners have access to a Kullman modular building (former Verizon cell site) for the shelter. From what I understand, they will be buying a new Rohm tower.

I was roped into doing the power system.

Just what version of the Asco panel are you looking at? the series 165 is not what I would call a good choice for a comm site. It was designed for residential use and has several limitations. One of them is locking up in a can't do anything mode. It has to be manually reset in this case. At times I have had to pull the power connector for about a minute for it to regain it's mind.

The Asco series 300 is a much better choice, but at a higher cost. The series 300 has a much better logic circuit. Itr also has an alarm ability, unlike the 165 series.

As for the Square D power panel, that is a good choice. The only comment I have is about running any Air Conditioning units on them. I have seen 3 ton units eat a panel due to the breakers having loose connections on the power bus. The solution is to spend a little more and go to the bolt on breaker version. This solves the heat problem with loose connections. Think the panel is an SQ series. Ask any good electrician and they will fill you in on this issue.

The shelter will require some regular maintenance. Water intrusion is the big killer of these shelters. Most field techs will not be looking for water leaks. Depending on who made the shelter and how old it is will point you as just where to look.

The most common places for water entry is around the coax entry. Go inside, shut the door and turn off the lights. Look for any light coming from around the coax cable boots and entry hatch. Look for stains on the walls and floor. We use to sprinkle carpenter chalk dust on the hatch plate ledge. Any water leaks would case trails in the chaulk.

Tap the walls to see if they are sound or spongy. Look for the floor tiles coming loose from the floor. Take a broom handle and sound the floor for any stange sounds different from the rest of the shelter. Look hard around the door frame and under the Air Condtioners.

If any power coduits are brought through the walls, look for wall and floor damage around and below them. We changed our shelter design to bring in all conduits through the floor to eliminate this problem.

Look at the caulking on the outside of the shelter. If it is cracked or pulled away, redo it. Look real close to the mounting area around the A/C units. Check for water damage in the on the floor area.

I have been looking at shelters for the last 15 years. Know just about every weak spot in their creation. The fiberglass finished shelters are real bad on these water leak problems. Have seen the floors totally rotted out. Could write a book on what I have seen and found over the years.

I have taken up enough space here.

Jim

[robertisby]

Depnding on the RF Equipment, the battery backup for the highpower motorola stations is now 24 vdc rather than 12 vdc. Look at the specifics for the equipment being installed. Good Luck

[spareparts]

Re the ASCO transfer switch, it is the 300 series, with the alarm option. I have a copper bus QO-B (bolt on) 40 space panel tha I was planning to use.

The shelter is steel frame, poured concrete floor, concrete skin panels, rubber membrane roof. I will pass along the info re the leaks to the owners.

A dual voltage DC power system is not a problem, it's just knowing to add the parts for the second voltage.

Great information - Thanks!

[Jim202]

Re the ASCO transfer switch, it is the 300 series, with the alarm option. I have a copper bus QO-B (bolt on) 40 space panel tha I was planning to use.

The shelter is steel frame, poured concrete floor, concrete skin panels, rubber membrane roof. I will pass along the info re the leaks to the owners. Great information - Thanks!

I didn't mention it directly before, but kind of hinted around the issue. Even though you have concrete on the outside of the walls, most of the shelters have wood for studs and inside panels. Very few have metal studs in the walls. Water leaking into the walls of these shelters is still a concern.

You will like the Asco series 300 ATS unit. That is a fine panel. Just don't let some dumb electrician try to hook up the generator remote start to the terminals on the door circuit board. The start contacts are on the transfer relay assembly itself. I should have a couple of files with all the ATS info around some place. Let me know if you need them.

There are a number of dip switch settings and delays that you have the option of setting on the model 300 ATS. It can be confusing in trying to set the selections.

Did Verizon leave the grounding system in the shelter, or was it all removed? Equipment grounding is just as important an issue as water leaks. There should be a halo ring around the top inside of the shelter and a down wire in each corner going outside of the shelter. All the cable trays, A/C ducts and or grills, door frame and all conduits should be connected to this halo ring.

On the end of the shelter where the power and telephone lines came in, there should be a large ground bar about a foot off the floor. Under each of the cable entry hatch plates, you should also find a large ground bar.

Depending on the age of the shelter will determine just how the ground bars are grounded. There have been a number of changes in the grounding specs. The older shelters will have split bolt connectors used on the larger wire on the halo ground system. On the newer shelters you will probably find that compression crimps were used. In the corners, the halo should have a triangle formed by the down wires going outside the shelter.

All the Neutral wires in the ATS and the power panel should be floating from the cabinet. The neutral wire should only be bonded back at the electrical meter and or the fused disconnect at the meter.

When you do install a generator, make sure they don't ground the Neutral wire in the generator. Many electrical contractors make this common mistake and ground the Neutral inside the generator breaker panel. The NEC says that you can only have one common bond in the distribution system. The normal Asco 300 ATS switches use a common Neutral bus.

You could have an ATS that has a switched Neutral. Then under this condition, you could ground the Neutral in the generator. It wouldn't violate the multiple bonding, as the Neutral would be switched between power sources. I don't care to spend the extra money on the 4 pole switches. It really doesn't do anything for you, except cost more money.

Just remember that the common of the ATS goes to the shelter power panel. Again I have seen some dumb electrical contractors wire them wrong.

Jim

[nmfire10]

Not to change the subject here... But is there a way to get alarm functions out of a Series 300 that doesn't have that option?? We have a Series 300 transfer switch in the firehouse and in the radio tower building but neither have alarm options. I really want to work that into the system if it is possible.

[spareparts]

Matt,
Contact ASCO directly - They sold me a field retroft kit for a 300 series ATS a few years back. Quick & easy install.

WARNING - requires working in close proximity to energized parts.

If you have a back up comms plan, it would be a good thing to test the plan the morning of the day you plan to install the kit, and if it goes well, lock out & tag the power, the generator, & do the install after lunch!

[spareparts]

Jim,
No doubt that this unit is welded steel frame construction. I pulled off an interior plywood panel last night. The panel was glued full lenth to the steel!

The roof is welded steel panels. Visualize a standing seam copper roof & invert the panels so the raised seam is facing down. There is a rubber membrane on top of the steel. From the dents in the steel, it looks like ice falling off the tower did the damage.

The leads for the grounding panels are exothermic welded to the frame, with a 2 bolt Burndy lug at the panel height. Panels themselves are gone.

The halo ground is gone, but I intended to reinstall it. Burndy makes connectors for halo grounds, so it's not a big deal.

I am waiting on word to see if Hendry/Seimens DC rectifiers can live in a high RF enviornment. Otherwise I will use Newmar. BTW, The DC side is being designed for N+1 with a 72 hour holding time.

Martin

[Jim202]

I like the use of double hole lugs in grounding systems. They are hard to knock loose with movement. Many of the cellular carriers now spec them for ALL ground connections.

I need to clarify the statement I made about alarms on Asco ATS units. I guess I have been working too close to them and have started passing along some of the internal comments. By alarms, I meant to indicate that the model 300 ATS units will indicate what position they are in. The option of the remote contacts needs to be installed. The model 300 can also be used to indicate if the generator has been told to start.

On all the generators I ordered, I had alarm relays installed to indicate that the generator was running, that there was a pre alarm and a 3rd to indicate the generator had shut down on an alarm. Both the pre alarm and alarm relays were latched to make them stay on. They also had a number of alarms commoned to them, not just a single generator pre or full alarm.

You can go to the Asco web site and download the info yourself. Site is http://www.asco.com and then select power porducts. Then select the model 300 ATS. There are 2 files in PDF you will be interested in. One is about 1 meg in size for the operators manual. The other is the drawing, about 330 k in size.

Hope this answers your questions and fills in the blank areas.

Jim