When building smart grid solutions, the focus is always on the smart meters and the smart grid feeder technology, as well as the ever important communication networks, which is correct. However, it always amazes me how much the supporting infrastructure is ignored or forgotten. The supporting infrastructure is vital as it underpins the core infrastructure. So, neglecting the supporting infrastructure is madness and leads to appreciably higher OpEx costs and extended outage periods for the core infrastructure due to supporting infrastructure challenges. In this article, we will consider the importance of the shelter (sometimes called a communications hut). The innocuous shelter holds the core infrastructure and protects it in many ways. Getting the technical details right from the outset will provide a shelter that will perform for decades without fail. Here are some of the issues that need to be considered regarding the shelter.
The single biggest mistake is not sizing the space necessary for the smart grid infrastructure. Too often we see shelters that are undersized and are not even capable of supporting the base requirements let alone any future requirements. Trust me when I say, there will always be future requirements! So, over sizing the shelter is smart. Super sizing it may be wasteful so finding the right balance is critical. Shelters need to be transported to the site, therefore road access considerations play a big part in the size of the shelter. Some shelter are positioned at places where road access is not available, so on-site assembly or slinging the pieces in by helicopter have been done. Those of you with communication needs in remote or mountainous areas have undoubtedly faced this difficulty. So, how big is big enough? Shelters come in a myriad of sizes. Modular shelters that permit future expansion are becoming popular too. We have seen whole data centres created in modular shelters, typically at mine and carrier sites. So, the electrical industry can borrow this strategy if warranted.
Common shelter sizes are: 8′ x 10′, 10′ x 12′, 10′ x 16′, 12′ x 20′, 12′ x 24′ and 12′ x 30′. So, rectangular shapes are the norm. Shelters can be stacked vertically if space is limited. A horizontal layout of several shelters is growing in popularity too.
A typical smart grid shelter size is 10′ x 12′. Placement of the door, HVAC units, power panel, and other supporting devices needs to be planned carefully to make small spaces work. The layout of the equipment racks, cable entry ports, and overhead ladder cable tray with consideration for optimized space use while respecting fire regulations for access space and emergency egress needs is mandatory.
Once you determine that you need a shelter, the next question is to decide where to place it. There are many issues to consider.
The first goal is to get the shelter as close to the antennas as possible in order to minimize cable runs lengths. However, in northern locations and regions where ice forms, this can place the shelter in the direct aim of falling ice shards which can slice a shelter to pieces. Protection of the shelter, cable pathways, and of course, the workers from falling ice is paramount.
The second issue is interference. RFI and EMI issues may affect the wiring, grounding, and equipment. Exposure to prolonged ionizing and non-ionizing radiation is a serious issue for workers too. Great care must be taken with radiation.
Third is access to the site. Being able to access the shelter is critical too. I have seen beautiful shelters that take hours to get into due to the need for snow shovelling, so think of the weather and how the workers will get to the site. Are the roads accessible? Is the property accessible? Can security gates be opened in deep snow?
Fourth is safety. What about danger from wild animals – bears, wolves, snakes, etc. At some sites, the workers need to carry rifles, so are they trained and qualified to use these weapons to protect themselves? Due to remoteness, some shelters have sleeping accommodations and short-term provisions such as water and dried food. In urban and suburban areas, access can be equally challenging, obviously not from wild animals, but from an access perspective, are the roads blocked or have cars been parked in front of the gates? Is the neighbourhood safe at night?
Depending upon the soils, the type of foundation used for the shelter to sit upon may vary by location. Normally, we use concrete formed as caissons, slab / mass, footings, a combination of caisson / slab, or rock anchors to secure the shelter. Other approaches are used in unique situations, but caissons are the most popular foundation. Caissons can drift so tying them together into one cohesive form is important, sometimes the frame of the shelter can do this task on smaller shelters, but for larger shelters it is important to bond them into one structure.
Having geotechnical or soils analysis in advance of designing the foundation is vital to ensuring that the right foundation is built and it is able to support the loads of the shelter. In northern climates, the frost line must be considered as the foundation needs to be set well below the worse case depth of frost in order to guarantee a stable foundation.
In the image of the shelter above, it is raised high above grade to protect the equipment from ocean surge and waves as the grade is just one feet above sea level.
Shelters can be made from a variety of materials. Common materials are steel, concrete, wood, and aluminum. The weight of the materials impacts the method and resources used for delivery of the shelter to the site as they are normally built off-site and shipped in whole or in large pieces. Normally, the shelter is simple placed onto the foundation and then secured into place. Telephone, optical fibre, power and grounding are added once the shelter is secured.
The foundation is built in advance of the delivery and then a crane or a HIAB crane is used to position the shelter on the foundation. In some cases, an all-terrain crane is needed to set the shelter on the foundation. Flatbed trucks are used to delivery the shelter. It is important to determine access on all three dimension including turning radius for the trucks before deciding how to get the shelter delivered and installed. Articulated trucks with short trailers are useful for delivery in tight confines. Do not forget about the height of the shelter on the trailer as you will need to clear tree branches.
Water run-off and drainage from rainfall and melting snow is important so constructing ditches and swails is often necessary for the site landscaping. While trees can cause signal blockage, some trees can be useful to protect shelters and block wind. It is not unusual to select specific trees and shrubs for landscaping that are RF friendly. Mulberry trees are used as they provide good density and do not grow too tall.
Storing diesel fuel for the generator can be tricky under current legislation so specialized storage tanks within catchment basins are commonly requested to contain spills and protect the environment.
Environmental approval processes can be rigorous and may take 6 to 12 months to process. So, installing at a grandfathered existing tower site is often prudent compared to building a new site.
Heating, Ventilation, and Air Conditioning (HVAC)
A stabilized environment inside the shelter is key and extends operational life of the smart grid technology. Factors include heating, cooling, humidity levels and air quality. Specialized HVAC units are available to mount on the exterior side-wall of a shelter. These units are normally provided as fully redundant and are remotely monitored for alarms and failures. Back up fans that can automatically start and stop based upon prescribed conditions are often provided with the shelter from the manufacturer. Annual preventive maintenance is performed on these units to ensure uptime and to clean airflow filters. Sizing of the HVAC units can be done with some simple calculations. I have created my own spreadsheet to define the size of the HVAC units. It is available to anyone who asks.
AC Power and Back-up Emergency Power
AC Power, which is normally set 30 amps / 3-Phase / 208 Volts and 15 amps / 1-phase / 110 Volts for North America is what we might expect to see from the breaker panel within the shelter. The power drop will be a 100 amp, 200 amp or even a 400 amp supply. Other power requirements are required in other parts of the world, especially if 50 Hz is used and depending upon the loads. Regardless of the local power standards, there are normally three or four grounding requirements that must be considered for the system: Lightning Ground, Outdoor Ground, Building Ground, and Isolated Technical Ground.
Installing a generator and a UPS is considered standard these days. Back-up power is critical when the smart grid must operate at five or six nines of availability. In some locations we are seeing renewable energy installed, mostly solar panels to keep the batteries fresh and recharged. With the advent of new energy storage technologies from companies like Tesla, Siemens, and GE, we expect to see them installed with shelters to augment solar panels and to compliment UPS and generators.
Lighting comes in several forms. Lighting inside the shelter is for general room lighting and for a more enhanced level for working at the rear of the racks. It is usual to have this lighting installed by the shelter manufacturer before delivery to the site. Other types of lighting include outdoor lighting for site illumination aimed at safety and emergency alert lighting to notify workers of situational status, such as the firing of the fire suppression system.
At larger shelters, and when insurance demands it, fire suppression systems are installed to quench a fire immediately upon detection. Gone are the days of halon and carbon tetrachloride. It was found that halon and carbon tetrachloride could lead to severe health effects as well as severely impact the deplete the Ozone Layer. Today, we use many solutions, over a dozen options exist, from FM-200 (Heptafluoropropane) (see image below of a bottle system for shelters), to 3M’s Novec 1230 (Fluorinated Ketone), to water mist, and water. Some of the newer solutions can cause damage to the electronic systems they are protecting but provide a clean, safe solution to suppress the more dangerous fire, especially in forest areas where communication towers are often located.
Utilities build some wonderful shelters and then neglect to use a site monitoring system to watch over the various systems and remote the status to an alarm monitoring service or to the Utility NOC (network operations centre). Site monitoring can report: alarm triggers, operational value changes, system failures, break and entry, fires, power failures, and more. They often just use a simple telephone line or a cellular modem to connect. In other cases, when the site has a broadband connection, they can leverage it to alert of any situation that warrants attention. It is not unusual to have sensors in the fuel supply tank and alert when a new fuel delivery is required. Remote testing and exercising of the UPS and generator are often preprogrammed to have once per week.
Fencing and Physical Security
Any site that falls under the NERC regulations requires adequate fencing to protect the parameter from unauthorized intruders. They sites are typically unmanned so proper security in the form of fences, razor wire, gates, locks, access card readers, video cameras, video recorders, proper signage and lighting all contribute to a more secure site. Most site security systems need to be monitored and controlled. Prior access approval is often required before a site can be visited and entered.
The #1 reason for a failure in the field is poor installations by unqualified technicians implementing the systems. Wiring the systems needs to be performed by professionals who understand the technology that they are connecting and the environment that it will operate in. Many shelters are located in challenging environments. Installation supervision of the installation should be deemed mandatory. A quality control check process with adequate documentation and reviews should also be mandatory.
There is an old adage regarding installation work, it is called the “Ten-One Hundred One Thousand Rule – It cost $10 to do it right upfront, $100 to fix it during implementation, and $1,000 to correct a deficiency after installation is completed. So, remember, the quality of the craft skills is one of the lower cost aspects that can yield the greatest gain in long-term performance of the smart grid systems.
Truck rolls are the most costly aspect of operating a network. So, a Utility can eliminate or reduce the costs associated with expensive truck rolls by taking some care upfront.
Using a fully qualified team of Professionals to support your project may seem to be expensive but in reality it truly saves money over time with well planned, well designed superior installations. Examples of the professionals that you may need on your shelter project include: Architect, structural engineer, geotechnical engineer, lawyer, insurance and bonding professional, construction management, mechanical engineer, electrical engineer and electrician, and project manager.
Some of these professional services can be bundled in from the shelter provider or your preferred systems integrator. Others might be combined from the professional services provider that may offer architecture, property engineering, structural engineering, and more under one roof. Still other of these professional services may come from the systems integrator or from internal staff.
Here is a list of other issues that are needed for every shelter project too, so do not forget them.
- Liability insurance
- Workman’s compensation insurance
- Errors and Omission insurance
- Performance bonds
- Non Disclosure Agreements
- Site access security
- Pre-build off-site location
- Safety clothing – hard hats, boots, glasses, high visibility vests, radiation detectors, etc.
- Safety suits for some substations
- Specialized site training – substations
- Always check references, at least 3 to 5 as a minimum if you have no experience with the sub trade
- Financial and credit checks
- Payment schedule, have it all agreed to in advance
- Quality control standards and reporting
- Weekly project meetings – most important issue that often is forgotten or disregarded. These meetings need to be mandatory for all hands, with minutes and a strong project manager driving the project towards completion
Shelters are a critical piece of every smart grid. Whether they are installed in a remote, rural, suburban or urban location, on the ground or on a high rise rooftop, equal care needs to be taken to ensure that this fundamental criteria for project success is properly addressed. If you want to save money over the lifespan of the project, provide a safe, trusted and reliable smart grid solution, then do not neglect the shelter requirements.
Michael Martin has more than 35 years of experience in broadband networks, optical fibre, wireless and digital communications technologies. He is a Senior Executive Consultant with IBM’s Global Center of Excellence for Energy and Utilities. He was previously a founding partner and President of MICAN Communications and earlier was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation. He holds three Masters level degrees, in business (MBA), communication (MA), and education (MEd). As well, he has diplomas and certifications in business, computer programming, internetworking, project management, media, photography, and communication technology.