Feel the Power
Jul 1, 2008 12:00 PM, By Doug Irwin, CPBE AMD
There are so many items in a radio or TV facility that we classify as mission-critical; but what can possibly be more mission-critical than the station's power source? Living in a large metropolitan area � such as I do � one of the worrisome aspects of summertime is the possibility of rolling power blackouts. And that's just one reason for the power to go off.
Precipitated by the Clear Air Act, in 1979 the EPA advanced new source performance standards from stationary sources, which includes ac power generation equipment. New standards were developed (known as Tiers 1, 2, 3 and 4) but it wasn't until 2006 that the final regulations were set in stone. In the interim period, different states developed different standards. Today the EPA requirements in Tiers 1 through 4 are the minimums that any particular state must meet (see CFR 40 part 60). Tier 1 regulations were phased in from 1996 to 2000; Tier 2, from 2001 to 2006; Tier 3, from 2006 �til 2008; and finally Tier 4 from 2008 through 2015. The purpose of the tiers is to diminish over time the release of particulate matter (PM) and NOx (nitrogen oxides) into the atmosphere. In 1998 the EPA estimated that by 2010 NOx emissions would be reduced by about a million tons per year � the equivalent of taking 35 million passenger cars off of the road.
A new model for power
Buying a new generator today means that you'll be getting more than just an old, smelly beast that sits out behind the transmitter building, practically out of site and all too often out of mind. Aside from running cleaner, many come with modern communications facilities that can make our lives as radio engineers a little easier. For instance, Kohler makes an extensive line of generator sets, over a very wide range of power and different fuel systems, such as diesel and LPG/natural gas. A recent addition is the Powerscan Monitor System, a monitoring and alarm system that communicates outbound via the GSM cellular system. User-defined alarm conditions and telemetry are forwarded to a control center via the wireless connection, and thereafter forwarded for action to whomever is designated by the generator owner. Messages can be sent by e-mail, telephone, fax or to a pager. A website is maintained at the control center as well, allowing the end-user to remotely monitor the generator.
Temporary power systems are ideal in a crisis, but permanent systems are a better solution.
Not to be outdone, Cummins/Onan offers a wide range of power levels as well, with the typical fuels: diesel, LPG/natural gas and gasoline. Its monitoring and communications system is known as Power Command Iwatch and is a browser-based system that allows the generator set to be operated and monitored via LAN/WAN or the Internet (or even a good old-fashioned telephone line modem). Start/stop capability in addition to telemetry is available via what Cummins calls an easy-to-grasp GUI. Alarm conditions are reported to the end-users of the genset by way of e-mails.
Cummins is also working on a commercially-viable SOFC (solid oxide fuel cell) in conjunction with the Department of Energy. The power level is 10kW, and its introduction to the market is expected no later than 2011. Natural gas is the fuel source for the SOFC, by the way. The goal for the cost of the system is $400/kW.
Caterpillar is a familiar large manufacturer of generator sets powered by diesel or natural gas. Probably the most interesting aspect of Caterpillar is the maximum sizes that it builds � over 10MW for diesel and about 5MW for natural gas.
Generac is yet another familiar generator manufacturer. In addition to its line of compression-type engines (i.e., those running on diesel fuel) and spark-ignition types (gas) it also offers a Bi-Fuel system, which is actually a redundant fuel system. When the generator starts, it runs on diesel; but as the load is applied, natural gas is substituted. Just enough diesel is left in the mix so that the compression inside the cylinders will continue to ignite the fuel mix. The primary advantage asserted by Generac to a system such as this is the greatly extended run time due to a reduced draw on the diesel fuel itself. Should the source of natural gas be missing for some reason, the generator will run 100 percent on diesel.
If you can't be satisfied with just a single generator for standby power at your facility, you may want to consider multiple units, with their outputs combined via large switching panels and synchronization of the output waveforms. All the manufacturers I've mentioned � Cat, Generac, Cummins and Kohler makes systems to accomplish that.
Having a generator is one step. It's also important to maintain backup systems for peak operation.
It's obvious in this day and age � with a radio or TV facility almost completely reliant upon computers for the generation of program material � that keeping the power available during the time it takes to switch over to the standby power source after a power failure is an absolute necessity. That's where the UPS comes into the picture. For our purposes there are basically two types of UPSs: off-line and online (commonly known as double-conversion).
If you are planning on backing up ac power that feeds computers, avoid the off-line UPS types. The problem with that type is that it needs time to not only detect a loss of ac, but to switch over to its internal backup source. This series of events is going to take around 20 milliseconds; during that time the power supplies that feed the computers, routers and all other equipment are going to have to use their internally stored energy (in those big power supply capacitors) to make up the difference, and when that happens all kinds of havoc can occur.
So, assuming you are settling on the online type, you then must decide to what level you want your system backed up. Will you protect individual racks that hold important servers, for example? Or will you provide a backup for your entire technical core? There are many factors to be considered in that decision, but I do want to bring to your attention some manufacturers and what they offer.
Feel the Power
Jul 1, 2008 12:00 PM, By Doug Irwin, CPBE AMD
Generators are available in sizes ranging beyond 10MW.
APC offers an extensive line of UPS units including the Smart-UPS RT. This series of on-line UPSs comes in power levels from 1 to 10kVA. The 10kVA unit uses 10RU of rack space, weighs 440 lbs, and has a half-load run time of 13 minutes. Serial and Ethernet communications are standard. (Just think about all the e-mails you're going to get when the power goes out!)
One manufacturer you may not have heard of is Falcon Electric. I'd like to point out its SG series of online UPS units, in the power range of 800VA to 6kVA. Falcon also points to another advantage of online UPS technology � the elimination of UPS problems associated with drifting frequencies, as well as voltage, in the output of a generator.
In the design of a new facility, if you decide to provide UPS backup for the entire technical core (or maybe even more) you could easily go with a large UPS that makes use of batteries for energy storage, such as the Tripp Lite Smart Online SU80K modular UPS system that provides 120/208Vac three-phase outputs. It's an online system with all the advantages I've previously described � but it's made up of four separate 20kVA UPSs, which according to Tripp Lite gives the end-user the capability of working on the system even while the load is energized. I should also mention it includes a manual bypass breaker and an automatic bypass function.
There is yet another option for the on-line UPS backup for the technical core � one that uses energy stored in a rotating flywheel as opposed to backup batteries. Active Power offers Clean Source in a wide power range, from 130kVA up to 3600kVA. It's highly efficient � up to 98 percent in fact � and though you won't have to maintain or dispose of large batteries you will need to change bearings for the flywheel upon occasion. I must also mention the application (aside from full-time line power conditioning) is to bridge the gap between the time the utility power goes down and your generator starts. This type of UPS isn't meant to supply an entire facility for a substantial amount of time.
Perhaps you are not in the market for a new generator or UPS, but instead are interested in alternative power sources for your station's studio or transmitter facilities. There are at least two different technologies readily available and warrant your consideration.
KGO has installed a solar panel system to supplement its real-time power needs.
It's interesting to note that most energy sources on the earth are in reality derived directly from the sun � whether it is electricity from photovoltaic cells, wind, fossil-fuel or even hydropower. The ideas aren't new but in many cases the specific technology is. When you stand in the sunlight on a hot summer day, it's a little hard to believe that a burning ball of gas 93,000,000 miles away still feels that hot! Indeed, the amount of energy from the sun intercepted by just the Earth's surface is about 7,000 times more than the total global energy consumption (for 2005 anyway).
Going green is, at the very least, a good marketing avenue for radio. Using alternative energy sources, for even a part of a station's energy needs, is relatively easy to do. Let's take a look at a prime example: KGO radio in San Francisco.
The solar power project for KGO is being conducted at the KGO transmitter site near the Dumbarton Bridge in Newark, CA. A major highway is immediately adjacent to the site (in fact the KGO transmitter is commonly known as �the Towers� in traffic reports) and so it provides a lot of exposure to thousands of commuter eyes every weekday. Its first solar power system is made up of photovoltaic cells (PV) manufactured by General Electric and mounted in flat arrays on the roof of the transmitter building and near it on the ground. Its second solar power system is based on the use of concentrator photovoltaics (CPV) and is provided by Solfocus of Mountain View, CA. The CPV system is really quite simple and elegant. Small mirror arrays (main and secondary reflectors � simply a small version of a satellite dish) collect sunlight with a gain of about 500 times. The collected sunlight is then shined on a small PV cell, with efficiency nearly three times that of a standard PV. The CPV cells are mounted in flat-panel arrays that track the sun along azimuth and elevation.
In the case of KGO, this CPV solar system operates in real time, without battery storage. Energy collected from the sun is converted to 60Hz ac, and added to the feed from the local power company, Pacific Gas and Electric. KGO Director of Engineering Joe Talbot expects the peak output from the CPV system to account for about 10 percent of the total needs for the KGO transmitter facility (it is a 50kW site). Talbot also indicates that about half the capital expense of $200,000 will be covered by incentives provided by the state of California in conjunction with PG&E.
The answer is in the wind
If you want to go beyond what KGO is doing and generate power by way of the sun and wind, you can meet (at least part of) your site's needs through the entire day. In theory you could generate power from both the sun and the wind during the day, store some of it in batteries, and perhaps rely upon the wind generator by itself at night. Let's take a look at one station that is generating a substantial part of its needs by way of the wind.
The Skystream 3.7 is a new generation windmill helping facilities generate substantial power.
KPAN radio, located in Hereford, TX (in the heart of the Texas panhandle), uses a small wind turbine (the Skystream 3.7) from Southwest Wind Power of Flagstaff, AZ. This unit is rated at 2kW of constant output, with a peak capability of 3.4kW. Like the KGO system, the output of the Skystream 3.7 is in the form of ac power that interconnects with the user's utility feed (if it turns out that the Skystream generates more power than is being used, the utility meter goes backward). Chip Formby of KPAN tells me the entire kit costs about $5,600 � and can even be sourced by mail order. (Installation in the case of KPAN was around $10,000.) Sounds easy enough � but you will need about a half acre of land, a 45' pole, and an average wind speed of at least 10mph. Although the system is brand new (about two weeks old as this is composed) Chip expects the system to provide about 25 percent of the energy needs of the studio facility during the windiest months. He also tells me that the Skystream will power the studio facility completely while the studio is unattended.
As an alternative consideration, you may also want to look at Endurance Wind Power. Its small wind turbines make use of an induction motor, with an output that is 60Hz, and connects directly to the power grid without making use of an intermediate dc to ac inverter.
Feel the Power
Jul 1, 2008 12:00 PM, By Doug Irwin, CPBE AMD
Finally I'll mention the fact that there are ways (at least in some states) to make use of wind power right away without building it for yourself. Rocky Mountain Power, which provides power to customers in Utah, Wyoming and Idaho, has a program known as Blue Sky, which allows its customers to purchase power sourced completely from wind energy.
Developing new, standby or alternative power sources for your station gives you an opportunity to exercise your environmental convictions � but it goes farther than that now. Energy prices are increasing � without looking back � and considering ways to break our dependence on the traditional sources of energy makes financial sense even now and probably more so into the future.
Irwin is chief engineer of WKTU, New York