POWER LINE NOISE ISSUES WITH GROUND FAULT PROTECTION EQUIPMENT
This type of alarm can be caused by switching high-power loads, inductive loads, or any excessive arcing during operation of a contactor that is on the same circuit branch. It may also be caused by extreme levels of RFI (radio-frequency interference) in the area.
1. USE A SEPARATE CIRCUIT FOR THE HEAT CONTROL
We recommend providing a separate circuit for the heat control, which is not shared with other equipment. In particular, any equipment that is electrically noisy needs to be on a different circuit branch and installed a safe distance away.
2. USE AN EXTERNAL NOISE FILTER
The controller’s immunity to excessive conducted noise from contactors, inductive loads, and other sources of RF interference can be increased with an external noise filter. A simple way to provide additional filtering is to route the power supply cable through a ferrite toroid ring, with as many turns as possible. This will further attenuate the conducted RF noise.
One device that works well is the Palomar Engineering Ferrite Toroid Ring model F240-77. This is 1.4” ID and 2.4” OD, material type 77(Figure 1). There are larger sizes and other suppliers of these which also can work. We purchased our Ferrite Toroid Ring from here, but they can also be purchased at many electronic supply companies or on amazon.com.
This should be installed on the power line (source) cable to the controller (e.g. GPT or FPT), and placed near the controller’s housing (Figure 2). If the controller is fitted with conduit for the wiring to the power panel, the toroid can be placed just inside the power panel, at the end of the conduit (Figure 3). Three turns of the entire cable through the toroid are recommended; if more can be fit that will work better – the attenuation of noise is proportional to the square of the number of turns. A larger toroid can be used to accommodate more turns of the wire.
3. ADJUST THE GROUND FAULT THRESHOLD
In some situations, the ground fault threshold can be increased, and this will improve the noise immunity. On the GPT 130 and GPT 230, the ground-fault alarm current threshold can be adjusted from 1 mA to 300 mA, and the default setting is 30 mA. A higher setting will be more tolerant of electrical noise on the power line.
Please join the ETI Fab team for our Grand Opening & Open House
RSVP with Robin Roberts at:
Friday, September 6th
12:00PM – 4:00PM
17055 Oak Ridge Road
Westfield, IN 46074
Stop by for Food Trucks, Plant Tours & much, much more
ETI FAB PLANT CAPABILITIES
ETI Fab is a world-class metal fabrication facility based in the heart of the midwest in Westfield, Indiana, a suburb just north of Indianapolis.
Welding – MIG & TIG
The eti snow owl
AERIAL SNOW SENSOR FOR SURFACE SNOW & ICE
ETI proudly introduces the ETI SNOW OWL Aerial Snow Sensor for surface snow and ice management systems.
The ETI SNOW OWL is designed to work with a controller or contactor, optimizing energy usage in heated snow/ice melting applications. The ETI SNOW OWL is also an excellent solution for building automation applications.
During dry or warm weather, the system’s heaters are turned off to save energy costs. The heaters are turned on only when snow and/ or ice is present and kept on only long enough to ensure complete melting and drying. Temperature and time parameters can be varied within the ETI SNOW OWL, enhancing system performance in a given environment and application.
To learn more or to order the ETI Snow Owl, contact the ETI Sales Team at: (800) 234-4239
ETI & ETI FAB ARE HIRING
ETI & ETI FAB are equal opportunity employers. We offer competitive wages and great benefits.
THE SNOW OWL
AERIAL GENERAL-PURPOSE SNOW SENSOR
ETI proudly introduces the ETI SNOW OWL Aerial Snow Sensor for surface snow and ice management systems.
The ETI SNOW OWL is designed to work with a controller or contactor, optimizing energy usage in heated snow/ice melting applications. The ETI SNOW OWL is also an excellent solution for building automation applications.
During dry or warm weather, the system’s heaters are turned off to save energy costs. The heaters are turned on only when snow and/ or ice is present, and kept on only long enough to ensure complete melting and drying. Temperature and time parameters can be varied within the ETI SNOW OWL, enhancing system performance in a given environment and application.
- Sleek design eliminates “igloo-ing” effect
- Enhanced UV protection to ensure durability
- Connects easily to 3/4″ PVC conduit
- Handles up to 2 amps on a dry contact & can use AC, FWRAC, DC to serve wide range of electrical and hydronic applications
1850 N Sheridan St • South Bend, IN 46628 • (800) 234-4239
Media Contact: Tim Cramer • email@example.com
FOR IMMEDIATE RELEASE
June 19, 2019
(South Bend, IN) ETI, an OEM manufacturing company that for over 50 years specializes in designing and manufacturing products for effectively managing the environment, announced today that they have completed the acquisition of assets from a global manufacturing company headquartered in Indiana. The acquisition is a carve out of the metal fabrication and machining division located in Indianapolis, Indiana. ETI FAB, Inc is the newly formed entity and has completed the build out of a 30,000 square foot building and is completing the installation of the assets located in Westfield, IN. ETI FAB was able to retain the highly skilled employees and will remain as a leading contract manufacturer of metal and aluminum parts that will serve a variety of industries on a global scale. The facility will manufacture parts to customer designed drawings and produce parts for ETI improving speed in the support of its products. ETI FAB’s services include metal fabrication by laser cutting, forming, bending, stamping, welding and machining.
“Acquiring capability to metal fabricate allows the ETI network to be more insular. This acquisition is our first step in creating our future picture” stated Ben Crawford, President, and CEO of the ETI companies. Crawford further stated, “In working closely with the company that the assets were acquired from, we’re particularly excited about retaining employees that have been operating this equipment for many years. I’m truly grateful for the support and collaboration that has provided a smooth transition to ETI. Their guidance supporting employees and customers is very much admired”.
ETI FAB has begun fulfilling customer orders and will be in full production in June. “The team that has been assembled is a high-performing team that I’m thrilled to lead” stated “Jeff Frazee, Plant Manager of ETI FAB. Frazee further commented, “Our commitment to safety, quality, employees, and customers is our guiding precept”.
ETI, based out of South Bend Indiana, has been a world leader in sensors and controls for snow and ice melt systems, heat trace, and microwave waveguide dehydration for the past 50 years. ETI’s engineering and production teams work with their customers to design and manufacture solutions to their problems with a focus on energy efficiency and dependability. ETI was founded in 1968 and began producing the first Snow Switch® sensing and control products for commercial deicing in the industry. Having been awarded numerous patents for technologies used in snow and ice detection, condensate and humidity control, ground fault and arc detection, energy management, power distribution, and air pressurization systems, ETI has grown into a trusted name worldwide for environmental sensors and controls.
ABOUT ETI FAB
ETI FAB will be a one-stop shop for anything regarding metal fabrication. ETI FAB offers metal fabricated parts and machined components. Their state-of-the-art facility will offer laser cutting, bending, stamping, and welding capabilities in addition to grinding and assembly services. With over 80 years of combined experience, the team at ETI FAB will be able to take on any job no matter how large or small. ETI FAB’s mission is to not only provide the highest quality fabricated products but to follow in ETI’s footsteps and remain a stable employer of Hoosiers throughout the Midwest.
We’re dedicated to our customers
We go above and beyond to help you with your projects.
Our Team | Sales Department 1-800-555-5555
We’re dedicated to our customers
We go above and beyond to help you with your projects.
Sales Department 1-800-555-5555
YES. SIGN ME UP TO WIN A FREE YETI COOLER:
The MCEE Show is where ground-breaking technology is unveiled, innovative solutions are displayed and game-changing trends are exposed.
Prepare to explore aisle after aisle of limitless ideas and inspiration. Only here can you roll-up your sleeves and be hands-on with the products, services and people driving the future of our ever-changing industry.
It’s our last day of having fun in the sun at
#NAB2019 in Las Vegas!
Please visit us outside the Viking Satcom booth # OE9007 to learn how to dare Mother Nature and ensure signal quality with our waveguide and coaxial cable dehydrator line.
Can’t make it to Vegas to register? No problem.
Register here and goodl luck!
Team ETI has been on a whirlwind trip around the globe while spreading the benefits of the ETI product line. In late January, we attended the World of Concrete show in Las Vegas, Nevada. Less than a week later our team was headed off to the far east to attend the Convergence India trade show in New Delhi, India.
Chad Griffin, ETI Director of Sales & Marketing (right), along with Jeremy Crawford, ETI Business Development Representative assisted our strategic business partner’s, Optimum Viking Satcom, by explaining the value and benefits of adding the ETI product line to Southeast Asia telecom & SATCOM infrastructure.
Next, you’ll be able to catch up with the Team ETI at:
NAB ( National Association of Broadcasters )
April 8th – 11th
Las Vegas Convention Center
Las Vegas, NV
April 24th & 25th
Montréal, Québec Canada
If you’re planning to attend either of these shows and would like more information about ETI, our line of environmental controls products and the added value they bring, our team would cherish the opportunity to meet with you and your team at either or both shows.
For the last four days, the ETI Snow Switch Team has been showcasing the newest addition to the Snow Switch product line, the Snow Switch CIT-2, at the World of Concrete convention in Las Vegas, NV.
In addition to the revolutionary design of the CIT-2, what attendees of the World of Concrete were most impressed with is what the unit offers straight out of the box combined.
One of the best features of the Snow Switch CIT-2 is that for the first time in ETI’s 50 year history of engineering snow & ice melt solutions, this is the first unit to be designed specifically to work with the complete line of ETI Snow Switch controllers, as well as, any other comparable unit on the market, or even as a stand-alone unit.
That’s not just groundbreaking, it’s revolutionary.
Click the button below for more information about the Snow Switch CIT-2 Aerial Snow Sensor.
ETI proudly introduces the SNOW SWITCH® CIT-2 Aerial Snow Sensor for surface snow and ice management systems.
The CIT-2 is designed to work with a controller or contactor, optimizing energy usage in heated snow/ice melting applications. The CIT-2 is also an excellent solution for building automation applications.
During dry or warm weather, the system’s heaters are turned off to save energy costs. The heaters are turned on only when snow and/ or ice is present, and kept on only long enough to ensure complete melting and drying. Temperature and time parameters can be varied within the CIT-2, enhancing system performance in a given environment and application.
- Automatic snow sensor for reduced energy consumption in sidewalk, gutter/downspout snow and ice melting applications
- Slim design minimizes visual impact
- Mounts on 3⁄4” PVC conduit for easy installation
- Operates on safe low voltage power
- Simple four wire connections: 2 for power, 1 for signal output
- Wire colors match commonly available cable for easier installation
- Convenient power-on self-test to verify proper sensor
- Made with UV-tolerant and corrosion-resistant materials for
- MADE IN THE U.S.A.
SNOW SWITCH CIT-2 | SPECIFICATIONS
24V AC 50/60Hz, 24V DC, or 24V full wave rectified AC/ pulsed DC 0.2A max
Relay contacts: 2A max, 30V.
|SET POINT TEMPERATURE||
|MINIMUM OPERATING TEMPERATURE||
Selectable -20°F, -15°F, -10°F or disabled for extremely
Set 1 hour
33⁄4 inches tall, 13⁄4 inches diameter
|STORAGE TEMPERATURE||-40°C to +85°C|
Can be mounted 500 feet from the controller using 22ga cable or up to 1,000 ft. using 18ga cable (Depending on load requirements)
February 20th , 2018 (SOUTH BEND, INDIANA) — Ben and Kerri Crawford are excited to announce the acquisition of Environmental Technology Inc. (ETI) located in South Bend Indiana. Born and raised in South Bend, Ben is excited to be back in the area and work in his hometown. When asked, Mr. Crawford said,” It’s great to have a presence where I started my career in Manufacturing 24 years ago. The team at ETI is strong and has an excellent reputation advancing engineered products for snow/ice management, heat tracing and telecommunications reliability and makes me proud to be a part of this industry.”
Ben Crawford has over twenty-four years of manufacturing experience as a C-Suite Executive of Industrial Operations. Ben’s strengths include strategic planning and deployment, global business development, key metric management and continuous improvement objectives.
Kerri Crawford has over sixteen years of entrepreneur experience as the Founder, President and CEO of a successful Indiana based small business in the Commercial Lending Industry. Kerri manages the daily operations and is heavily involved with the strategic vision of the company. Over twenty-two years of commercial lending experience and a dedicated employee focus have been the driving force behind her vision and the company’s success the past sixteen years.
When asked about the future of ETI the Crawford’s indicated, “We remain committed to our customers, vendors, and employees.” “We are excited to assist in growing the business, expanding the product line and working closely with the management team.” They went on to say, “The Jones Family for the past fifty years have built a wonderful company and we are honored to be able to continue ETI’s legacy into the future.”
Launched in 1968, Environmental Technology, Inc. designs and manufactures products for effectively managing the environment. From energy efficient snow melting and deicing to pressurization systems for satellite and microwave transmission lines. ETI has fifty years of experience as an industry leader in developing and delivering effective environmental management systems. Environmental Technology, Inc. has the experience you can count on.
For more information on our products go to https://networketi.com/
For media inquiries, please contact:
Chad Griffin, Director-Marketing Environmental Technology Inc.
How to avoid Snow and ice falling from buildings.
Sheets of snow and ice falling and being blown off buildings are a major hazard that can cause damage to the structure, equipment, and possibly injure someone. Winter conditions have been accounted for in the building design process for a long time, but mostly in a way that only accounts for the weight of the snow and ice acumination and how it will affect the building’s structure. New technologies, innovations, and design trends are requiring that more attention be paid to the dangers of snow and ice when designing and maintaining a building.
Before energy conservation was a big concern buildings were basically large boxes with inefficient insolation that would leak phenomenal amounts of heat that would melt most of the snow and ice almost immediately. Most older building also had simpler designs with smooth walls, and a flat roof with a tall parapet on top to contain snow and ice accumulation so it can be safely drained away. The only real concern back then was how much snow weight could the structure hold, and there were building codes and regulations to account for this.
With advancements in technology, materials, and engineering, buildings are vastly more energy efficient, retaining almost all their heat which creates a colder exterior for snow and ice to accumulate on. Some of these new materials create smooth surfaces snow and ice can slide down in an uncontrolled way causing hazards below. These new materials also allow for more complex building designs, which can create areas where snow and ice can accumulate in unforeseen dangerous ways. These advancements in technologies, materials, and building designs have immense benefits, but also create new problems and hazards which need to be addressed.
The most cost-effective way to address these hazards is in the design phase of the building. There are microclimate professionals that can take data such as local historic weather conditions, surrounding buildings, the building’s airflow patterns, shadow patterns, along with other factors and help identify any potential environmental problems with a building’s design before it is built. These microclimate professionals can also recreate designs in test conditions to see how they perform. It is highly recommended to consult a microclimate professional when designing a building to address potential hazards before the building is built and more expensive fix must be made.
Older buildings will still need to address this problem as they are constantly being upgraded to be more efficient and new buildings being built around them impacting their microclimate. This is where a snow and ice melt system should be installed for safety. Snow and ice acumination that forms in new ways on a building can cause unforeseen consequences. Water can freeze between and behind structures, expanding and causing structural damage. Drainage paths can be overwhelmed in some areas, causing refreezing and accumulation. New areas can become shaded by new buildings in the area causing accumulation where there wasn’t before that needs to be addressed and properly removed. A snow and ice melt system can increase the safety and protection of a building by minimizing the amount of accumulation and keeping drainage paths clear.
Preventing snow and ice buildup is important for the safety of a buildings structure, equipment, and the safety of people below. Whether it is in the design process, or after it is built a building needs to be able to manage snow and ice effectively. Any building’s microclimate should be periodically checked and analyzed to identify and address any problems, especially when they can impact the safety of the people below.
Click Here to view ETI’s Heat Trace and Snow and Ice Melt controls.
Many industries that use hoppers utilize heat trace to aid in material flow. Hoppers are elevated storage containers that contain and dispense granular materials. Commonly used in agriculture hoppers are also used in industries such as plastics, chemical, pharmaceutical, energy, and construction. Despite being used to hold and dispense different types of materials they all function the same way and face the same issues.
The main issues with hoppers focus on the material flow. These issues include aspects related to material sticking together or accumulating on the walls of the hopper. This is commonly caused by the particle structure of the material or the presence of moisture. There are many ways moisture can enter the system, these can be caused by environmental conditions or by water or chemicals being applied to the material in the process before being placed in the hopper.
Major environmental factors that can introduce moisture into the hopper material are temperature and humidity. One way to mitigate this is to install a heat trace system onto the hopper. This controls the temperature of the hopper and material avoiding drastic temperature differences which could cause condensation to form on the inside of the hopper.
The application of water or chemicals to the material or the hopper for dust prevention, cleaning or as a step in the production process add moisture to the material. Moisture such as this should be accounted for in the design and selection of a hopper system to insure proper flow. However, despite accounting for this added moisture in the system variable conditions can still cause flow problems. One major problem for hoppers with chemicals or water added is freezing. Material freezing in a hopper can cause the material to clump together or freeze to the walls, causing a blockage or flow problems. This can cause production to be shut down until the material can be thawed or it is manually cleared out. The presence of a heat trace system in these cases will avoid the freezing and allow the material to flow in a predictable manner, avoiding costly shutdowns or disruptions.
There are many pieces of equipment that can be added to a hopper system to aid in the material’s flow such as augers and vibration units, but to combat the effects of variable environmental impacts a heat trace system should be included.
Click Here to check out ETI’s Tracon Heat Trace controls.
Visit us at the 2018 NAB Show in Las Vegas, April 9th through the 12th. ETI will be presenting at the Viking Satcom booth #OE11045. Come out and see our ADH NETCOM and NETCOM NEMA on display and talk with ETI’s Dennis Sizemore and Chuck Gartland. Please contact your sales representative in advance to reserve a time to meet by
emailing firstname.lastname@example.org, or calling (574) 233-1202.
Thank you and we look forward to seeing you there.
While at the NAB journey through 1,700 Exhibitors within the Las Vegas Convention Center. From established, global brands to up-and-coming innovators, this collection of ground-breaking tools and solutions are set to form the next generation of storytelling.
Stop by and enter to win a Yeti cooler from ETI and Viking Satcom.
Satellite antennas radiate signal energy in distinct patterns that are reported as their radiation pattern envelope. These patterns consist of lobes which indicate the intensity of signal radiation radially on a horizontal plane emanating from the antenna. These patterns of signal strength are measured including both horizontal and vertical polarizations at three frequencies which represent the bottom, middle and top of the antenna’s band.
When the radiation signal strength is measured, a main lobe will indicate the main direction of the signal beam. This main lobe indicates the direction the signal will be effectively transmitted. The size of the lobes representing the strength of the signal will decrease as they get further from the main beam. Side lobes appear as small surges in signal radiation adjacent to the main beam. These side lobes can result in unwanted signal noise which can also reduce the antenna’s carrier signal.
The signal capacity of an antenna can be determined by dividing its carrier signal strength by its signal noise. Better antennas produce a better signal by creating minimal side lobes which reduces signal noise and increases the signal capacity. Antennas of lesser quality which have larger side lobes which diminish the antenna’s signal capacity. There are however ways improve an antenna’s signal capacity.
There are two main approaches to increasing an antenna’s signal capacity, increasing the carrier signal strength by increasing the transmission power, or by decreasing the signal noise. Increasing an antenna’s transmission power seems like an obvious solution, but it comes with added energy costs, and might not be applicable due to increased interference, regulatory restraints, and infrastructure limitations. Another way to increase the signal strength is to install a larger antenna, but installing a larger antenna is expensive, requires more maintenance, power, and a larger infrastructure. When increasing signal strength is too costly or not applicable decreasing the signal noise is an option. Simply realigning the antenna creating a different link path can drastically improve an antenna’s signal capacity, this is a low-cost way to decrease signal noise. The best solution would be to purchase an antenna that produces small side lobes. These are higher quality antennas that produce less signal noise resulting in a more optimized signal capacity.
Consulting an antenna’s radiation pattern envelope is important for selecting the right antenna for an application and important in designing and installing a communications system. Antenna manufactures publish radiation pattern envelope information for their products and make them available for review. When selecting, designing, installing, optimizing or troubleshooting an antenna or communications system always consider the antenna’s signal capacity by reviewing its radiation pattern envelope.
Heat Trace with Plastic Pipes
Heat cable can be used on plastic pipes but the plastic’s durability and thermal properties must be considered. Plastic has approximately 125 times the thermal resistance than steel but is also more susceptible to damage from direct high temperatures. The key to heating plastic pipes is to use a lower temperature and distribute it as evenly as possible.
It is always a good idea to use a heat trace system with an automatic thermostat and control, but especially so when using heat trace on plastic pipe. An automatic heat trace control can monitor and maintain the system’s temperature, alarm for problems, and shut off the heat cable to prevent damage.
There is heat cable designed specifically for plastic pipes that is self-regulating and has limited wattage. Self-regulating heat cables have a conductive core between two bus wires that becomes more conductive when cold. This system increases the power to the cold spots and decreases it to the warmer areas, which provides a more even heat source.
The manufacture of the plastic pipe should be able to provide information as to the maximum temperature and how close heat cable can be spaced or wrapped on the pipe to avoid damage. Some applications may require heat cable to be applied to opposite sides of the pipe at a lower temperature to distribute the heat more evenly, avoiding one direct area of concentrates heat which may damage the pipe.
It is recommended to install a foil material between the pipe and the heat cable to avoid direct contact and help provide a more even heating. If doing this place the heat trace control thermostat directly onto the pipe with no foil over it or between it and the pipe to ensure a more accurate reading.
You can use heat cable on plastic pipes as long as you follow precautions, such as determining your pipe’s thermal capacities, selecting a self-regulating, low wattage heat cable and using an automatic heat trace control with safety functions. Following these guidelines will help prevent damage and increase the life of your heat trace system.
Considering environmental impacts of snow and ice melt maintenance.
There are environmental costs involved with any snow and ice melt system, knowing and assessing these environmental costs can help you choose the snow and Ice maintenance system that will work best for your needs and environmental conditions.
Electric or hydronic snow and ice melt systems
Electric and hydronic snow and ice melt systems can be a large investment but offer a cleaner, complete, uniform melt that can be easily monitored and controlled automatically or manually. With electric and hydronic melt systems, the only environmental impact is from the energy used to heat the heater cables or fluid in the heating pipes. Modern snow and ice melt controls implement energy-saving technologies that can help reduce their operating cost and environmental impact.
Electric and hydronic melt systems also can consistently heat places where chemical snow and ice deicers would be damaging or impractical, such as on roofs and in gutters.
Chemical deicers are very common. They are versatile, require no initial setup or permanent installation and can easily be regulated and modified. However, there are several drawbacks to using chemical deicers. Chemical deicers can be corrosive and can impact the environment through runoff, absorption, and air transportation.
Chemical deicers are divided into three main types, chloride-based deicers, acetate-based deicers, and carbohydrates.
Chloride-based deicers, commonly known as salt deicers, are composed of Chloride (an anion) and either sodium, magnesium, or calcium (a cation). When chloride-based deicers dissolve, the anion and cation dissociate impacting the environment in different ways.
Chloride is corrosive, meaning it can deteriorate a material by chemical reactions. Chloride does not biodegrade or absorb into material easily, so it can accumulate changing the fertility and acidity of the soil, damage plant life, and enter ground and surface water.
Sodium, magnesium, and calcium effect soil and plant life differently. Sodium changes the structure of the soil, decreasing permeability, and infiltration. Sodium also increases the alkalinity of the soil, which reduces the magnesium, calcium, and other nutrients for plant life. Magnesium and calcium can be good for the soil and plant life by adding nutrients. Sodium reduces the hardness of water, again reducing the magnesium, calcium, and other nutrients and metals. Magnesium and calcium increase water’s hardness (increases mineral content), they can also decrease the toxicity of heavy metals in the water.
Acetate-based deicers, sometimes referred to as pet-safe deicers are less corrosive and are not as toxic to plants and wildlife than chloride-based deicers and. The most common type of acetate deicer is calcium-magnesium acetate, otherwise known as CMA. The characteristics of CMA indicate that it is mostly absorbed by soil surface, minimizing the amount that would be carried away by runoff to surface water or enter ground-water.
Since most of the acetate-based deicer runoff is absorbed by soil only a limited amount enters the water system where it’s effects can be minimized by dilution, larger moving bodies of water will be affected less than small stagnant bodies of water. When it does enter a water system in large enough concentration it increases the biological oxygen demand on rivers and lakes, creating a potential threat to aquatic life.
Carbohydrate-based deicers do not melt snow and ice, they reduce the reduce the freezing point of ice further than Chloride-based deicers, and can help deicers better stick to the surface. Carbohydrate-based deicers are relatively safe for the environment, except they do pose a similar increase in biological oxygen in lakes and rivers as acetate-based deicers. Carbohydrate-based deicers can also be used with chloride-based deicers to mitigate their corrosive nature.
Desiccant vs Membrane Dehydration. Two of the main types of dehydrators are used for waveguide dehydrators, desiccant dryers, and membrane dehydrators. Both effectively remove moisture from the air but do it in vastly different ways.
A waveguide is a tube-like structure that allows for the guided flow of electromagnetic waves with minimal energy loss. The waveguide must be clean and free of debris and humidity, because these can distort the wave, negatively impacting signal quality.
Waveguide dehydrators are commonly used to pump clean dry air into the waveguide to reduce the humidity. Two of the main types of dehydrators are used for waveguide dehydrators, desiccant dryers and membrane dehydrators. Both effectively remove moisture from the air, but do it in vastly different ways.
Desiccant dryers dry by passing the air through a container of a desiccant material. Dry air passes through the desiccant material while moisture adheres to the desiccant material. This process requires the desiccant to regenerate, which is the process of drying out the desiccant for further use. There are two ways the desiccant can be regenerated, with heat, and heatless. Regeneration with heat method uses an internal heating element to heat the desiccant material, which converts the moisture into steam that can be vented with pressurized dry air. Heatless regeneration uses purely the dry pressurized air to dry the desiccant.
Membrane dehydrators use a permeable membrane that will allow water to pass through, but not the larger oxygen and nitrogen molecules which is the prevalent molecule in air. The pressure would push the water molecules through the membrane while retaining the dry air.
Membrane dehydrators require less maintenance, but require higher pressure and cannot reach as low dew point as a desiccant system. A desiccant system can dry air to a lower dew point and requires less pressure, but needs to have it’s desiccant canisters replaced every 3 to 5 years, or more depending on use.
Both these methods of dehydration are applicable for waveguide dehydration system. It is important to assess your systems requirements and environmental conditions before selecting a proper dehydration unit. Please feel free to contact Environmental Technology or any of our partners here.
The overall purpose of the dehydrator is to eliminate moisture in the waveguide of the transmitter. Moisture will affect the reflected energy and increase the Standing Wave Ratio (SWR) of the system.
Dehydrators deal with moisture in waveguides differently than systems pressurized with inert gasses.
In pressurized systems, the system is sealed and moisture is kept out by the same seal that keeps the gas in. If the pressurized system develops a leak the inert gas leaks out and moisture can then accumulate in the system. In most cases, these pressurized systems then need to be re-pressurized in order to find and repair the leak, then be evacuated with a vacuum pump and refilled with the inert gas. This can become a long and expensive process.
In comparison, a dehydrator supplied waveguide is constantly having the air in the waveguide replaced with desiccated air and its pressure is varying from the low set point to the target set point. This delta P is the operating pressure for the system.
The operating pressure (∆P) is determined by the wave guide’s manufacturer’s recommended max pressure and the lowest pressure the customer is comfortable with as a minimum to the system. The max pressure is generally dictated by the feed horn window material.
- Low pressure alarm – this is the level at which the unit will present an alarm. This needs to be lower than the low limit pressure
- Low Limit Pressure – this is the level that will cause the dehydrator to start the compressor to pressurize the system. This must be at least .1 PSI lower than the High Limit Target Pressure
- High Limit Target Pressure – this is the level that the compressor will be turned off at.
- High pressure alarm – this is the level at which the unit will present an alarm. This needs to be higher than the High Limit Target Pressure
Perfectly sealed systems are not only difficult to manufacture but impossible to maintain over time. For this reason, ETI strives for perfect seals but accepts very small leaks in the system as normal. Our maximum allowable leak rate on a new system is .04 psi per minute on a system pressurized at 7.5 PSI. With a dehydrator’s outlet completely blocked off this would translate to a leak downtime of 2.5 hours or more if there is a ∆P of 6 PSI between the low limit pressure and the high limit target pressure.
It should be noted that the leak downtime is dependent on the ∆P. For example, the same leak rate of .04 PSI will take 2.5 minutes when the ∆P is .1 PSI.
For this reason, it is important to understand the relationship between the ∆P, leak rate & duty cycle. To do this also requires an understanding of how the duty cycle is calculated and what it means.
The duty cycle is calculated by averaging the time of two compression cycles using the time the compressor is on divided by total time (time compressor on and time off between cycles). The on time is going to be affected by a number of variables but the two most important variables are the volume of the waveguide and the flow rate of the compressor.
There is no hard and fast rule as to what duty cycle you should have on your dehydrator; it is entirely up to the customer to determine what is best for their application. In doing so it should be considered that once set, a change in the duty cycle indicates a change in the system/ waveguide. Setting the duty cycle alarm to approximately two times the selected duty cycle will allow the system to give the customer an alarm indicating a problem with the system.
Setting the duty cycle is accomplished by changing the waveguide bleed (normally mounted on or near the feed horn) to allow a constant managed leak of the system.
Netcom compressors have a flow rate of 10 liters per min so for small systems (1l or less) you are looking at only a few seconds of compressor time for a complete fill and fractions of a second for satisfying the ∆P requirements for operating pressure.
For these reasons, it is possible to have a NETCOM pressurizing a small system with a very small ∆P that will run the compressor every 10 to 15 seconds for a period of a fraction of a second. At first, this may appear to be an internal leak on the NETCOM but looking at the duty cycle and alarms you will be able to determine that the N ETCOM is simply working normally at a 5% duty cycle.
It would be advisable to reduce the duty cycle to as low as 1% for small systems in order to increase the time between compression cycles. This will also allow the casual observer to feel the system is operating normally without internal leaks or issues.
Another way to accomplish this is, of course, to increase the ∆P on the system slightly if the system will allow it. Again the limiting factor is the feed horn window max pressure limitations.
As an example:
If a system is initially set to a 1% duty cycle and the duty cycle alarm is set for 2% and after several months of operation the duty cycle alarm is indicated the operator has a number of options. He can start looking for the leak, find and fix it immediately or determine that the leak is small enough to not warrant immediate action because there has been no effect on the SWR of the system. The dehydrator has compensated for the leak with increased duty cycle. At this point, the operator may bump the duty cycle alarm up to 3%, report the issue and put it on the agenda for future maintenance on a remote site.
Comparing the above example to an inert gas pressurized system the leak would leave the system open to atmosphere and SWR would be affected necessitating an immediate repair.
Heat-trace is used in many aspects of everyday modern life that mostly goes unnoticed. One main example of this is the ability to access hot water quickly from any faucet in a large building no matter how far from the water heater it is. This is a function of a building’s Hot Water Maintenance system. heat-trace is just part of a comprehensive Hot Water Maintenance system. Other components of a Hot Water Maintenance are the water heater, hot water storage tanks, a circulation loop and a pressure release.
Hot Water Maintenance is important for many reasons, one of the most important reasons is to sanitize. Hot water helps to prevent diseases, like Legionnaires Disease by killing the bacteria that causes it and preventing it from multiplying within the pipes. Water that is too hot can lead to injury. It is important to have the temperature set within a safe range. Keeping the water hot throughout the pipes will also reduce water and energy waste by not having to run the water before reaching the hot water.
Heat-Trace systems consist of a heat cable (heat tape) and control. There are two types of heat cable, self-regulating and constant wattage. Self-regulating cable does what it says, it regulates itself to an extent. It does this with a special conductive material core between two bus wires. The core’s conductive nature varies with temperature, the cooler it gets the more conductive it becomes which increases the heat the cable gives off, the warmer it gets the less conductive it becomes resulting in the cable giving off less heat. Constant wattage heat cable provides a uniform distribution of wattage, resulting in uniform heating along the whole cable. Self-regulating cable will save energy, where constant wattage cable will heat in a more uniform precise way. Both self-regulating and constant wattage heat cable require a heat-trace control unit to regulate the temperature and monitor and alarm for errors.
Hot Water Maintenance systems are a hardly noticed element of our everyday lives that make our modern lifestyle possible. Heat-trace is a critical component of these systems, keeping the water hot within the pipes. Next time you are in a building pay attention to the hot water and think about what makes that possible.