11 September 2012

Electrical Interview Questions And Answers Part 3

Reference: www.rsiwind.com

Subject: Wind Turbine

Q: What makes the TechnoSpin such a “Great Buy”?
A: The TechnoSpin combines a high output generator at a great price, so when you take a look at the cost per kw, it is an amazing turbine that the manufacturer will stand behind and will produce years and years worth of electricity for you.
The TechnoSpin can be used on-grid or off-grid, just let us know which application works best for you and we’ll set the unit up to meet that need; whether your charging battery’s for back-up power or connecting on-grid to off-set your current usage, the TechnoSpin will be there, producing for you.

Q: What are the advantages of the VBINE Unit?
A: Accessibility ~ With a light and compact design, the VBINE mounts easily on to existing buildings, enabling power generation wherever energy is used.  It can support urban environments, farms, high-rise buildings, communication towers, factories… the possibilities are infinite.
High Performance ~ with no tail fin the VBINE is ALWAYS  in the prime wind direction, if conventional turbines aren’t facing the exact direction of the wind, they aren’t getting 100% of the winds full potential power transferred to the generator.  The VBINE solves this problem by taking wind from any direction.
Installation ~ The VBINE can be installed on almost any location that uses power, on top of existing towers, on top of existing buildings, on top of power poles.  The low weight of the unit and unique design allow it to easily be installed in almost any location that you can think of.  If you’ve got a location with good wind, then you’ve got a good VBINE location.
Strength ~ just like the WindGen, the VBINE is an extremely tough and durable unit, it’s made of stainless steel structural components and carbon fiber blades – carbon fiber is one of the premier materials on the market when it comes to strength vs weight, meaning you can get the strength of steel, but at a significantly lower weight.  When it comes to turning blades with the wind, weight is an issue, so if you can’t have steel, then Carbon Fiber is just as strong, but with a lower weight which will increase productivity

Q: Why should I install a Wind Turbine?
A: 
WindGen systems can provide consumers in windy locations with a cushion against electric power price increases. Depending on your location, a WindGen system can lower your electricity bill and help you avoid the high costs of having utility lines extended to remote locations. Wind energy systems not only help you reduce your electricity cost, they also allow you to Go Green by helping to reduce dependence on fossil fuels, and they are non-polluting. Over its lifetime, a WindGen turbine can offset approximately 2-4 tons of air pollutants and up to 400 tons of greenhouse gases.

Q: Many places refer to Meter/Second (M/S). How do I convert that to MPH?
A: The formula is 1 M/S = 2.237 MPH . Example: 10 M/S = 22.369 MPH

Q: What is "net metering"?
A: We refer to net metering as "on grid" wind power generation. In short, it allows you to connect your wind turbine to your electrical meter. Any excess power that you produce, in effect, runs your electrical meter BACKWARDS. 

Q:  How much energy will my system generate?
A:  Most U.S. manufactures rate their turbines by the amount of power they can safely produce at a particular wind speed, usually chosen between 27 mph and 37 mph with a higher start up speed of 7mph. The WindGen is rated at 25mph (10KW) with a very low startup of 4 mph.  In fact the WindGen will produce 15.8KW and keep producing that in high wind, where all the others will have to shut down. Being able to keep producing full output in high wind is an area that has not been address in yearly output planning by any groups like AWES or NREL. All the units on the market today have to start to shut down above 35 to 40mph. Look at the others wind charts, in-fact they have to start reducing their output greatly, which lowers their yearly output even more.  The RSI WindGen provides the max return on investment to you yearly in any wind.


Q: Can RSI Wind Turbines go “off-grid” and can I add solar too?
A: Yes, off-grid hybrid wind energy systems can be appropriate for homes, farms or entire communities that are far away from the nearest utility lines. According to many renewable energy experts, a “hybrid” system that combines wind photovoltaic (PV) technologies offers several advantages over either single system. This is built into the WindGen controls, so you can change or add as you need later on, you can even add a back up Gen/Set (generator).
WindGen Off-Grid System
WindGen Off-Grid System

Q: How much does a system cost?
A: A general rule of thumb is that a small system can cost from $2,500 to $8,000 per kW. But be aware that most wind companies that sell wind units do not have “turn-key” packages and the tower, batteries, inverters,  foundation, installation and permitting costs can add another 50% to 100% or more to the purchase cost. Also, maintenance costs which might range between 1-3% of the initial installation cost.   The RSI package has it all for one price.

Q: Can I use my own tower and buy just the head?
A: The turbine and tower system are designed as an integral, joint unit to account for all loads on the system. The standard unit is on an 80 foot tower which is much larger than older towers that you might have. Therefore, the tower and turbine must be purchased together for the five-year Warranty to be valid. The standard 10KW WindGen has a 25 foot head.
Not Your Granddad's Windmill!
This is the gearbox for the head on 40 foot truck trailer (This is not your granddad's windmill!).
The 2.2kw & 4kw TechnoSpins CAN be installed on existing wind mill towers or tall structures that you may have on your property, but only after RSI has reviewed the structure for structural stability – this would typically be a self-install situation.

Q: Is wind energy practical for me?
A:
 A WindGen system can provide you with a practical and economical source of electricity if:
    • Your property has a good wind resource
    • Your home or business is located on at least one acre of land or in a rural area
    • You are able to have adequate set backs between the turbine and buildings, roads, and property lines; minimum set backs equal to the total wind structure height are generally recommended


    Q: How much space do I need to install a WindGen?
    A: A variety of factors such as: the size of the foundation, distance from inhabited buildings, zoning requirements, set back distance from property lines, etc. must be considered in order to determine the amount of space needed. Typically, a standard Windgen is on a 16’ x 16’ foundation with 18”-24” drill footers 8’ to12’ deep depending on tower configuration and soil type.
    Windmill
    Tower Height:
    Obstruction by Trees or Buildings
    The ideal turbine height is the rotor + 2x obstacle height, but……the ideal may not be practical.
    Obstruction by Trees or Buildings
    The entire rotor should be at least 30’ above the trees and buildings. 


    Q: Is the WindGen suitable for coastal applications?
    A: Yes, our turbines are TIA rated for coastal environments.

    Q: Is lightning a problem with the WindGen?
    A: All towers and Wind turbines carry an inherent risk of lightning damage due to their height.  The WindGen is built to hardened Mil spec and installed like telecom towers with proper grounding at key points to mitigate damage from lightning strikes. RSI has years of work on telecom grounding generally, damage from lightning strikes is minimal.

    Q: Do wind turbines harm birds?
    A: Both, the Audubon Society in California and the Department of Natural Resources in Wisconsin and others have issued letters stating that due to size, most small turbines do not require an environmental study regarding impact on bird populations.
    Bird mortality has been absent to very low at all newer generation wind plants studied in the U.S. The National Wind Coordinating Committee (NWCC) completed a comparison of wind farm avian mortality with bird mortality caused by other man-made structures in the U.S., and found that commercial wind turbines cause the direct deaths of only 0.01% to 0.02% of all birds killed by collisions with man-made structures and activities. Early wind turbine machines and still some today, spun faster than the WindGen and therefore did pose problems for birds. Bird collisions with the WindGen’s are very rare if at all we know of no known bird kills. 

    Q: How long after a WindGen turbine is purchased, will it be installed?
    A: You can expect the WindGen will be installed approximately 60 days after the purchase date.

    Q: Do I need a building permit to erect the Windgen?
    A: Building permit requirements vary according to site location and application. Permitting requirements are determined Site Analysis by RSI WIND 
    Q: How close can a wind tower be installed to an airport?
    A: According to FAA regulations, turbines under 200 feet do not require lighting if they are more than 20,000 feet away from an existing runway. The FAA does require notification if the turbine is sited within 20,000 feet of an existing runway. These types of issues would be addressed in RSI’s Wind’s Feasibility Studies to ensure all regulations are adhered to.  RSI has years working with large telecom towers, so we know how to deal with this.
    Most installs do not require any FAA approval.

    Q:  What are the advantages of the VBINE Unit?
    A: Accessibility ~ With a light and compact design, the VBINE mounts easily on to existing buildings, enabling power generation wherever energy is used.  It can support urban environments, farms, high-rise buildings, communication towers, factories… the possibilities are infinite.
    High Performance ~ with no tail fin the VBINE is ALWAYS  in the prime wind direction, if conventional turbines aren’t facing the exact direction of the wind, they aren’t getting 100% of the winds full potential power transferred to the generator.  The VBINE solves this problem by taking wind from any direction.
    Installation ~ The VBINE can be installed on almost any location that uses power, on top of existing towers, on top of existing buildings, on top of power poles.  The low weight of the unit and unique design allow it to easily be installed in almost any location that you can think of.  If you’ve got a location with good wind, then you’ve got a good VBINE location.
    Strength ~ just like the WindGen, the VBINE is an extremely tough and durable unit, it’s made of stainless steel structural components and carbon fiber blades – carbon fiber is one of the premier materials on the market when it comes to strength vs. weight, meaning you can get the strength of steel, but at a significantly lower weight.  When it comes to turning blades with the wind, weight is an issue, so if you can’t have steel, then Carbon Fiber is just as strong, but with a lower weight which will increase productivity.


    Q: What is "Wind capacity factor"?
    A: Capacity factor is one element in measuring the productivity of a wind turbine or any other power production facility. It compares the plant's actual production over a given period of time with the amount of power the plant would have produced if it had run at full capacity for the same amount of time.
                            Actual amount of power produced over time
    Capacity Factor =
                             Power that would have been produced if turbine operated at maximum output 100% of the time
    A conventional utility power plant uses fuel, so it will normally run much of the time unless it is idled by equipment problems or for maintenance. A capacity factor of 40% to 80% is typical for conventional plants. A wind plant is "fueled" by the wind, which blows steadily at times and not at all at other times. Although modern utility-scale wind turbines typically operate 65% to 90% of the time, they often run at less than full capacity. Therefore, a capacity factor of 25% to 40% is common, although they may achieve higher capacity factors during windy weeks or months. But the RSI WindGen also never shuts down, even in high wind. In fact the Windgen can produce up to 15.8 KW in high wind when all the other units have had to shut down. It is important to note that while capacity factor is almost entirely a matter of reliability for a fueled power plant, it is not for a wind plant—for a wind plant, it is a matter of economical turbine design. With a very large rotor and a very small generator, a wind turbine would run at full capacity whenever the wind blew and would have a 60-80% capacity factor—but it would produce very little electricity. The most electricity per dollar of investment is gained by using a larger generator and accepting the fact that the capacity factor will be lower as a result. Wind turbines are fundamentally different from fueled power plants in this respect.

    Q: What is a KW and what is KWH?
    A: The ability to generate electricity is measured in watts. Watts are very small units, so the terms kilowatt (kW, 1,000 watts), megawatt (MW, 1 million watts), and gig watt (pronounced "jig-a-watt," GW, 1 billion watts) are most commonly used to describe the capacity of generating units like wind turbines or other power plants.
    Electricity production and consumption are most commonly measured in kilowatt-hours (kWh). A kilowatt-hour means one kilowatt (1,000 watts) of electricity produced or consumed for one hour. One 50-watt light bulb left on for 20 hours consumes one kilowatt-hour of electricity (50 watts x 20 hours = 1,000 watt-hours = 1 kilowatt-hour).

    Q: How many homes can one megawatt of wind energy supply?
    A: An average U.S. household uses about 10,655 kilowatt-hours (kWh) of electricity each year (note, the RSI WindGen can produce up to 20,000KWH with good wind). One megawatt of wind energy can generate from 2.4 to more than 3 million kWh annually. Therefore, a megawatt of wind generates about as much electricity as 225 to 300 households use.

    Q: Does the wind turbine meet the proposed American Wind Energy Association Small Wind Turbine Performance and Safety Standard?
    A: Yes, our turbines have been tested to the current standards, however at this time there is no “certification” available from AWEA. AWEA has been working on a performance and safety standard for a number of years; with the initiative approaching completion, hopefully the standard will be adopted sometime in 2009 and used by the Small Wind Certification Council (SWCC) to certify small wind turbine equipment. (The SWCC is composed of a wide array of stakeholders, including industry members, installers, government officials, and public benefits program representatives.)

    Q: Will the WindGen wind mill pump water too?
    A: Yes, The WindGen turbine can be used in applications such as pumping water. Wind energy has been used for centuries to pump water and grind grain. Although mechanical windmills still provide a sensible, low-cost option for pumping water in low-wind areas, farmers and ranchers are finding that wind-electric pumping is much more versatile and they can pump twice the volume for the same initialinvestment. In addition, mechanical windmills must be placed directly above the well, which may not take the best advantage of available wind resources. Wind-electric pumping systems can be placed where the wind resource is the best and connected to the pump motor with an electric cable.

    Q: Can I use a 30’ tower?
    A: Because wind speeds increase with height, the turbine is mounted on a tower. In general, the higher the tower, the more power the wind
    system can produce. The tower also raises the turbine above the air turbulence that can exist close to the ground because of obstructions
    such as hills, buildings, and trees. A general rule of thumb is to install a wind turbine on a tower with the bottom of the rotor blades at least
    30 feet (9 meters) above any obstacle that is within 300 feet (90 meters) of the tower. Relatively small investments in increased tower height can yield very high rates of return in power production. For instance, to raise a the WindGen from a 60-foot height to 92-foot involves a 12% increase in overall system cost, but it will produce over 25% More power.  RSI’s recommends the 80’ tower which puts the wheel at 92’ Notice that the wind speed, V, has an exponent of 3 applied to it. This means that even a small increase in wind speed results in a large increase in power. That is why a taller tower will increase the productivity of any wind turbine by giving it access to higher wind speeds as shown in the Wind Speeds Increase with Height graph.

    Q: Why do you want the tower up so high?  The wind blows at ground level also!
    A: The wind blows much stronger the higher up you go. 
    Consider the following:  
    ~ The higher the turbine is, the more “fuel” it has (wind)
    ~ A 10% increase in Wind Speed = 33% more power
    ~ Doubling the wind speed = 8 times the power!!!!
    ~ The more energy you produce = a faster Return on Investment
    ~ The tower must be up high, in the smooth, unturbulent air, away from trees & buildings.  You wouldn’t try to fly a kite in a forest or in-town in between the buildings… the same thing goes for your wind turbine, it needs to be in a logical open spot.


    The formula for calculating the power from a wind turbine is:
    Power = k Cp 1/2 ñAV3 Where:
    P = Power output, kilowatts
    Cp = Maximum power coefficient, ranging from 0.25 to 0.45,dimension less (theoretical maximum = 0.59)
    ñ = Air density, lb/ft3
    A = Rotor swept area, ft2 or π D2/4 (D is the rotordiameter in ft, π = 3.1416)
    V = Wind speed, mph
    k = 0.000133 A constant to yield power in kilowatts. (Multiplying the above kilowatt answer by 1.340 converts it to horsepower.
    [i.e., 1 kW = 1.340 horsepower]).



    Q: How do you calculate Carbon Credits?
    A: At this time, the exact method of calculating a Carbon Credit is still a bit of a moving target.

    Earn Carbon CreditsBelow is 1 method of calculating a Carbon Credit:
    1 KWHR = 1.535 lbs CO2 (Carbon Dioxide)
    1,302 KWHR’s = 2,000 lbs of CO2 (Carbon Dioxide)
    2,000 lbs CO2 = 1 ton of CO2 = 1 Carbon Credit = 1,302 kWhrs

    As the Carbon Credit market develops along, these values will most likely change.

    Q: If 1 kwh of power saved then how many carbon credit will be earned?
    A: 1000 Kilowatt per year = 520Kg CO²
    2000 kilowatts approximate = 1 tonne CO² = 1 Carbon Credit




    Q: Will Static electricity build-up from the blades moving through the air affect the WindGen?
    A: An all steel structure & steel blades (WindGen only) are at the same potential as the rest of the tower, eliminating static build-up. Fiber-glass blades could increase the potential for static electricity build-up & disturb radio fields.

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