Description

The StealthGen Wind Generator is a new direct-drive wind generator, designed for a variety of microgeneration applications. It is exceptionally quiet and vibration-free in operation, qualities that are of paramount importance for any wind generator operating in close proximity to people. The StealthGen features a powerful 3-phase alternator, and computer-designed rotor blades optimised for low speed, user-friendly operation.

This innovative machine is extremely efficient in low wind speeds, yet is capable of sustained power outputs of over 500 watts in higher winds.

It is small and light enough to be easily attached to most building structures. Given average wind speeds at the site of around 12 mph, one D400 StealthGen could realistically provide 15 – 20% of the average home’s annual electricity requirement.

Inexpensive to purchase and virtually silent in operation, once installed the StealthGen is no more conspicuous than a satellite dish.

Distinctive and elegant in design, the StealthGen is superbly engineered for long, trouble-free service, and is available in 12, 24, 48,72  or 150 volt grid-connect variant.

Due to the StealthGen’s low cost, it is perfectly feasible to install several machines.

Environmental:

Small wind turbines sited within the urban environment have the potential to make a significant contribution to the attainment of fuel poverty and carbon abatement targets.

Eclectic Energy Limited has worked closely with INREB Faraday, the NGO tasked with the development of these technologies.

Conventional wisdom has largely precluded the mounting of wind generators on buildings due to the unacceptable noise and vibration associated with such installations. Eclectic and its research partners have overcome these problems in the development of the D400 and StealthGen technology.

The power produced can be used for:

Grid connect – G83 inverter technology

Battery inverter AC systems

DC direct supply to fluorescent lighting

DC supply water heating

Battery charging (transport)

Hybrid ground source heat pump systems

Hybrid micro wind/ photovoltaic systems

Power
produced
CO2
Abatement
1 x D4001 Year660 kW hrs.0.27 tonnes
25 year Lifespan16,500 kW hrs.6.75 tonnes
1000 x D400s1 Year660 MW hrs.270 tonnes
25 year Lifespan16,500 MW hrs.6,750 tonnes
1,000,000 x D400s1 Year660,000 MW hrs.270,000 tonnes
25 year Lifespan16,500,000 MW hrs6,750,000 tonnes
Specifications

D400 Wind Turbine Specifications

Performance

Rated power235 W @ 11 m/s (22 knots), 420 W @ 14 m/s (28 knots)

Power outputs

Maximum power600 + W
 Rotational speed1100 rpm @ 14 m/s
 Cut-in speed2.5 m/s (5 knots)
 Cut-out wind speedNone

Turbine features

Turbine typeHorizontal axis upwind
 Number of blades5
 Airfoil typeLow Reynolds – variable camber
 Diameter of turbine1.1 m
 Swept area0.95 sq. m
 Tip speed ratio4
 Typical noise level2 – 6 dbA over background
 Blade materialGlass-filled nylon

Alternator

Alternator typeDirect drive – axial field
features12 pole permanent magnet generator
 Design3-phase AC with rectification
 Outputs direct current (DC)
 Annular high energy magnet rotors
 Encapsulated stator windings
 Voltages availableDC: 12 V, 24 V, 48 V, 72 V
 AC: 240 V grid connect via inverter
 MaterialsAluminium alloy housing, hermetically sealed
 Alocrom 1200 corrosion protection and polyester powder coat
 316 stainless steel shafts and A4 stainless fasteners
 EMI (electromagnetic emissions)C.E. compliant
 MCS AccreditationPending
 Control systemStall regulation
 Brake systemElectromagnetic braking switch

Yaw system

PassiveLow resonance, formed aluminium tail
 Heavy duty slip ring assembly with saddle spring loaded output brushes
 Turning circle700 mm

Mounting

Typical stub tower50 mm – 75 mm O/D

Weight

Total17 kg

Finish

Colours availableWhite with white blades
 Black with translucent blades
Performance & Expectations

System Performance

1) Unlike many other grid tied micro generation systems, StealthGen power electronics are wholly powered by DC power from the wind turbine. Other systems power the electronics from the mains and this means a continual, albeit low, draw from the grid even during periods of low or zero wind. StealthGen draws nothing from the grid in these conditions.

2) Airborne noise – the StealthGen wind turbine should be virtually inaudible in normal operation. Typical sound emission levels are between 30 – 40 db. If there is a distinct whistling or shrieking noise from the air blades, this could indicate that the turbine is over speeding due to a fault in the system (i.e. an open circuit condition caused by a poor connection). Erratic yaw behaviour, where the turbine keeps turning away from the wind, is also symptomatic of a possible open circuit fault.

3) Vibration and mechanically transmitted noise – in normal operation, there should be very little noise or vibration evident inside the building. If noise and vibration are continually present, this may indicate a turbine fault such as a loose or worn air hub, a damaged air blade or failing bearings. Occasional vibration, associated with very high or gusty wind, is probably due to resonance in the turbine tower. This can be addressed by adding stays to the tower to prevent its flexing, or by reducing the height of the turbine (i.e. shortening the tower) or by using a stiffer tower tube.

4) Power Output – the output from a micro wind system varies continually due to fluctuations in wind speed and direction. For this reason, many conventional cumulative kW hour meters fail to record system output accurately, and typically substantially under read. Power meters with a high sample rate are required for accurate metering. Refer to Eclectic Energy Limited for further information.

5) Multiple systems – two or more StealthGen turbines can be successfully installed where more power is required. Turbines should be mounted at least 2.75 metres apart where the turbines are perpendicular to the prevailing wind direction. This spacing should be increased to 4 metres plus where the turbines are in line with the prevailing wind, and also the mount height raised if possible. Avoid mounting in the centre of flat-roofed buildings. Always aim to mount at a point nearest to the direction of the prevailing wind.

Performance and Power Output

Refer to D400 manual for the wind turbine power curve. Estimated annual power yields are represented below.

Thstealthgen-est-annual-generatione StealthGen / D400 wind turbine is very robustly engineered and will operate safely in all typical wind speeds. It is generally preferable to allow the turbine to operate normally even in very high winds.

The brake switch on the control/ interface unit may prove ineffective in wind speeds above 18m/s (40 mph), and should therefore not be used in these conditions as damage to the turbine can result. Also the brake switch should not be treated as a parking brake for the same reason.

Refer to the D400 Manual for further information on the brake switch and high wind speed strategies.

*All performance figures are indicative. Actual outputs may vary. E&OE.

Installation

StealthGenBuilding Mounting:

Eclectic StealthGen turbines can be successfully mounted off structural walls (typically the gable wall) using the specially designed bracketry illustrated. Drawing A (and photograph Aa) shows a typical standard duty installation, secured by 4 x M10 masonry anchors, and provides for a maximum free tower length of 2.5 metres. Refer to ‘Standard Bracket Installation’ section.

Where a greater free tower length is required, i.e. up to 4.5 metres, the heavy duty bracket system (see photograph B) should be used. These brackets are secured with 8 x M12 masonry anchors, and can accommodate towers up to 75mm diameter.

The masonry anchors used should be of the pumped resin grout type, and fixings should be subject to a proof load test prior to the bracket installation (photograph ‘C ‘). This testing demonstrates that fixings and masonry are sufficiently strong to absorb the loading produced by the turbine.

Note, any StealthGen mounting tower should be designed to provide a safe working load of 70 kg in a lateral direction at the hub height of the turbine.


Building Mounting
:

StealthGenStealthGenEclectic StealthGen turbines can be successfully mounted off structural walls (typically the gable wall) using the specially designed

bracketry illustrated. Drawing A (and photograph Aa) shows a typical standard duty installation, secured by 4 x M10 masonry anchors, and provides for a maximum free tower length of 2.5 metres. Refer to ‘Standard Bracket Installation’ section.

Where a greater free tower length is required, i.e. up to 4.5 metres, the heavy duty bracket system (see photograph B) should be used. These brackets are secured with 8 x M12 masonry anchors, and can accommodate towers up to 75mm diameter.

The masonry anchors used should be of the pumped resin grout type, and fixings should be subject to a proof load test prior to the bracket installation (photograph ‘C ‘). This testing demonstrates that fixings and masonry are sufficiently strong to absorb the loading produced by the turbine.

StealthGenNote, any StealthGen mounting tower should be designed to provide a safe working load of 70 kg in a lateral direction at the hub height of the turbine.

Troubleshooting

 Points to check if you think there’s a problem

Mechanical checks:

• Spin the blades by hand – they should rotate smoothly and freely with no hard wp534fc25e_05_06spots.

• Listen for any grinding, scraping or rumbling noises – these would indicate failed bearings or contact between rotating parts inside the alternator.

• Note: if the rotor rotates smoothly and silently, but feels stiff (like turning something in glue), refer to the electrical section on short circuits.

• Next, try rotating the D400 around its yaw axis. Again, it should turn smoothly and freely with no hard spots. If the yaw action is stiff or accompanied by undue noise, suspect the yaw bearings or the bush and slip ring assembly (see electrical section below).

• Check that the blades are fitted the right way round, with the concave surface facing forward, i.e. towards the wind.

• Also, establish that the hub is secure on the alternator shaft and that the rotor does not ‘wobble’ due to wear at the hub.

• Finally, check that all fasteners are tight and secure.

Electrical checks:

Very often poor turbine performance is traced to a problem elsewhere in the installation rather than a fault with the wind generator itself.

• First check that both the D400 and the regulator are the correct voltage for the electrical system. Both items have identification labels showing the voltage, typically 12 or 24 volt.

• The most common cause of low outputs is loose or corroded connections in the output cabling. Check and re-make all connections from turbine to battery. Seawater and electricity are not a good combination, and connections deteriorate very quickly when wet.

• Next, check the turbine by measuring its open circuit voltage. Disconnect the unit as close to the turbine as possible. If it is not too difficult, remove the turbine from its tower and measure at the fly lead cables exiting the yaw shaft of the machine itself.

• With a multimeter set to the 20 volt DC range, connect the red positive meter lead to the red output, the black meter lead to the black output, and spin the unit by hand. On a 12 V D400, you should be able to produce 4, 5 or even 6 volts, depending on how hard you spin. If you see voltages in this range, then the D400 is probably OK. If the D400 has an internal fault such as a missing phase in its alternator, then you will not be able to produce more than one or two volts.

• Assuming the output voltage is OK, try rotating the yaw shaft (where the cables exit) whilst continuing to spin the rotor. If the voltage varies or disappears as you rotate the yaw shaft, the brushes and slip rings require cleaning. Equally, if the voltage remains steady, but the yaw shaft is unduly stiff or squeaks when rotated, the brushes and slip rings would benefit from cleaning.

• If the turbine checks out OK on the voltage test, suspect the rest of the installation. Check each wiring connection for corrosion, tightness and security as well as the fuses, fuse holders etc.

• If a regulator bypass switch is incorporated within the installation, check that this is wired in accordance with the diagram contained in the D400 regulator instructions. Note that a similar switch can be used as a braking switch, and the wiring for this is shown on page 12 of the D400 User’s Manual. Ensure that the two uses of a switch have not been confused.

• Note that the ship’s battery monitor is driven by a shunt, which will be mounted close to the batteries. Ensure the D400 is connected to the non-battery side of the shunt. If it is not, then the D400 output will not be seen by the meter.

• Also, the D400 regulator incorporates a charge splitter (i.e has two outputs). If one of these is connected to the service battery bank and one to the cranking battery or windlass battery, it is possible that power from the D400 is flowing to them in preference to the service bank.

Try connecting both regulator positive outputs together and on to the service bank to see if that improves matters.

• Finally, put a dedicated ammeter in the positive line between turbine and regulator. This should read all current from the D400, including any diverted to the regulator dump loads.

Troubleshooting continued – Poor Yaw Action:

Stiffness in yaw; the D400 will not rotate to face the wind – check for any physical obstructions and the action of the yaw shaft. If the yaw shaft does not rotate freely, suspect damaged or corroded yaw bearings, damaged or corroded slip rings/brush assembly or possibly a bent yaw shaft.

Erratic yaw action; the D400 turns off the wind and is unstable – the D400 is normally very stable in yaw. If the turbine appears to ‘hunt around’ its axis, this could be due to turbulence in the airflow. If so, the problem should disappear when the wind changes direction or the yacht is in a different location.

Check that the D400 is properly secured to the mount tower. There should be no undue play between the turbine and the tower. Also, ensure that the tower is vertical and sufficiently rigid. If the tower is too flexible and bends excessively under wind loading, it should be braced or guyed to stiffen it.

Open Circuit; this is a major cause of poor yaw action, indicating that the turbine is not properly connected to the batteries.

– in this open circuit condition, the rotor will over speed and the blades will become uncharacteristically noisy, emitting a whistling noise. The D400 will frequently turn off the wind, rotating through 360 ° on occasion. Check all wiring, looking for poor or broken connections. Also check fuses. If the fault remains, bypass the regulator to rule out regulator malfunction as the cause of the problem.

Intermittent or occasional erratic yaw action – this could be due to an intermittent electrical fault. If you observe turbine output abruptly dropping out and then suddenly returning, this could indicate a poor connection between the brushes and slip rings.

To service, remove the four self-tapping screws that secure the black brush-holder plate. Remove the brush-holder plate, taking care not to displace the brushes or brush springs.

The slip rings and contact faces of the brushes can then be cleaned with a solvent soaked cloth or fine, wet and dry paper.

Squeaking or grating noises audible in yaw – this could be caused by damaged yaw bearings. More typically, it is caused by dirt or corrosion on the slip rings/ brushes.

Remove the brush-plate as above. If noise is still present with the brush-plate clear of the housing, suspect yaw bearings. If the squeak has gone, it confirms the noise emanates from the brush and slip ring assembly. Clean these parts as in the last section. Also, using a fine file, remove any sharp edges from the contact surfaces of the brushes.

On re-assembly, the yaw shaft should rotate silently. If a squeak is still evident, remove the brush plate again and spray the slip rings and brushes with an electrical lubricant (WD40 or similar) or smear a little silver-loaded grease on the slip rings.

Undue mechanically transmitted noise or vibration

Noise or vibration transmitted down the shaft – suspect a loose rotor. Grasp an blade and rock the rotor to check if there is any relative movement between the rotor and the alternator shaft. If play is felt, remove hub parts and re-build, fitting a new hub centre.

Correct fit of nose cone – check that the nose cone is not catching on the alternator housing.

Blade damage – check that the blades are not damaged or chipped. This may put the rotor out of balance. Replace blades as necessary.

Tail bolts – check tail bolts are tight.

Noises from the alternator – rotate the blades slowly and listen at the alternator housing. Grating or scraping noises indicate a fault within the alternator. Refer to your dealer or Eclectic Energy Limited.

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