HA-6 The Latest Version
Ha-6 up at last
November 2012 stirred me into starting work on HA-6 and it soon became the biggest build to-date.
This as the name might suggest is our sixth attempt (HA-6) and follows a line of dubious turbines.
Although the F&P motor and its 42 separate coils had been reconfigured to 12v 3 phase delta, and new much bigger blades had been carved, with detailed plans drawn in 2009 (Fig 1), I hadn't got round to building HA-6.
This was a different kettle of fish, all was to be built from scratch, no car hubs or bike bits for HA-6. No more going out to the workshop and making what I felt looked right with "Techie" continually reminding me a safety factor of 2 or 3 would be suffice rather than the safety factor of 10 I seemed to prefer. For the first time I was working to a plan courtesy of "Techie" ( Chris ) a plan which had tolerances of 1/100th of a millimetre yes .01mm ! jeepers I normally work to the nearest 1/2" give or take. ( maybe the reason the plans had set on the shelf for 3 years before I started )
Plans which had been simulated on computer, stress points had been calculated yes all sorts of things I never had heard of were calculated.
HF HA-6 3FP what it stands for:
HF : The first letter of our surname and the name of the farm.
HA : The first two letters of our surname
6 : The number of windturbines built to date.
3 : Has a dual meaning, the third 3 phase type generator, and the rated output is 300 watts
FP : Fisher & Paykel, we re-wired a 230 volt F&P stepper motor from a washing machine to create our alternator.
Concept design (performance table)
The concept design for HA6 came from a combination of practical advice and theory from High Piggott's site, engineering dynamics and the power curve from Fisher Paykel (FP) alternator supplier. This research combined with measurements taken from HA5 to gather data on the rpm, wind speed, power, TSR (Tip Speed Ratio) and automatic furling forces led to the predicted performance table and concept design. And with a little bit of luck…the actual measurements in practice will be close to this performance!
The Alternator
The Alternator mounted on Pivot Housing
The alternator was a Fisher & Paykel Smart Drive washing machine motor. The advantages of a Smart Drive motor are very efficient low speed generation, brushless design, easily configured for 12/24 or 48v from its original 230v set up. With no arcing from brushes they tend to run fairly cool.
A Smart Drive running at 48 volts or less in normal use is safe to work with. In an open circuit situation on high rpm they can produce upto 1500 volts and a high enough current to cause electrocution.
I feel Chris should be doing this section as he done most of the work in re-wiring the 42 coils that make up the stator. The rotor consists of 56 magnets that can make it difficult to start wind turbines because of the cogging effect they create. This was taken into consideration in the design of our blades. Re-wiring was another tedious job, involving cutting and then re-wiring 84 x 0.60mm wires which had to have the shellac (lacquer) removed before soldering. The 84 tails from the coils were re-connected in three phase Delta configuration.
The one saving grace was it could be done in the comfort of the house. I'll leave it at that, lets see if Techie comes up with more detail on it. Watch this space!
Aha! Techie appears to have delivered..................
The alternator wiring
The starting point was to choose the alternator and use the power/rpm curve for the alternator to then design the blades. The alternator was actually a three phase star configuration motor which was rewired to a half series half parallel 3 phase delta configuration alternator with 42 poles. This gave us an alternator with the power we wanted at a lower wind speed and RPM
Blade profile design to suit alternator
Some research online and an anemometer on the HA5 tower gave us the average wind speed for our location. (Albeit our site is far to close to obstructions like trees and buildings!). We attempted to design HA6 to be most efficient at this average wind speed. This was done by matching the blade TSR design to the FP alternator power curve. FP also supplied the starting torque required for the alternator (0.65Nm). The blade design was then based on matching the alternator starting torque and power curve. Hugh Piggots tool for calculating the blade cross sectional profile at various stations along the blade was used. Then the carving began...
Geometry for automatic furling
The HA 6 was designed to furl in high wind speeds to control the maximum RPM of the machine. This was calculated based on taking moments around the yawing pivot. The axial force along the blades shaft causes the whole machine to pivot and the furling pivot allows the tail vain to take the turbine out of the wind. This is based on the principles from Hugh Piggott.
Early measurements seem to indicate that we are not too far from plan, but need to be confirmed with actual wind speed measurements (once we find the software!)
How we re-configured
The starting point was to use the Fisher & Paykel three phase motor series-star wired configuration and then choose the best configuration for our application based on the alternator power curve. We chose to rewire the alternator to a half series half parallel configuration as that suited the rpm and power output we wanted from the machine.
Rewiring of the alternator mainly involved the use of wire cutters, soldering iron, blowlamp and a glue gun....with a helping of patience!
Every 7th leg of the 42 on the alternator was cut and joined together in a ring around the inside of the stator to give a total of 6 tails.
The 6 wires are then joined together in pairs to give a delta configuration with three wires that then go into the rectifier. This configuration gave us an alternator which has a low starting torque and the output at low RPM that we wanted.
A Smart Drive running at 48 volts or less in normal use is safe to work with. In an open circuit situation on high rpm they can produce upto 1500 volts and a high enough current to cause electrocution.
I feel Chris should be doing this section as he done most of the work in re-wiring the 42 coils that make up the stator. The rotor consists of 56 magnets that can make it difficult to start wind turbines because of the cogging effect they create. This was taken into consideration in the design of our blades. Re-wiring was another tedious job, involving cutting and then re-wiring 84 x 0.60mm wires which had to have the shellac (lacquer) removed before soldering. The 84 tails from the coils were re-connected in three phase Delta configuration.
The one saving grace was it could be done in the comfort of the house. I'll leave it at that, lets see if Techie comes up with more detail on it. Watch this space!
Aha! Techie appears to have delivered..................
The alternator wiring
The starting point was to choose the alternator and use the power/rpm curve for the alternator to then design the blades. The alternator was actually a three phase star configuration motor which was rewired to a half series half parallel 3 phase delta configuration alternator with 42 poles. This gave us an alternator with the power we wanted at a lower wind speed and RPM
Blade profile design to suit alternator
Some research online and an anemometer on the HA5 tower gave us the average wind speed for our location. (Albeit our site is far to close to obstructions like trees and buildings!). We attempted to design HA6 to be most efficient at this average wind speed. This was done by matching the blade TSR design to the FP alternator power curve. FP also supplied the starting torque required for the alternator (0.65Nm). The blade design was then based on matching the alternator starting torque and power curve. Hugh Piggots tool for calculating the blade cross sectional profile at various stations along the blade was used. Then the carving began...
Geometry for automatic furling
The HA 6 was designed to furl in high wind speeds to control the maximum RPM of the machine. This was calculated based on taking moments around the yawing pivot. The axial force along the blades shaft causes the whole machine to pivot and the furling pivot allows the tail vain to take the turbine out of the wind. This is based on the principles from Hugh Piggott.
Early measurements seem to indicate that we are not too far from plan, but need to be confirmed with actual wind speed measurements (once we find the software!)
How we re-configured
The starting point was to use the Fisher & Paykel three phase motor series-star wired configuration and then choose the best configuration for our application based on the alternator power curve. We chose to rewire the alternator to a half series half parallel configuration as that suited the rpm and power output we wanted from the machine.
Rewiring of the alternator mainly involved the use of wire cutters, soldering iron, blowlamp and a glue gun....with a helping of patience!
Every 7th leg of the 42 on the alternator was cut and joined together in a ring around the inside of the stator to give a total of 6 tails.
The 6 wires are then joined together in pairs to give a delta configuration with three wires that then go into the rectifier. This configuration gave us an alternator which has a low starting torque and the output at low RPM that we wanted.
Blades
The Blade hub showing the keyway
Like all the blades since HA-4 they are hand-carved from 8" x 2" timber with a diameter of 8' 2" (2.5 meters). At one end 2 x pieces of 8x2 are glued and dowelled together to give us 8x4 the thickness necessary to get the " Twist " at the centre of the blades. A sleeve was turned to fit the rotor shaft, with a slot to accommodate a woodruff key and welded to a 10" dia. 5mm thick back plate. 3 x 12 mm bolts were welded to the back plate to sandwich the blades between it and the front plate. A hole was drilled through the front and rear plywood discs and the blade inner ends to allow them to mount on the rotor sleeve/back plate assembly. Holes were drilled in the back plate at this time to locate the rotor housing on to the blades in final assembly.
On previous models timber was probably the biggest cost involved but not this time, Both the Blades and the Plywood Tail had set for almost 3 years, so were well dried out not to mention matured, and were given 3 coats of Ronseal Black 5 year preservative. Hope it does what it says on the tin. I won't go into detail on blade carving as there are plenty of sites that deal with it.
Finally the blades were balanced, a tedious job which is absolutely essential. I simply use lead weights screwed to the back side of the blades, a remedy that has proved successful in the past. Its always best to balance blades without the rotor/magnets attached as " cogging " on the generator distorts blade free movement.
To date i'm very happy with the blades they really are a beautiful shape and are starting in winds of less than 10mph.
On previous models timber was probably the biggest cost involved but not this time, Both the Blades and the Plywood Tail had set for almost 3 years, so were well dried out not to mention matured, and were given 3 coats of Ronseal Black 5 year preservative. Hope it does what it says on the tin. I won't go into detail on blade carving as there are plenty of sites that deal with it.
Finally the blades were balanced, a tedious job which is absolutely essential. I simply use lead weights screwed to the back side of the blades, a remedy that has proved successful in the past. Its always best to balance blades without the rotor/magnets attached as " cogging " on the generator distorts blade free movement.
To date i'm very happy with the blades they really are a beautiful shape and are starting in winds of less than 10mph.
Pivot Housing
The Pivot Housing rear view
With the pole at the top of the tower being 60mm dia. with a 4mm wall it was decided to sleeve it with a short section of 50mm dia 8mm wall tubing and use a piece of 60x4mm tubing for the furling bearing welded to a 6mm flat steel plate to carry the generator shaft (Pivot housing),tail pivot, manual furling guide pipe (which "Techie" had overlooked in the plans), stator, 3 phase connections and cable anchorages. Somewhere around this time the plans with their 1/100th of a millimetre tolerances got mislaid for a while. The furling pipe was drilled and tapped to accommodate grease nipples and a nylon bush was turned on the lathe to fit on top of 50x8mm pole under the 6mm plate to avoid wear when yawing, time will tell how this actually lasts. A key was welded on the side of pivot housing to keep gyro from rotating ( see images of completed Windturbine). Several fillet pieces, the back bearing mounting, furling pipe support and the tail pivot support were cut and welded in place creating what I call the Pivot Housing ( see image opposite ). The tail pivot offset to the centre of the tower is 100mm and you can plainly see the centre of the blades is offset in the front view of the Wind turbine in images.
Tail
Tail with manual furling cable attached
The tail is similar in construction to HA-5 except this time the horizontal pipe was attached to the top of the Tail Pivot with a fillet underneath for support see HA-4 for comparison, there was no specific reason for this I thought it was tidier looking. The vertical braces were checked into the tail pipe to leave a clean flat surface for the Plywood Tail vane. Again the Tail Pivot was tapped and fitted with a grease nipple. Welding is critical on the Tail as this component suffers a lot of vibration. My preferred choice of pipe is 25 x 3 mm wall steel and it had served well on HA-5. A notch was cut in the tail pivot that lines up with the Tail Pivot base on the Pivot housing (see Tail Pivot image above) to control the amount of movement of the tail ( Over furl and the tail could hit the blades) it also holds the tail at approx 105 degrees to the blades to help improve starting.
Manual Furling Mechanism
Home made Gyro at last
To enable us to close down the wind turbine in extreme weather conditions a Gyro type mechanism was designed and made. A collar was turned and welded to the top of the 60mm pole protruding from the tower where it joined the 50mm section. Two 15mm dia rods were welded to it to locate in the 19mm holes in the gyro.
The centre core of the Gyro was cut open on one side to form a keyway and prevent it rotating on the Pivot Housing. Once the centre core was fitted to the Pivot housing lugs were made to retain the nylon bush in it and secured to it with allen keys. A thrust collar was welded to these two lugs and the cable anchorage to keep the FREE to rotate collar in place. I Hope to make a drawing of the Gyro which I will post to the images page. The Gyro had been made in my old way built first and now I have to make a drawing of it. There are several pictures of the Gyro on the "Images" page which hopefully will help explain how it works, a bit like the rotor/gyro system on BMX bikes.
When the linkage is pulled the Gyro body is pulled down the Pivot Housing which in turn pulls a cable that causes the tail to furl and puts the turbine out of the wind. This can be done no matter what direction the turbine is pointing in and irrespective of whether it is Yawing or not. Since the Runaway of HA-4 we have incorporated a manual furling device which is used if winds of over 40mph are forecast.
The centre core of the Gyro was cut open on one side to form a keyway and prevent it rotating on the Pivot Housing. Once the centre core was fitted to the Pivot housing lugs were made to retain the nylon bush in it and secured to it with allen keys. A thrust collar was welded to these two lugs and the cable anchorage to keep the FREE to rotate collar in place. I Hope to make a drawing of the Gyro which I will post to the images page. The Gyro had been made in my old way built first and now I have to make a drawing of it. There are several pictures of the Gyro on the "Images" page which hopefully will help explain how it works, a bit like the rotor/gyro system on BMX bikes.
When the linkage is pulled the Gyro body is pulled down the Pivot Housing which in turn pulls a cable that causes the tail to furl and puts the turbine out of the wind. This can be done no matter what direction the turbine is pointing in and irrespective of whether it is Yawing or not. Since the Runaway of HA-4 we have incorporated a manual furling device which is used if winds of over 40mph are forecast.
Alternator Cowling
Main Generator Cover
The cowling was fabricated from two sheep lick buckets. One for the main section and the bottom of the second one to make the back of the cowling. Holes were first reinforced and then drilled. Although the cowling was easy to work with a lot of time was spent on the supporting brackets to ensure it didn't foul on the Rotor. The cowling runs in the recess on the front side of the rotor to try to prevent water ingress. I designed the cowling that it could be removed with blades in place for ease of servicing. Cowling and Rotor casing were painted to prevent UV damage to the plastic making it brittle as well as for cosmetic reasons.
The Base
Reinforced base being made for burying in concrete
A one cubic meter hole was dug (see Images page) steel bars were driven sideways under existing surrounding concrete and the wire base cage opposite was lowered into the hole and leveled. As the concrete was poured into the hole more reinforcing rods were layered in a crisscross pattern. Once the concrete was set a "T" shaped channel iron base was made and bolted to the three existing tower legs. The "T" shaped base was welded to a solid bar to form a hinge to allow the tower to tilt for servicing. A total of eleven bolts secure the tower to the concrete, with two plates locking down the hinge rather than depend on the hinge holding it. The mounting blocks were drilled tapped and grease nipples fitted to facilitate lubrication.
The Tower
The Tower Waiting for HA-6 to arrive
The same tower was used for HA-6 as HA-5 with the addition of a linkage to activate the manual furling mechanism ( the linkage can clearly be seen in other pictures on the "Images" page. The tower which is constructed from 25mm solid bar with 15mm solid steel bracing was mounted on a hinged channel iron base. This allows the tower to be tilted for servicing see video. Eleven bolts were welded to reinforcing rod and were buried in a base of 1 cu, meter of concrete. Further images can be seen on "Images" page. The pole carrying the alternator locates in two collars on the tower. Pole is then secured by 6 bolts in the collars.
Electrical Connection
Water Proof plug
I used a 30 amp junction box on the pivot housing to join the 6 wires from the 3 phases on the stator to a 3 core wire which was folded over and clamped to the Pivot Housing to prevent the cable connection being pulled out by accident. We have never found Slip Rings necessary on any of our wind turbines, we simply allow the wire to hang free down the centre of the tower. On HA-6 I decided to fit a water proof plug and socket at the bottom of tower to facilitate tilting. Prior to this the cable had to be disconnected from the cabinet inside the building. I used one of the round plugs similar to what is used on caravan sites etc. It would appear in our experience that the wind turbine rotates clockwise and anti-clockwise in roughly equal amounts and the cable dosn't get its self wound up in knots.
How its all connected. this section is still under construction apologies for errors spelling mistakes etc. Please call back later
I decided to make a new cabinet for the control panel from scratch. Only voltage in cabinet is 12 volt with 230v inverter mounted outside cabinet. Please note the drawing below was created on Microsoft Paint and while the connections should be accurate the size of wire is not always as accurate as could be.
Our main power comes from the 3 phase turbine who's output at 12 volts AC enters the cabinet and goes into a 50 amp air cooled bridge rectifier before going through a separate ammeter to join the bus bars.
Power also comes from 3 solar panels which are wired in parallel they enter the cabinet and are fused separately before going through a schottky blocking diode, ammeter and switch before entering the bus bars. I damaged a few early circuits by disconnecting batteries without isolating Solar panels allowing peak voltages hence the switch. Output from the Solar panels is not good as they were are all damaged when I acquired them.
Power is stored in 14x 2 volt 400ah batteries. Batteries are wired in series in 2 banks of 6 with a "spare" 2v cell wired in parallel. The two strings of seven batteries are then joined in parallel to give us a theoretical storage of 11kw at 12 volts. Obviously its not possible to use all the stored power without damage to the battery bank. We estimate 4-5kw should be available more than enough for our lighting requirements.
A switched volt meter is attached across the positive and negative bus bars to indicate a system voltage. A further digital ammeter with shunt and volt meter have also been added to the output circuit before entering the 230v inverter. We wanted to see what the inverter was consuming in addition to the load. As it happens it uses less than 1/10 of an amp the smallest measurement on the digital ammeter. Having said that I also use 12v LED PIR Flood lights directly from the bus bar via separate fuses.
A 33,000uF 16v aluminum capacitor is connected across the positive and negative bus bars to help even out the turbine peaks and raise the charging voltage.
A 12v timer and relay supply the inverter with fuses attached. There is a further override switch which bypasses the timer circuit. The reason for the timer is to try and extend the life of the inverter as its only powered up at times its required rather than running 24/7.
Our latest acquisition is a Morningstar Tristar 45 and it is used to divert excess power to a dump load. The dump load is a 12v 3 element water heater which I intend to wire and fuse on three separate circuits so failure of one circuit will still leave some dump load capacity. The unused terminals on the Tristar are for a battery temperature sensor which I opted not to install.
I use the Tristar regulator as Diversion Charge Control ie. when voltage reaches a preset level the access power is diverted to the water heater element.
This protects the Inverter, Timer and Batteries from spikes in the voltage and consequent damage to them. It has been mounted externally on the cabinet front to allow air flow over its cooling fins. You never know we might have warm water to wash our hands at lambing time!
Earth connections to Solar Panels, Wind Turbine Tower and Tristar regulator are made in corner of cabinet and grounded.
Bypass switch for the timer and circuits for the 12v LED lighting have been omitted from the Control Panel Diagram to avoid complicating the diagram.
Our main power comes from the 3 phase turbine who's output at 12 volts AC enters the cabinet and goes into a 50 amp air cooled bridge rectifier before going through a separate ammeter to join the bus bars.
Power also comes from 3 solar panels which are wired in parallel they enter the cabinet and are fused separately before going through a schottky blocking diode, ammeter and switch before entering the bus bars. I damaged a few early circuits by disconnecting batteries without isolating Solar panels allowing peak voltages hence the switch. Output from the Solar panels is not good as they were are all damaged when I acquired them.
Power is stored in 14x 2 volt 400ah batteries. Batteries are wired in series in 2 banks of 6 with a "spare" 2v cell wired in parallel. The two strings of seven batteries are then joined in parallel to give us a theoretical storage of 11kw at 12 volts. Obviously its not possible to use all the stored power without damage to the battery bank. We estimate 4-5kw should be available more than enough for our lighting requirements.
A switched volt meter is attached across the positive and negative bus bars to indicate a system voltage. A further digital ammeter with shunt and volt meter have also been added to the output circuit before entering the 230v inverter. We wanted to see what the inverter was consuming in addition to the load. As it happens it uses less than 1/10 of an amp the smallest measurement on the digital ammeter. Having said that I also use 12v LED PIR Flood lights directly from the bus bar via separate fuses.
A 33,000uF 16v aluminum capacitor is connected across the positive and negative bus bars to help even out the turbine peaks and raise the charging voltage.
A 12v timer and relay supply the inverter with fuses attached. There is a further override switch which bypasses the timer circuit. The reason for the timer is to try and extend the life of the inverter as its only powered up at times its required rather than running 24/7.
Our latest acquisition is a Morningstar Tristar 45 and it is used to divert excess power to a dump load. The dump load is a 12v 3 element water heater which I intend to wire and fuse on three separate circuits so failure of one circuit will still leave some dump load capacity. The unused terminals on the Tristar are for a battery temperature sensor which I opted not to install.
I use the Tristar regulator as Diversion Charge Control ie. when voltage reaches a preset level the access power is diverted to the water heater element.
This protects the Inverter, Timer and Batteries from spikes in the voltage and consequent damage to them. It has been mounted externally on the cabinet front to allow air flow over its cooling fins. You never know we might have warm water to wash our hands at lambing time!
Earth connections to Solar Panels, Wind Turbine Tower and Tristar regulator are made in corner of cabinet and grounded.
Bypass switch for the timer and circuits for the 12v LED lighting have been omitted from the Control Panel Diagram to avoid complicating the diagram.
Simplified schematic for charging circuit see below
Revised Control Diagram work in progress see latest news for updates
In Conclusion
HF HA-6 3FP
Rated at 328 watts in a 10 m/s wind this machine is capable of 6 times the power of any previous turbines. It has to be said it was a long time coming not to mention the most difficult build and it has now created new problems disposing of excess power. When we get a controller in place I will update this section. Costs are still on going and will also be listed later.