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| Frenquently Asked Questions |
| About Technique |
About Commercial |
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- About the unit.
1 mile= 1609 m
1 mph = 1 mile per hour = 0.447 m/s ; 1 m/s = 2.24 mph
1 knot = 1853 m/hour =0.51 m/s; 1m/s= 1.94 knots
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How much power will a small wind turbine output?
There are no firm international standard for how small wind turbines are Rated. Most grid connect wind turbines are given a power specification at 10 m/s (meters per second), the equivalent of 22.4 mph or 19.4 knots. In stronger wind speeds, they produce more .
We rate our small wind turbines at the standard of 10 m/s. Same as the industry level. Therefore the real useful specification is how much power will actually be delivered into a battery bank.
In real conditions the wind is rarely constant. So output graphs can only indication of instantaneous power at given wind speeds. The real measure of performance of wind turbine is ¡°accumulated ampere hours¡± over a period of time (such as a day, a month, etc.).
Suppose the average wind speed is 5 m/s one day. The MW-200 delivers 1.5A at 5 m/s, then we
could estimate a daily yield of 24H X 1.5A = 36AH.
However the wind may blow at 10 m/s for 12 hours and be calm for another 12 hours one day, showing 5 m/s as the average that day. The wind turbine performance is quite different then.
The MW-200 delivers 7A at 10 m/s, thus 12H X 7A = 84AH.
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About start-up wind speed.
Start-up wind speed is an important specification of small wind turbine. The MW series use low cogging 3 phase alternators designed specially for the small wind turbines. They can start-up smoothly at 2.4 m/s, and operate more efficiently in the range of 2.7--10 m/s. Also they take advantage of higher wind speeds to produce higher outputs steadily and safely.
- About the protection technology.
The purposes of protection are twofold:
1. Prevention of overrunning of the blade at high wind speeds potentially causing mechanical damage.
2. Prevention of potential overcharging of the battery.
For small wind turbine, there are usually 3 ways of offering protection under strong wind conditions:
1. Furl-tails: This is a mechanism which allows the unit to avoid facing the full strength of the wind. Drawbacks are:
(1)
The mechanical configuration will not work long ¡
(2) It adds too much to the space taken by the unit which would affect people onboard and decrease the mechanical effectiveness of the boat.
2. Electromagnetic protection: Use internal controller to regulate the charge current and battery voltage.
The drawback is that: the power consuming in the stator of the generator can cause the coil overheat.
3. Use charge regulator to control the unload resistor circuit to consume the redundant power when the battery are charged. Thus the blade wheel will not overrun and the battery is also safety in huge wind. Which is we prefer.
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Benefits of Wind/Solar PV Hybrid System.
The combination of solar and wind make the MW series beneficial even in low wind sites. It's deal for those windy days when the sun is at its lowest.
Wind/PV Hybrid System can lower total system cost. In those cloudy-windy days, MW is a low cost solution to ensure your batteries(always Lead-Acid deep cycle batteries ) stay charged.
Wind/PV Hybrid System can make more consistent power supply, Smooth out seasonal weather
fluctuations, reduce ¡°deep-cycling¡± of batteries and extend battery life.
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About the battery.
All deep cycle batteries are rated in amp-hours. An amp-hour is one amp for one hour, or 10 amps for 1/10 of an hour and so forth. It is amps x hours . If you have something that pulls 2 amps, and you use it for 30 minutes, then the amp-hours used would be 2 (amps) x .5 (hours) = 1 AH. The accepted AH rating time period for batteries is the "20 hour rate". This means that a 12 volts Lead-Acid is discharged down to 10.5 volts over a 20 hour period while the total actual amp-hours it supplies is measured.
Battery charging takes place in 3 basic stages: Bulk , Absorption , and Float .
Bulk Charge: The first stage. Current is sent to batteries at the maximum safe rate they will accept until voltage rises to near (80-90%) full charge level. Voltages at this stage typically range from 10.5 volts to 15 volts. There is no "correct" voltage for bulk charging, but there may be limits on the maximum current that the battery and/or wiring can take.
Absorption Charge: The 2nd stage of 3-stage battery charging. Voltage remains constant and current gradually tapers off as internal resistance increases during charging. It is during this stage that the charger puts out maximum voltage. Voltages at this stage are typically around 14.2 to 15.5 volts.
Float Charge: The 3rd stage of 3-stage battery charging. After batteries reach full charge, charging voltage is reduced to a lower level (typically 12.8 to 13.2) to reduce gassing and prolong battery life. This is often referred to as a maintenance or trickle charge, since it's main purpose is to keep an already charged battery from discharging. PWM, or "pulse width modulation" accomplishes the same thing. In PWM, the controller or charger senses tiny voltage drops in the battery and sends very short charging cycles (pulses) to the battery. This may occur several hundred times per minute. It is called "pulse width" because the width of the pulses may vary from a few microseconds to several seconds. Note that for long term float service, such as backup power systems that are seldom discharged, the float voltage should be around 13.02 to 13.20 volts.
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How to choose the battery capacity.
For example, in a street lamp system with 24VDC battery, when a lamp is 24W and work 8hours a day, than it is (24W / 24V) X 8 hours =8 AH per day. We need the battery can keep system working without solar and wind in succession 3 days. So 8AH X 3 = 24 AH. The depth you discharge a battery to before recharging it is the depth of cycle. In a deep cycle battery, the depth of cycle could be 30%. So we can choose a 80 or 100AH battery bank, because 80AH X 30% =24AH.
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I want to test your products before place an order. Could you provide samples and how could I get them?
We can provide charged samples; We don't offer free samples to our customers at the first transaction, we will refund the samples cost to our customers in their future orders. The sample will be sent out only when we received your payment by T/T or by Western Union. As to the samples prices and their Express freight charges. Please contact us in detail or calculate by yourself.
- About price: could I get your pricelist?
Yes, please tell us the product's name(with its Item number)and quantity you are interested in, then we will offer the corresponding price information by e-mail.
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About the shipment: what kind of shipment will you use?
For sample order or trial order, We usually send the products by air. If for bulk order, we suggest you ship by sea.
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About payment: what terms of payment do you use?
We accept T/T for sample order and trial order , L/C at sight for big order or 30% deposit and balance on/before delivery.
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About warranty: how long for warranty? Do you have the service center to repair when broken or damaged?
2 years warrantly for our wind turbine products. Some accessories are half or one year. It depends on different products. We can replace unqualified products/defective products with new good ones on following order after receiving buyer's unqualified products.
You can go to our agent service center to make any replacement or repair work. You can replace the broken part there.
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