vertical 7 copies

8/2/2019 Vertical 7 Copies

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Energy from the road

side


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To feed in electric energy the signalization of Highways one produces

electricity with wind but it's the wind produce by the displacement of

cars and trucks, for example a small truck at 70 mph produces a

speed wind of 30 mph. To exploit this kind of wind one must a vertical

axis wind turbine near the road, the natural wind give energy too. The

idea is: Have an self energy-feed unit for all signalization system of

highway, to save energy and money


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In this project we show that how we generate a valuable voltage with the

help of moving traffic on the road. In this project we use conversion of

mechanical energy into electrical energy. For this purpose we install one

vertical axix wind mill on the road. On all the wind mill we use dynamo

to generate a voltage. When wind rotate then dynamo also rotate and

generate the voltage With the help of this dynamo we convert the

mechanical energy into electrical energy. We use dc dynamo, so output from

the dynamo is connected to the dc battery. When battery is fully charged

then we use battery for our project.

We install one photoelectric effect in the project. Street light is to be switch

on automatically in the night and lights are automatically off in the day

night.

In this project we switch on the street light in night in half mode. Half mode

means all the lights are to be on in 50 percent on/off mode. Rest of lights are

to be on if the traffic is on the road. If the road is with traffic then all the

lights are on. If the road is without traffic then 50 percent lights are again

off.

For road sensing, we use two pair of infra red sensor on the road. When any

car cross the road then infra red beam is interrupted and signal is connected


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to the controller. Controller sense the signal and increment the counter.

Counter display the total number of vehicle on road. When counter shows a

0 number then road lights are off to 50 percent.

In circuit we use LDR as a light dependent resistor to sense the darkness.

When LDR is in dark then LDR offer a low resistance. At this time LDR

gives a signal to the circuit to switch on/off the road light for 50 percent. As

the LDR is in dark then 50 percent is on. But if the traffic is on the road

then road sensor gets a signal and connect to the circuit. In the road sensor

we use infra red l.e.d and photodiode as a road sensor. When any vehicle

interrupt the infra red light then circuit sense the interruption and at this

time Or comparator circuit switch on the light. In this project we use LM

358 as a comparator with infra red sensors.


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To feed in electric energy the signalization of Highways one produces

electricity with wind but it's the wind produce by the displacement of

cars and trucks, for example a small truck at 70 mph produces a

speed wind of 30 mph. To exploit this kind of wind one must a vertical

axis wind turbine near the road, the natural wind give energy too. The

idea is: Have an self energy-feed unit for all signalization system of

highway, to save energy and money

In the night lights are automatic on with the help of photovoltaic switch

logic.

But all lights are not on, only half light are on. Other half lights switch on

automatically when any vehicle move on the bridge, when there is no

vehicle on the bridge then lights are off automatically.

We use two infra red sensors to check the movement of vehicle. When first

infra red sensor is on then lights are on and when second sensor is interrupt

then lights are off.


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COMPONENTS USED:

89S51 MICROCONTROLLER.

PHOTODIODE( 2)5MM

INFRA RED LED (2) 5MM

7805 REGULATOR ( 5 VOLT)

CRYSTAL ( 12 MHZ) CONNECTED TO PIN NO 18 AND 19

27 PF ( 2_) GROUNDED FROM CRYSTAL

RESISTANCE:

10K OHM (3)

470 OHM(2)

270 OHM (6)

1 K OHM (1)

LDR FOR AUTOMATIC STREET LIGHT

NPN BC 548 FOR LDR SWITCHING

GENERAL PURPOSE PCB

12 VOLT DYANMO


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6 VOLT CHARGEBALE BATTERY

CHANGOVER SWITCH

L.E.D ( 6 ) FOR STREET LIGHT

MAIN THEME OF THIS PROJECT

NON CONVENTIONAL ENERGY GENERATION

CONCEPT:

MECHANICAL TO ELECTRICAL ENERGY

LOGIC: USE DYANMO AS A SPEED BRAKER , One rod with the

dynamo is placed like a speed braker. Dyanmo is so powerful. Movement of

vehicle just rotate the dynamo shaft and electricity is generated. This

voltage is to be stored in the chargeable battery.

In the night lights are automatic on with the help of photovoltaic switch

logic.

But all lights are not on, only half light are on. Other half lights switch on

automatically when any vehicle move on the bridge, when there is no

vehicle on the bridge then lights are off automatically.


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In this project we use 89s51 controller , family member of the 8051 family..

supply voltage of the microcontroller is 5 volt dc . for this prupose we

convert the battery voltage into 5 volt dc with the help of the 5 volt regulator

circuit. For this purpose we use ic 7805 regulator to regulate the high

voltage inot 5 volt dc. One capacitor is ground from the regulator for

filteration . Capcitor reduce the noise . Output of the regulator is connected

to the pin no 40 of the controller directly. One crystal is connected to the pin

no 18 and 19 of the controller to provide a oscillation signal. For this

purpose we use 12 Mhz crystal. Two capacitor are grounded from the crystal

to reduce the noise In this project we use two logic. One is light sensitive

logic and second is road sensor logic. When sensor is in dark then all the

lights are on and when sensor is in light then all the lights are off. This is

done by the light sensor ( LDR). LDR is a light dependent resistor , when

light fall on the ldr then ldr offers a low resistance and when ldr is in dark

then ldr offeres a high resistance. Here in this project we use the ldr with npn

transistor circuit. Emitter of the npn transistor is connected to the ground

and collector is connected to the pin no 3 of the controller.


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when ldr is in light then there is low positive on the base of the npn

transistor and collector is become more negative. When ldr is in dark then

there is no base voltage and hence collector become more positive.

Microcontroler sense this change of voltage and switch on the output led

whish is connected to the port 0,

Out put leds are connected with the port 0 through the resistance in series,

here in this we use 6 l.e.d . Common point of the l.e.d is connected with the

positive line. Out of 6 only three l.e.ds are on .

Our second part of this project is infra red sensor. In this logic when any car

cross the first ir sensor then all the led are on and if the traffic continuous

then led are on if the no car on the road then again three led are eon and

three are off

For this purpose we use two IR sensor circuit with this project.


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here in this project we use infra red sensor and one photodiode circuit when

light fall on the photosensor then resistance of photos sensor become low

and hence negative voltage is applied to the controller, when any car cross

the photodiode and then photo diode resistance become high and hence

signal is change on the pin no 2 of the controller. As the controller sense

this change of signal on pin then all the light are on .


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Main program is written in the 8051 ide siftware. We wrote the software in

the assembly language. In the 8051 ide software


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Once the software is complete and there is no error then we transfer this

hex code into the blank ic with the help of the serial port programmer circuit.


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Basic of the microcontroller.

PROJECT DESCRIPTION

MICROCONTROLLER AT89C51

Architecture of 8051 family:-

The figure 1 above shows the basic architecture of 8051 family of

microcontroller.

Features Compatible with MCS-51 Products

4K Bytes of In-System Reprogrammable Flash Memory

Endurance: 1,000 Write/Erase Cycles

Fully Static Operation: 0 Hz to 24 MHz

Three-Level Program Memory Lock

128 x 8-Bit Internal RAM

32 Programmable I/O Lines

Two 16-Bit Timer/Counters

Six Interrupt Sources


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Programmable Serial Channel

Low Power Idle and Power Down Modes

Description

The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K

bytes of Flash Programmable and Erasable Read Only Memory (PEROM). The device is

manufactured using Atmels high density nonvolatile memory technology and is

compatible with the industry standard MCS-51 instruction set and pinout. The on-chip

Flash allows the program memory to be reprogrammed in-system or by a conventional

nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a

monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a

highly flexible and cost effective solution to many embedded control applications. The

AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM,

32 I/O lines, two 16-bit timer/counters, five vector two-level interrupt architecture, a full

duplex serial port, and on-chip oscillator and clock circuitry.

In addition, the AT89C51 is designed with static logic for operation down to zero

frequency and supports two software selectable power saving modes. The Idle Mode stops

the CPU while allowing the RAM, timer/counters, serial port and interrupt system to

continue functioning. The Power down Mode saves the RAM contents but freezes the

oscillator disabling all other chip functions until the next hardware reset.

Pin Description

VCC

Supply voltage.

GND

Ground.

Port 0

Port 0 is an 8-bit open drain bidirectional I/O port. As an output port each pin can sink

eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high

impedance inputs. Port 0 may also be configured to be the multiplexed low order

address/data bus during accesses to external program and data memory. In this mode P0


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has internal pull-ups. Port 0 also receives the code bytes during Flash programming, and

outputs the code bytes during program verification.

External pull-ups are required during program verification.


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Port 1

Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output buffers can

sink/source four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the

internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being

pulled low will source current (IIL) because of the internal pull-ups. Port 1 also receives

the low-order address bytes during Flash programming and verification.

Port 2




pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-

order address byte during fetches from external program memory and during accesses to

external data memory that uses 16-bit addresses (MOVX @ DPTR). In this application it

uses strong internal pull-ups when emitting 1s. During accesses to external data memory

that uses 8-bit addresses (MOVX @ RI); Port 2 emits the contents of the P2 Special

Function Register. Port 2 also receives the high-order address bits and some control signals

during Flash programming and verification.

Port 3




pulled low will source current (IIL) because of the pull-ups. Port 3 also serves the functions

of various special features of the AT89C51 as listed below:

Port 3 also receives some control signals for Flash programming and verification.

RST

Reset input. A high on this pin for two machine cycles while the oscillator is running resets

the device.


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ALE/PROG

Address Latch Enable output pulse for latching the low byte of the address during accesses

to external memory. This pin is also the program pulse input (PROG) during Flash

programming. In normal operation ALE is emitted at a constant rate of 1/6 the oscillator

frequency, and may be used for external timing or clocking purposes. Note, however, that

one ALE pulse is skipped during each access to external Data Memory. If desired, ALE

operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is

active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled

high. Setting the ALE-disable bit has no effect if the microcontroller is in external

execution mode.

PSEN

Program Store Enable is the read strobe to external program memory.

Port Pin Alternate Functions

P3.0 RXD (serial input port)

P3.1 TXD (serial output port)

P3.2 INT0 (external interrupt 0)

P3.3 INT1 (external interrupt 1)

P3.4 T0 (timer 0 external input)

P3.5 T1 (timer 1 external input)

P3.6 WR (external data memory write strobe)

P3.7 RD (external data memory read strobe)

When the AT89C51 is executing code from external program memory, PSEN is activated

twice each machine cycle, except that two PSEN activations are skipped during each access

to external data memory.

EA/VPP


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External Access Enable. EA must be strapped to GND in order to enable the device to fetch

code from external program memory locations starting at 0000H up to FFFFH. Note,

however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA

should be strapped to VCC for internal program executions. This pin also receives the 12-

volt programming enable voltage (VPP) during Flash programming, for parts that require

12-volt VPP.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

Oscillator Characteristics

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which

can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz

crystal or ceramic resonator may be used. To drive the device from an external clock

source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure

2.There are no requirements on the duty cycle of the external clock signal, since the input

to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and

maximum voltage high and low time specifications must be observed.


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Idle Mode

In idle mode, the CPU puts itself to sleep while all the on chip peripherals remain active.

The mode is invoked by software. The content of the on-chip RAM and all the special

functions registers remain unchanged during this mode. The idle mode can be terminated

by any enabled

Interrupt or by hardware reset. It should be noted that when idle is terminated by a hard

Hardware reset, the device normally resumes program execution, from where it left off, up

to two machine cycles before the internal reset algorithm takes control. On-chip hardware

inhibits access to internal RAM in this event, but access to the port pins is not inhibited. To

eliminate the possibility of an unexpected write to a port pin when Idle is terminated by

reset, the instruction following the one that invokes Idle should not be one that writes to a

port pin or to external memory.


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Status of External Pins during Idle and Power down Modes

Mode Program Memory ALE PSEN PORT0 PORT1 PORT2 PORT3

Idle Internal 1 Data

Idle External 1 Float Data Address Data

Power down Internal 0 Data

Power down External 0 Float Data

Power down Mode

In the power down mode the oscillator is stopped, and the instruction that invokes power

down is the last instruction executed. The on-chip RAM and Special Function Registers

retain their values until the power down mode is terminated. The only exit from power

down is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM.

The reset should not be activated before VCC is restored to its normal operating level and

must be held active long enough to allow the oscillator to restart and stabilize.

Program Memory Lock Bits

On the chip are three lock bits which can be left un-programmed (U) or can be

programmed (P) to obtain the additional features listed in the table below:

When lock bit 1 is programmed, the logic level at the EA pin is sampled and latched during

reset. If the device is powered up without a reset, the latch initializes to a random value,

and holds that value until reset is activated. It is necessary that the latched value of EA be

in agreement with

The current logic level at that pin in order for the device to function properly.

Lock Bit Protection Modes

Program Lock Bits Protection Type

LB1 LB2 LB3

1 U No program lock features.

2 P U MOVC instructions executed from external program memory are disabled from

fetching code


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Bytes from internal memory, EA is sampled and latched on reset, and further programming

of the

Flash is disabled.

3 P U Same as mode 2, also verify is disabled.

4 P same as mode 3, also external execution is disabled.

Programming the Flash

The AT89C51 is normally shipped with the on-chip Flash memory array in the erased state

(that is, contents = FFH) and ready to be programmed. The programming interface accepts

either a high-voltage (12-volt) or a low-voltage (VCC) program enable signal. The low

voltage programming mode provides a convenient way to program the AT89C51 inside the

users system, while the high-voltage programming mode is compatible with conventional

third party Flash or EPROM programmers. The AT89C51 is shipped with either the high-

voltage or low-voltage programming mode enabled. The respective top-side marking and

device signature codes are listed in the following table. The AT89C51 code memory array

is programmed byte-by byte

In either programming mode. To program any nonblank byte in the on-chip Flash Memory,

the entire memory must be erased using the Chip Erase Mode.

Programming Algorithm:

Before programming the AT89C51, the address, data and control signals should be set up

according to the Flash programming mode table and Figures 3 and 4. To program the

AT89C51, take the following steps.

1. Input the desired memory location on the address lines.

2. Input the appropriate data byte on the data lines.

3. Activate the correct combination of control signals.

4. Raise EA/VPP to 12V for the high-voltage programming mode.

5. Pulse ALE/PROG once to program a byte in the Flash array or the lock bits. The byte-

write cycle is self-timed and typically takes no more than 1.5 ms. Repeat steps 1 through 5,

changing the address and data for the entire array or until the end of the object file is

reached.


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Data Polling:

The AT89C51 features Data Polling to indicate the end of a write cycle. During a write

cycle, an attempted read of the last byte written will result in the complement of the written

datum on PO.7. Once the write cycle has been completed, true data are valid on all outputs,

and the next cycle may begin. Data Polling may begin any time after a write cycle has been

initiated.

Ready/Busy:

The progress of byte programming can also be monitored by the RDY/BSY output signal.

P3.4 is pulled low after ALE goes high during programming to indicate BUSY. P3.4 is

pulled high again when programming is done to indicate READY.

Program Verify:

If lock bits LB1 and LB2 have not been programmed, the programmed code data can be

read back via the address and data lines for verification. The lock bits cannot be verified

directly. Verification of the lock bits is achieved by observing that their features are

enabled.

Chip Erase:

The entire Flash array is erased electrically by using the proper combination of control

signals and by holding ALE/PROG low for 10 ms. The code array is written with all 1s.

The chip erase operation must be executed before the code memory can be re-programmed.

Reading the Signature Bytes:

The signature bytes are read by the same procedure as a normal verification of locations

030H,

031H, and 032H, except that P3.6 and P3.7 must be pulled to a logic low. The values

returned are as follows.

(030H) = 1EH indicates manufactured by Atmel

(031H) = 51H indicates 89C51


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(032H) = FFH indicates 12V programming

(032H) = 05H indicates 5V programming

Programming Interface

Every code byte in the Flash array can be written and the entire array can be erased by

using the appropriate combination of control signals. The write operation cycle is self

timed and once initiated, will automatically time itself to completion. All major

programming vendors offer worldwide support for the Atmel microcontroller series. Please

contact your local programming vendor for the appropriate software revision.

Flash Programming Modes

Note: 1. Chip Erase requires a 10-ms PROG pulse.

SPECIAL FUNCTION REGISTER (SFR) ADDRESSES:

ACC ACCUMULATOR 0E0H

B B REGISTER 0F0H

PSW PROGRAM STATUS WORD 0D0H

SP STACK POINTER 81H

DPTR DATA POINTER 2 BYTESDPL LOW BYTE OF DPTR 82H

DPH HIGH BYTE OF DPTR 83H

P0 PORT0 80H

P1 PORT1 90H

P2 PORT2 0A0H

P3 PORT3 0B0H

TMOD TIMER/COUNTER MODE CONTROL 89H

TCON TIMER COUNTER CONTROL 88H

TH0 TIMER 0 HIGH BYTE 8CH

TLO TIMER 0 LOW BYTE 8AH

TH1 TIMER 1 HIGH BYTE 8DH

TL1 TIMER 1 LOW BYTE 8BH


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SCON SERIAL CONTROL 98H

SBUF SERIAL DATA BUFFER 99H

PCON POWER CONTROL 87H

TMOD (TIMER MODE) REGISTER

Both timers are the 89c51 share the one register TMOD. 4 LSB bit for the timer 0 and 4

MSB for the timer 1.In each case lower 2 bits set the mode of the timer

Upper two bits set the operations.

GATE: Gating control when set. Timer/counter is enabled only while the INTX pin

is high and the TRx control pin is set. When cleared, the timer is enabled whenever the

TRx control bit is set

C/T: Timer or counter selected cleared for timer operation (input from internal

system clock)

M1 Mode bit 1

M0 Mode bit 0

M1 M0 MODE OPERATING MODE

0 0 0 13 BIT TIMER/MODE

0 1 1 16 BIT TIMER MODE

1 0 2 8 BIT AUTO RELOAD

1 1 3 SPLIT TIMER MODE

PSW (PROGRAM STATUS WORD)


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CY PSW.7 CARRY FLAG

AC PSW.6 AUXILIARY CARRY

F0 PSW.5 AVAILABLE FOR THE USER FRO GENERAL PURPOSE

RS1 PSW.4 REGISTER BANK SELECTOR BIT 1

RS0 PSW.3 REGISTER BANK SELECTOR BIT 0

0V PSW.2 OVERFLOW FLAG

-- PSW.1 USER DEFINABLE BIT

P PSW.0 PARITY FLAG SET/CLEARED BY HARDWARE

PCON REGISATER (NON BIT ADDRESSABLE)

If the SMOD = 0 (DEFAULT ON RESET)

TH1 = CRYSTAL FREQUENCY

256---- ____________________

384 X BAUD RATE

If the SMOD IS = 1

CRYSTAL FREQUENCY

TH1 = 256--------------------------------------

192 X BAUD RATE

There are two ways to increase the baud rate of data transfer in the 8051

1. To use a higher frequency crystal

2. To change a bit in the PCON register

PCON register is an 8 bit register. Of the 8 bits, some are unused, and some are used for the

power control capability of the 8051. The bit which is used for the serial communication is


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D7, the SMOD bit. When the 8051 is powered up, D7 (SMOD BIT) OF PCON register is

zero. We can set it to high by software and thereby double the baud rate

BAUD RATE COMPARISION FOR SMOD = 0 AND SMOD =1

TH1 (DECIMAL) HEX SMOD =0 SMOD =1

-3 FD 9600 19200

-6 FA 4800 9600

-12 F4 2400 4800

-24 E8 1200 2400

XTAL = 11.0592 MHZ

IE (INTERRUPT ENABLE REGISTOR)

EA IE.7 Disable all interrupts if EA = 0, no interrupts is acknowledged

If EA is 1, each interrupt source is individually enabled or disabled

By sending or clearing its enable bit.

IE.6 NOT implemented

ET2 IE.5 enables or disables timer 2 overflag in 89c52 only

ES IE.4 Enables or disables all serial interrupt

ET1 IE.3 Enables or Disables timer 1 overflow interruptEX1 IE.2 Enables or disables external interrupt

ET0 IE.1 Enables or Disables timer 0 interrupt.

EX0 IE.0 Enables or Disables external interrupt 0

INTERRUPT PRIORITY REGISTER

If the bit is 0, the corresponding interrupt has a lower priority and if the bit is 1 thecorresponding interrupt has a higher priority

IP.7 NOT IMPLEMENTED, RESERVED FOR FUTURE USE.

IP.6 NOT IMPLEMENTED, RESERVED FOR FUTURE USE

PT2 IP.5 DEFINE THE TIMER 2 INTERRUPT PRIORITY LELVEL

PS IP.4 DEFINES THE SERIAL PORT INTERRUPT PRIORITY LEVEL


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PT1 IP.3 DEFINES THE TIMER 1 INTERRUPT PRIORITY LEVEL

PX1 IP.2 DEFINES EXTERNAL INTERRUPT 1 PRIORITY LEVEL

PT0 IP.1 DEFINES THE TIMER 0 INTERRUPT PRIORITY LEVEL

PX0 IP.0 DEFINES THE EXTERNAL INTERRUPT 0 PRIORITY LEVEL

SCON: SERIAL PORT CONTROL REGISTER, BIT ADDRESSABLE

SCON

SM0 : SCON.7 Serial Port mode specified

SM1 : SCON.6 Serial Port mode specifier

SM2 : SCON.5

REN : SCON.4 Set/cleared by the software to Enable/disable reception

TB8 : SCON.3 the 9th bit that will be transmitted in modes 2 and 3, Set/cleared

By software

RB8 : SCON.2 In modes 2 &3, is the 9th data bit that was received. In mode 1,

If SM2 = 0, RB8 is the stop bit that was received. In mode 0

RB8 is not usedT1 : SCON.1 Transmit interrupt flag. Set by hardware at the end of the 8th bit

Time in mode 0, or at the beginning of the stop bit in the other

Modes. Must be cleared by software

R1 SCON.0 Receive interrupt flag. Set by hardware at the end of the 8th bit

Time in mode 0, or halfway through the stop bit time in the other

Modes. Must be cleared by the software.

TCON TIMER COUNTER CONTROL REGISTER

This is a bit addressable

TF1 TCON.7 Timer 1 overflows flag. Set by hardware when the Timer/Counter 1

Overflows. Cleared by hardware as processor

TR1 TCON.6 Timer 1 run control bit. Set/cleared by software to turn Timer

Counter 1 On/off


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TF0 TCON.5 Timer 0 overflows flag. Set by hardware when the timer/counter 0

Overflows. Cleared by hardware as processor

TR0 TCON.4 Timer 0 run control bit. Set/cleared by software to turn timer

Counter 0 on/off.

IE1 TCON.3 External interrupt 1 edge flag

ITI TCON.2 Interrupt 1 type control bit

IE0 TCON.1 External interrupt 0 edge

IT0 TCON.0 Interrupt 0 type control bit.

TF 1T R1T F0T R0IE IITI I E 0IT 0


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Light dependent resistors or LDRs are often used in circuits where it is necessaryto detect the presence or the level of light. They can be described by a variety of

names from light dependent resistor, LDR, photoresistor, or even photo cell(photocell) or photoconductor.

Although other devices such as photodiodes or photo-transistor can also beused, LDRs are a particularly convenient electronics component to use. Theyprovide large change in resistance for changes in light level.

In view of their low cost, ease of manufacture, and ease of use LDRs have beenused in a variety of different applications. At one time LDRs were used inphotographic light meters, and even now they are still used in a variety ofapplications where it is necessary to detect light levels.

What is an LDR or light dependent resistor

A photoresistor or light dependent resistor is a component that is sensitive tolight. When light falls upon it then the resistance changes. Values of theresistance of the LDR may change over many orders of magnitude the value ofthe resistance falling as the level of light increases.


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It is not uncommon for the values of resistance of an LDR or photoresistor to beseveral megohms in darkness and then to fall to a few hundred ohms in brightlight. With such a wide variation in resistance, LDRs are easy to use and thereare many LDR circuits available.

LDRs are made from semiconductor materials to enable them to have their lightsensitive properties. Many materials can be used, but one popular material forthese photoresistors is cadmium sulphide (CdS).

How an LDR works

It is relatively easy to understand the basics of how an LDR works withoutdelving into complicated explanations. It is first necessary to understand that anelectrical current consists of the movement of electrons within a material. Goodconductors have a large number of free electrons that can drift in a given

direction under the action of a potential difference. Insulators with a highresistance have very few free electrons, and therefore it is hard to make the themmove and hence a current to flow.

An LDR or photoresistor is made any semiconductor material with a highresistance. It has a high resistance because there are very few electrons that arefree and able to move - the vast majority of the electrons are locked into thecrystal lattice and unable to move. Therefore in this state there is a high LDRresistance.

As light falls on the semiconductor, the light photons are absorbed by the

semiconductor lattice and some of their energy is transferred to the electrons.This gives some of them sufficient energy to break free from the crystal lattice sothat they can then conduct electricity. This results in a lowering of the resistanceof the semiconductor and hence the overall LDR resistance.

The process is progressive, and as more light shines on the LDR semiconductor,so more electrons are released to conduct electricity and the resistance fallsfurther.

LDR summary

LDRs are very useful components that can be used for a variety of light sensingapplications. As the LDR resistance varies over such a wide range, they areparticularly useful, and there are many LDR circuits available beyond any shownhere. In order to utilise these components, it is necessary to know something ofhow an LDR works, which has been explained above.


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Types of wind turbines

Wind farm in the Tehachapi Mountains, California.

Wind turbines can be separated into two general types based on the axis

about which the turbine rotates. Turbines that rotate around a horizontal axisare most common. Vertical axis turbines are less frequently used.

Wind turbines can also be classified by the location in which they are to be

used. Onshore, offshore, or even aerial wind turbines have unique design

characteristics which are explained in more detail in the section on Turbine

design and construction.
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Wind turbines may also be used in conjunction with a solar collectorto

extract the energy due to air heated by the Sun and rising through a large

vertical Solar updraft tower.

Horizontal axis

Horizontal Axis Wind Turbines (HAWT) have the main rotor shaft and

generator at the top of a tower, and must be pointed into the wind by some

means. Small turbines are pointed by a simple wind vane, while large

turbines generally use a wind sensor coupled with a servomotor. Most have a

gearbox too, which turns the slow rotation of the blades into a quicker

rotation that is more suitable for generating electricity.

Since a tower produces turbulence behind it, the turbine is usually pointed

upwind of the tower. Turbine blades are made stiff to prevent the blades

from being pushed into the tower by high winds. Additionally, the blades are

placed a considerable distance in front of the tower and are sometimes tilted

up a small amount.

Downwind machines have been built, despite the problem of turbulence,

because they don't need an additional mechanism for keeping them in line

with the wind, and because in high winds, the blades can be allowed to bend

which reduces their swept area and thus their wind resistance. Because

turbulence leads to fatigue failures and reliability is so important, most

HAWTs are upwind machines.

There are several types of HAWT:

WindmillsThese four- (or more) bladed squat structures, usually with wooden

shutters or fabric sails, were pointed into the wind manually or via a

tail-fan. These windmills, generally associated with the Netherlands,were historically used to grind grain or pump water from low-lying

land. They greatly accelerated shipbuilding in the Netherlands, and

were instrumental in keeping itspolders dry.

American-style farm windmills
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These windmills were used by American prairie farmers to generate

electricity and to pump water. They typically had many blades,

operated at tip speed ratios (defined below) not better than one, and

had good starting torque. Some had small direct-current generators

used to charge storage batteries, to provide a few lights, or to operate

a radio receiver. The rural electrification connected many farms to

centrally-generated power and replaced individual windmills as a

primary source of farm power in the 1950s. Such devices are still used

in locations where it is too costly to bring in commercial power.

Wind turbines nearAalborg, Denmark

Common modern wind turbinesUsually three-bladed, sometimes two-bladed or even one-bladed (and

counterbalanced), and pointed into the wind by computer-controlled

motors. The rugged three-bladed turbine type has been championed by

Danish turbine manufacturers. These have high tip speeds of up to 6x

wind speed, high efficiency, and low torque ripple which contributes

to good reliability. This is the type of turbine that is used

commercially to produce electricity. They are usually white in color.

Ducted rotorStill something of a research project, the ducted rotor consists of aturbine inside a duct which flares outwards at the back. They are also

referred as Diffuser-Augmented Wind Turbines (i.e. DAWT). The

main advantage of the ducted rotor is that it can operate in a wide

range of winds and generate a higher power per unit of rotor area.

Another advantage is that the generator operates at a high rotation
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rate, so it doesn't require a bulky gearbox, so the mechanical portion

can be smaller and lighter. A disadvantage is that (apart from the

gearbox) it is more complicated than the unducted rotor and the duct

is usually quite heavy, which puts an added load on the tower.

Co-axial, multi-rotor horizontal axis turbines

Two or more rotors may be mounted to the same driveshaft, with their

combined co-rotation together turning the same generator - fresh wind is

brought to each rotor by sufficient spacing between rotors combined with an

offset angle alpha from the wind direction. Wake vorticity is recovered as

the top of a wake hits the bottom of the next rotor. Power has been

multiplied several times using co-axial, multiple rotors in testing conductedby inventor and researcher Douglas Selsam, for the California Energy

Commission in 2004. The first commercially available co-axial multi-rotor

turbine is the patented dual-rotor American Twin Superturbine from Selsam

Innovations in California, with 2 propellers separated by 12 feet. It is the

most powerful 7-foot diameter turbine available, due to this extra rotor.

Counter-rotating horizontal axis turbines

Counter rotating turbines can be used to increase the rotation speed of the

electrical generator. As of 2005, no large practical counter-rotating HAWTsare commercially sold. When the counter rotating turbines are on the same

side of the tower, the blades in front are angled forwards slightly so as to

avoid hitting the rear ones. If the turbine blades are on opposite sides of the

tower, it is best that the blades at the back be smaller than the blades at the

front and set to stall at a higher wind speed. This allows the generator to

function at a wider wind speed range than a single-turbine generator for a

given tower. To reduce sympathetic vibrations, the two turbines should turn

at speeds with few common multiples, for example 7:3 speed ratio. Overall,

this is a more complicated design than the single-turbine wind generator, butit taps more of the wind's energy at a wider range of wind speeds.

Appa designed and demonstrated a contra rotor wind turbine in FY 2000-

2002 funded by California Energy Commission. This study showed 30 to

40% more power extraction than a comparable single rotor system. Further it
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was observed that the slower the rotor speed better the performance.

Consequently Megawatt machines benefit most.

Cyclic stresses and vibration

Cyclic stresses fatigue the blade, axle andbearing material, and were a

major cause of turbine failure for many years. Because wind velocity

increases at higher altitudes, the backward force and torque on a horizontal

axis wind turbine (HAWT) blade peaks as it turns through the highest point

in its circle. The tower hinders the airflow at the lowest point in the circle,which produces a local dip in force and torque. These effects produce a

cyclic twist on the main bearings of a HAWT. The combined twist is worst

in machines with an even number of blades, where one is straight up when

another is straight down. To improve reliability, teetering hubs have been

used which allow the main shaft to rock through a few degrees, so that the

main bearings do not have to resist the torque peaks.

When the turbine turns to face the wind, the rotating blades act like a

gyroscope. As it pivots, gyroscopic precession tries to twist the turbine into aforward or backward somersault. For each blade on a wind generator's

turbine, precessive force is at a minimum when the blade is horizontal and at

a maximum when the blade is vertical. This cyclic twisting can quickly

fatigue and crack the blade roots, hub and axle of the turbine.

Vertical axis

Vertical Axis Wind Turbines (or VAWTs) have the main rotor shaft running

vertically. The advantages of this arrangement are that the generator and/or

gearbox can be placed at the bottom, near the ground, so the tower doesn'tneed to support it, and that the turbine doesn't need to be pointed into the

wind. Drawbacks are usually the pulsating torque produced during each

revolution, and the difficulty of mounting vertical axis turbines on towers,

meaning they must operate in the slower, more turbulent air flow near the

ground, with lower energy extraction efficiency.
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H-Darrieus-turbine

Darrieus wind turbineThese are the "eggbeater" turbines. They have good efficiency, but

produce large torque ripple and cyclic stress on the tower, which

contributes to poor reliability. Also, they generally require some

external power source, or an additional Savonius rotor, to start

turning, because the starting torque is very low. The torque ripple is

reduced by using 3 or more blades.

Giromill is a type of Darrieus

These lift-type devices have vertical blades. The cycloturbine varietyhas variable pitch, to reduce the torque pulsation and self-start . The

advantages of variable pitch are high starting torque, a wide, relatively

flat torque curve, a lower blade speed ratio, a higher coefficient of

performance, more efficient operation in turbulent winds, and a lower

blade speed ratio which lowers blade bending stresses. Straight, V, or

curved blades may be used.

Savonius wind turbineThese are the familiar two- (or more) scoop drag-type devices used in anemometers

and in the Flettner vents commonly seen on bus and van roofs, and some high-reliability low-efficiency power turbines. They always self-start (if at least three

scoops). They can sometimes have long helical scoops, to give smooth torque. The

Banesh rotor and especially the Rahai rotor improve efficiency by shaping theblades to produce significant lift as well as drag.
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Tower height

The wind blows faster at higher altitudes because of the drag of the surface(sea or land) and the viscosity of the air. The variation in velocity with

altitude, called wind shear, is most dramatic near the surface.

Wind turbines of varied height generating electricity in California.

Typically, in daytime the variation follows the 1/7th power law, which

predicts that wind speed rises proportionally to the seventh root of altitude.

Doubling the altitude of a turbine, then, increases the expected wind speeds

by 10% and the expected power by 34%. Doubling the tower height

generally requires doubling the diameter as well, increasing the amount of

material by a factor of eight.

In night time, or better: when the atmosphere becomes stable, wind speed

close to the ground usually subsides whereas at turbine hub altitude it does

not decrease that much or may even increase. As a result the wind speed is

higher and a turbine will produce more power than expected from the 1/7th

power law: doubling the altitude may increase wind speed by 20% to 60%.

A stable atmosphere is caused by radiative cooling of the surface and is

common in a temperate climate: it usually occurs when there is a (partly)

clear sky at night. When the (high altitude) wind is strong (10 meter wind

speed higher than approximately 6 to 7 m/s) the stable atmosphere isdisrupted because of friction turbulence and the atmosphere will turn

neutral. A daytime atmosphere is either neutral (no net radiation; usually

with strong winds and/or heavy clouding) orunstable (rising air because of

ground heating by the sun). Here again the 1/7th power law applies or is

at least a good approximation of the wind profile.
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For HAWTs, tower heights approximately twice to triple the blade length

have been found to balance material costs of the tower against better

utilisation of the more expensive active components.

Number of blades

For small (novelty or urban) HAWT turbines manufacturers typically shipthree-bladed turbines with three separate blades that must be assembled

onsite, into a central hub. Without careful assembly ensuring accurate

dynamic balance of the blades, the turbine can shake itself apart.

Most wind turbines have three blades. Very small turbines may use two

blades for ease of construction and installation. Vibration intensity decreases

with larger numbers of blades. Noise and wear are generally lower, and

efficiency higher, with three instead of two blades.

Turbines with larger numbers of smaller blades operate at a lowerReynoldsnumberand so are less efficient. Small turbines with 4 or more blades suffer

further losses as each blade operates partly in the wake of the other blades.

Also, the cost of the turbine usually increases with the number of blades.

Rotation controlTip speed ratio

The ratio between the speed of the wind and the speed of the tips of

the blades of a wind turbine. High efficiency 3-blade-turbines have tip

speed ratios of 6-7.

Modern wind turbines are designed to spin at varying speeds (a consequence

of their generator design, see below). Use of aluminum and composites in

their blades has contributed to low rotational inertia, which means that

newer wind turbines can accelerate quickly if the winds pick up, keeping the

tip speed ratio more nearly constant. Operating closer to their optimal tip
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speed ratio during energetic gusts of wind allows wind turbines to improve

energy capture from sudden gusts that are typical in urban settings.

In contrast, older style wind turbines were designed with heavier steel

blades, which have higher inertia, and rotated at speeds governed by the AC

frequency of the power lines. The high inertia buffered the changes in

rotation speed and thus made power output more stable.

The speed and torque at which a wind turbine rotates must be controlled for

several reasons:

To optimize the aerodynamic efficiency of the rotor in light winds.

To keep the generator within its speed and torque limits.

To keep the rotor and hub within their centripetal force limits. The

centripetal force from the spinning rotors increases as the square of

the rotation speed, which makes this structure sensitive to overspeed.

To keep the rotor and tower within their strength limits. Because the

power of the wind increases as the cube of the wind speed, turbines

have to be built to survive much higher wind loads (such as gusts of

wind) than those from which they can practically generate power.

Since the blades generate more downwind force (and thus put far

greater stress on the tower) when they are producing torque, mostwind turbines have ways of reducing torque in high winds.

To enable maintenance; because it is dangerous to have people

working on a wind turbine while it is active, it is sometimes necessary

to bring a turbine to a full stop.

To reduce noise; As a rule of thumb, the noise from a wind turbine

increases with the fifth power of the relative wind speed (as seen from

the moving tip of the blades). In noise-sensitive environments, the tip

speed can be limited to approximately 60 m/s.

Overspeed control is exerted in two main ways: aerodynamic stalling or

furling, and mechanical braking. Furling is the preferred method of slowing

wind turbines.
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Mechanical braking

A mechanical drum brake ordisk brake is used to hold the turbine at rest for

maintenance. Such brakes are usually applied only after blade furling and

electromagnetic braking have reduced the turbine speed, as the mechanical

brakes would wear quickly if used to stop the turbine from full speed. There

can also be a stick brake.

Turbine size

A person standing beside medium size modern turbine blades.

For a given survivable wind speed, the mass of a turbine is approximately

proportional to the cube of its blade-length. Wind power intercepted by the

turbine is proportional to the square of its blade-length. The maximum

blade-length of a turbine is limited by both the strength and stiffness of its

material.

Labor and maintenance costs increase only gradually with increasing turbine

size, so to minimize costs, wind farm turbines are basically limited by the

strength of materials, and siting requirements.

Typical modern wind turbines have diameters of 40 to 90 meters and are

rated between 500 kW and 2 megawatts. Currently (2005) the most powerful

turbine is rated at 6 MW.
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Generating electricity

For large, commercial size horizontal-axis wind turbines, the generatorismounted in a nacelle at the top of a tower, behind the hub of the turbine

rotor. A speed increasing gearbox may be inserted between the rotor hub and

the generator, so that the generator cost and weight can be reduced.

Commercial size generators have a rotor carrying a field winding so that a

rotating magnetic field is produced inside a set of windings called the stator.

While the rotating field winding consumes a fraction of a percent of the

generator output, adjustment of the field current allows good control over

the generator output voltage. Very small wind generators (a few watts to

perhaps a kilowatt in output) may usepermanent magnets but these are too

costly to use in large machines and do not allow convenient regulation of the

generator voltage.

Electrical generators inherently produce AC power. Older style wind

generators rotate at a constant speed, to matchpower line frequency, which

allowed the use of less costly induction generators. Newer wind turbines

often turn at whatever speed generates electricity most efficiently. The

variable frequency current is then converted to DC and then back to AC,

matching the line frequency and voltage. Although the two conversionsrequire costly equipment and cause power loss, the turbine can capture a

significantly larger fraction of the wind energy. In some cases, especially

when turbines are sited offshore, the DC energy will be transmitted from the

turbine to a central (onshore) inverterfor connection to the grid.

Materials

One of the strongest construction materials available (in 2006) is graphite-

fibre in epoxy, but it is very expensive and only used by some manufacturesfor special load-bearing parts of the rotor blades. Modern rotor blades (up to

126 m diameter) are made of lightweight pultruded glass-reinforced plastic

(GRP), smaller ones also from aluminium. GRP is the most common

material for modern wind turbines.
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Wood and canvas sails were originally used on early windmills.

Unfortunately they require much maintenance over their service life. Also,

they have a relatively high drag (low aerodynamic efficiency) for the force

they capture. For these reasons they were superseded with solid airfoils.

History

High-efficiency wind turbines (foreground) win out over traditional

windmills (background) in most new installations.

Wind machines were used for grinding grain in Persia as early as 200 B.C.

This type of machine was introduced into the Roman Empire by 250 A.D.

By the 14th century Dutch windmills were in use to drain areas of the Rhine

Riverdelta. In Denmarkby 1900 there were about 2500 windmills for

mechanical loads such as pumps and mills, producing an estimated

combined peak power of about 30 MW. The first windmill for electricity

production was built in Denmark in 1890, and in 1908 there were 72 wind-

driven electric generators from 5 kW to 25 kW. The largest machines were

on 24 m towers with four-bladed 23 m diameter rotors.

By the 1930s windmills were mainly used to generate electricity on farms,

mostly in the United States where distribution systems had not yet been

installed. In this period, high tensile steel was cheap, and windmills wereplaced atop prefabricated open steel lattice towers. A forerunner of modern

horizontal-axis wind generators was in service at Yalta, USSRin 1931. This

was a 100 kW generator on a 30 m tower, connected to the local 6.3 kV

distribution system. It was reported to have an annual load factorof 32 per

cent, not much different from current wind machines.
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In 1941 the world's first megawatt-size wind turbine was connected to the

local electrical distribution system on Grandpa's Knob in Castleton,

Vermont, USA. This 1.25 MW Smith-Putnam turbine operated for 1100

hours before a blade failed at a known weak point, which had not been

reinforced due to war-time material shortages. In the 1940s, the U.S. had a

rural electrification project that killed the natural market for wind-generated

power, since network power distribution provided a farm with more

dependable usable energy for a given amount of capital investment.

In the 1970s many people began to desire a self-sufficient life-style. Solar

cells were too expensive for small-scale electrical generation, so some

turned to windmills. At first they built ad-hoc designs using wood and

automobile parts. Most people discovered that a reliable wind generator is a

moderately complex engineering project, well beyond the ability of most

romantics. Some began to search for and rebuild farm wind-generators fromthe 1930s, of which Jacobs wind generators were especially sought after.

Later, in the 1980s, California provided tax rebates for ecologically harmless

power. These rebates funded the first major use of wind power for utility

electricity. These machines, gathered in large wind parks such as at

Altamont Pass would be considered small and un-economic by modern wind

power development standards.

In the 1990s, as aesthetics and durability became more important, turbines

were placed atop steel or reinforced concrete towers. Small generators areconnected to the tower on the ground, then the tower is raised into position.

Larger generators are hoisted into position atop the tower and there is a

ladder or staircase inside the tower to allow technicians to reach and

maintain the generator.

Originally wind generators were built right next to where their power was

needed. With the availability of long distance electric power transmission,

wind generators are now often on wind farms in windy locations and huge

ones are being built offshore, sometimes transmitting power back to land

using high voltagesubmarine cable. Since wind turbines are a renewable

means of generating electricity, they are being widely deployed, but their

cost is often subsidised by taxpayers, either directly or through renewable

energy credits. Much depends on the cost of alternative sources of

electricity. Wind generator cost per unit power has been decreasing by about

four percent per year.
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Companies in wind turbine industry

World market for wind energy plants in 2003

ABB Ltd. Wind turbine generators[3]

Airtricity only operates turbines AWS Truewind, LLC[4] - Wind Energy Consultants

Bergey Windpower[5] Det Norske Veritas - Certification of wind turbines and wind turbine projects

DeWind

Ecotcnia sccl - Spanish manufacturer

Eclectic Energy Ltd - UK manufacturer of small wind turbines, including the grid-linked turbine StealthGen

Eirbyte[7] Supplier of small turbines in Ireland

EMD A/S - WindPRO software package for project design and planning of turbines

Emergya Wind Technologies[8]

Enercon GmbH, Germany - wind turbines up to 6 MW

Gamesa Corporacion Tecnologica

Garrad Hassan and Partners Ltd.

General Electric, through its subsidiaryGE Energy

Hansen Transmissions Int. supplier of multi-MW wind turbine gear units[9]

O'Connor Hush Energy[10] - Australian supplier of small, quiet turbines

LM Glasfiber A/S - Rotor blades ranging from 13.4 to 61.5 m

Moventas Oy - Moventas provides leading mechanical power transmission

technology to the energy and process industries[11]

Natural Power- International wind energy consultancy services

NEG Micon - Merged with Vestas in 2004

Nordex

Pauwels Trafo Belgium/Ireland- Major Wind Turbine Generator TransformerManufacturers

PB Power- Global Engineering Company servicing Power industry

REpower, Germany - wind turbines up to 5 MW

Selsam Innovations / Superturbine Inc. , California multi-rotor wind turbines

http://www.selsam.com

Siemens Wind Power A/S (formerly Bonus Energy A/S)
http://en.wikipedia.org/wiki/ABB_Ltd.http://en.wikipedia.org/wiki/ABB_Ltd.http://www.abb.com/product/us/9AAC100348.aspx?country=EEhttp://www.abb.com/product/us/9AAC100348.aspx?country=EEhttp://en.wikipedia.org/wiki/Airtricityhttp://en.wikipedia.org/w/index.php?title=AWS_Truewind%2C_LLC&action=edithttp://www.awstruewind.com/http://www.awstruewind.com/http://en.wikipedia.org/w/index.php?title=Bergey_Windpower&action=edithttp://www.bergey.com/http://www.bergey.com/http://en.wikipedia.org/wiki/Det_Norske_Veritashttp://en.wikipedia.org/w/index.php?title=DeWind&action=edithttp://en.wikipedia.org/w/index.php?title=Ecot%C3%A8cnia_sccl&action=edithttp://en.wikipedia.org/w/index.php?title=Eclectic_Energy_Ltd&action=edithttp://en.wikipedia.org/w/index.php?title=Eirbyte&action=edithttp://www.eirbyte.com/http://www.eirbyte.com/http://en.wikipedia.org/w/index.php?title=EMD_A/S&action=edithttp://en.wikipedia.org/w/index.php?title=Emergya_Wind_Technologies&action=edithttp://www.directwind.nl/http://www.directwind.nl/http://en.wikipedia.org/wiki/Enercon_GmbHhttp://en.wikipedia.org/w/index.php?title=Gamesa_Corporacion_Tecnologica&action=edithttp://en.wikipedia.org/wiki/Garrad_Hassan_and_Partners_Ltd.http://en.wikipedia.org/wiki/Garrad_Hassan_and_Partners_Ltd.http://en.wikipedia.org/wiki/General_Electrichttp://en.wikipedia.org/wiki/GE_Energyhttp://en.wikipedia.org/wiki/GE_Energyhttp://en.wikipedia.org/w/index.php?title=Hansen_Transmissions_Int.&action=edithttp://en.wikipedia.org/w/index.php?title=Hansen_Transmissions_Int.&action=edithttp://www.hansentransmissions.com/http://www.hansentransmissions.com/http://www.hansentransmissions.com/http://en.wikipedia.org/w/index.php?title=O%27Connor_Hush_Energy&action=edithttp://www.hushenergy.com.au/http://www.hushenergy.com.au/http://en.wikipedia.org/w/index.php?title=LM_Glasfiber_A/S&action=edithttp://en.wikipedia.org/w/index.php?title=Moventas_Oy&action=edithttp://www.moventas.com/http://www.moventas.com/http://en.wikipedia.org/w/index.php?title=Natural_Power&action=edithttp://en.wikipedia.org/w/index.php?title=NEG_Micon&action=edithttp://en.wikipedia.org/w/index.php?title=Nordex&action=edithttp://en.wikipedia.org/w/index.php?title=Pauwels_Trafo_Belgium/Ireland&action=edithttp://en.wikipedia.org/w/index.php?title=PB_Power&action=edithttp://en.wikipedia.org/w/index.php?title=REpower&action=edithttp://en.wikipedia.org/w/index.php?title=Selsam_Innovations_/_Superturbine_Inc.&action=edithttp://en.wikipedia.org/w/index.php?title=Selsam_Innovations_/_Superturbine_Inc.&action=edithttp://www.selsam.com/http://en.wikipedia.org/w/index.php?title=Siemens_Wind_Power_A/S&action=edithttp://en.wikipedia.org/wiki/Image:Windenergy-marked.jpghttp://en.wikipedia.org/wiki/ABB_Ltd.http://www.abb.com/product/us/9AAC100348.aspx?country=EEhttp://en.wikipedia.org/wiki/Airtricityhttp://en.wikipedia.org/w/index.php?title=AWS_Truewind%2C_LLC&action=edithttp://www.awstruewind.com/http://en.wikipedia.org/w/index.php?title=Bergey_Windpower&action=edithttp://www.bergey.com/http://en.wikipedia.org/wiki/Det_Norske_Veritashttp://en.wikipedia.org/w/index.php?title=DeWind&action=edithttp://en.wikipedia.org/w/index.php?title=Ecot%C3%A8cnia_sccl&action=edithttp://en.wikipedia.org/w/index.php?title=Eclectic_Energy_Ltd&action=edithttp://en.wikipedia.org/w/index.php?title=Eirbyte&action=edithttp://www.eirbyte.com/http://en.wikipedia.org/w/index.php?title=EMD_A/S&action=edithttp://en.wikipedia.org/w/index.php?title=Emergya_Wind_Technologies&action=edithttp://www.directwind.nl/http://en.wikipedia.org/wiki/Enercon_GmbHhttp://en.wikipedia.org/w/index.php?title=Gamesa_Corporacion_Tecnologica&action=edithttp://en.wikipedia.org/wiki/Garrad_Hassan_and_Partners_Ltd.http://en.wikipedia.org/wiki/General_Electrichttp://en.wikipedia.org/wiki/GE_Energyhttp://en.wikipedia.org/w/index.php?title=Hansen_Transmissions_Int.&action=edithttp://www.hansentransmissions.com/http://en.wikipedia.org/w/index.php?title=O%27Connor_Hush_Energy&action=edithttp://www.hushenergy.com.au/http://en.wikipedia.org/w/index.php?title=LM_Glasfiber_A/S&action=edithttp://en.wikipedia.org/w/index.php?title=Moventas_Oy&action=edithttp://www.moventas.com/http://en.wikipedia.org/w/index.php?title=Natural_Power&action=edithttp://en.wikipedia.org/w/index.php?title=NEG_Micon&action=edithttp://en.wikipedia.org/w/index.php?title=Nordex&action=edithttp://en.wikipedia.org/w/index.php?title=Pauwels_Trafo_Belgium/Ireland&action=edithttp://en.wikipedia.org/w/index.php?title=PB_Power&action=edithttp://en.wikipedia.org/w/index.php?title=REpower&action=edithttp://en.wikipedia.org/w/index.php?title=Selsam_Innovations_/_Superturbine_Inc.&action=edithttp://www.selsam.com/http://en.wikipedia.org/w/index.php?title=Siemens_Wind_Power_A/S&action=edithttp://en.wikipedia.org/w/index.php?title=Southwest_Windpower&action=edit

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