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Advanced Adjusment of SX440 AVR Controls

2012-02-15T15:30:00.000-08:00

STABILITY ADJUSTMENT

The AVR includes a stability or damping circuit to provide good steady state and transient performance of the
generator.

The correct setting can be found by running the generator at no load and slowly turning the stability control anti-clockwise until the generator voltage starts to become unstable.

The optimum or critically damped position is slightly clockwise from this point (i.e. where the machine volts are stable but close to the unstable region).
OPTIMUM RESPONSE SELECTION

The stability selection ‘jumper’ should be correctly linked, A-B, B-C or A-C at the bottom of the board for the frame size of the generator, (see drawing).

UNDER FREQUENCY ROLL OFF (UFRO)
ADJUSTMENT

The AVR incorporates an underspeed protection circuit which gives a volts/Hz characteristic when the generator speed falls below a presettable threshold known as the "knee" point.

The red Light Emitting Diode (LED) gives indication that the UFRO circuit is operating.

The UFRO adjustment is preset and sealed and only requires the selection of 50 / 60Hz using the jumper link.

For optimum setting, the LED should illuminate as the frequency falls just below nominal, i.e. 47Hz on a 50Hz
system or 57Hz on a 60Hz system.

DROOP ADJUSTMENT

Generators intended for parallel operation are fitted with a quadrature droop C.T. which provides a power factor dependent signal for the AVR. The C.T. is connected to S1, S2 on the AVR.

The DROOP adjustment is normally preset in the works to give 5% voltage droop at full load zero power factor.

Clockwise increases the amount of C.T. signal injected into the AVR and increases the droop with lagging power factor (cos Ø). With the control fully anti-clockwise there is no droop.
TRIM ADJUSTMENT

An analogue input (A1 A2) is provided to connect to the Newage Power Factor Controller or other devices. It is designed to accept dc signals up to +/- 5 volts.

CAUTION Any devices connected to this input must be fully floating and galvanically isolated from ground, with an insulation capability of 500 Vac. Failure to observe this could result in equipment damage.

The dc signal applied to this input adds to the AVR sensing circuit. A1 is connected to the AVR 0 volts. Positive on A2 increases excitation. Negative on A2 decreases excitation.

The TRIM control allows the user to adjust the sensitivity of the input. With TRIM fully anti-clockwise the externally applied signal has no effect. Clockwise it has maximum effect.

Normal setting is fully clockwise when used with a Newage Power Factor Controller.

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Voltage Adjusment of SX440 AVR Controls

2012-02-14T15:23:00.000-08:00

VOLTAGE ADJUSTMENT

The generator output voltage is set at the factory, but can be altered by careful adjustment of the VOLTS control on the AVR board, or by the external hand trimmer if fitted. Terminals 1 and 2 on the AVR will be fitted with a shorting link if no hand trimmer is required.

CAUTION Do not increase the voltage above the rated generator voltage. If in doubt, refer to the rating plate mounted on the generator case.
CAUTION Do not ground any of the hand trimmer terminals as these could be above earth potential. Failure to observe this could cause equipment damage.

If a replacement AVR has been fitted or re-setting of the VOLTS adjustment is required, proceed as follows:

CAUTION
1. Before running generator, turn the VOLTS control fully anti-clockwise.
2. Turn remote volts trimmer (if fitted) to midway position.
3. Turn STABILITY control to midway position.
4. Connect a suitable voltmeter (0-300V ac) across line to neutral of the generator.
5. Start generator set, and run on no load at nominal frequency e.g. 50-53Hz or 60-63Hz.
6. If the red Light Emitting Diode (LED) is illuminated, refer to the Under Frequency Roll Off (UFRO) adjustment.
7. Carefully turn VOLTS control clockwise until rated voltage is reached.
8. If instability is present at rated voltage, refer to stability adjustment, then re-adjust voltage if necessary.
9. Voltage adjustment is now completed.

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Design Detail SX440 AVR

2012-02-14T15:00:00.000-08:00

The main functions of the AVR are:

Potential Divider and Rectifier takes a proportion of the generator output voltage and attenuates it. The potential divider is adjustable by the AVR Volts potentiometer and external hand trimmer (when fitted). The output from the droop CT is also added to this signal. An isolating transformer is included allowing connection to various winding configurations. A rectifier converts the a.c. input signal into d.c. for further processing.

The Sensing Loss Detector is an electronic changeover switch, which normally connects the Amplifier (Amp) to the Voltage Sensing input and automatically changes over to the Power input when the normal sensing voltage is lost.

The DC Mixer adds the Analogue input signal the Sensing signal.

The Amplifier (Amp) compares the sensing voltage to the Reference Voltage and amplifies the difference (error) to provide a controlling signal for the power devices. The Ramp Generator and Level Detector and Driver infinitely control the conduction period of the Power Control Devices and hence provides the excitation system with the required power to maintain the generator voltage within specified limits.

The Stability Circuit provides adjustable negative ac feedback to ensure good steady state and transient performance of the control system.

The Low Hz Detector measures the period of each electrical cycle and causes the reference voltage to be reduced approximately linearly with speed below a presettable threshold. A Light Emitting Diode gives indication of underspeed running.

The Synchronising circuit is used to keep the Ramp Generator and Low Hz Detector locked to the generator waveform period.

The Low Pass Filter prevents distorted waveforms affecting the operation of the AVR control circiut

Power Control Devices vary the amount of exciter field current in response to the error signal produced by the Amplifier.

Suppression components are included to prevent sub cycle voltage spikes damaging the AVR components and also to reduce the amount of conducted noise on the generator terminals..

The Power Supply provides the required voltages for the AVR circuitry.

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Technical Specification SX440 AVR

2012-02-13T14:31:00.000-08:00

INPUT

Voltage 190-264V ac
Frequency 50-60 Hz nominal
Phase 1
Wire 2

OUTPUT

Voltage max 90V dc at 207V ac input
Current continuous 4A dc intermittent 6A for 10 secs
Resistance 15 ohms minimum

REGULATION

+/- 1% (see note 1)

THERMAL DRIFT

0.04% per deg. C change in AVR ambient (note 2)

TYPICAL SYSTEM RESPONSE

AVR response 20ms
Filed current to 90% 80 ms
Machine Volts to 97% 300ms

EXTERNAL VOLTAGE ADJUSTMENT

+/-10% with 1 k ohm 1 watt trimmer (see note 3)

UNDER FREQUENCY PROTECTION

Set point 95% Hz (see note 4)
Slope 170% down to 30 Hz

UNIT POWER DISSIPATION

12 watts maximum

BUILD UP VOLTAGE

4 Volts @ AVR terminals

ANALOGUE INPUT

Maximum input +/- 5V dc (see note 5)
Sensitivity 1v for 5% Generator Volts (adjustable)
Input resistance 1k ohm

QUADRATURE DROOP INPUT

10 ohms burden
Max. sensitivity 0.07 A for 5% droop 0PF
Max. input: 0.33A

ENVIRONMENTAL

Vibration 20-100 Hz 50mm/sec

100Hz – 2kHz 3.3g

Operating temperature -40 to +70 oC
Relative Humidity 0-70 oC 95% (see note 6)
Storage temperature -55 to +80 oC

NOTES

With 4% engine governing.
After 10 minutes.
Applies to Mod status S onwards. Generator de-rate may apply. Check with factory.
Factory set, semi-sealed, jumper selectable.
Any device connected to the analogue input must be fully floating (galvanically isolated from ground), with an insulation strength of 500V ac.
Non condensing.

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SX440 - Automatic Voltage Regulator (AVR)

2012-02-13T10:41:00.000-08:00

SX440 is a half-wave phase-controlled thyristor type Automatic Voltage Regulator (AVR) and forms part of the excitation system for a brush-less generator. In addition to regulating the generator voltage, the AVR circuitry includes under-speed and sensing loss protection features. Excitation power is derived directly from the generator terminals.

Positive voltage build up from residual levels is ensured by the use of efficient semiconductors in the power circuitry of the AVR. The AVR is linked with the main stator windings and the exciter field windings to provide closed loop control of the output voltage with load regulation of +/- 1.0%.

In addition to being powered from the main stator, the AVR also derives a sample voltage from the output windings for voltage control purposes. In response to this sample voltage, the AVR controls the power fed to the exciter field, and hence the main field, to maintain the machine output voltage within the specified limits, compensating for load, speed, temperature and power factor of the generator.

A frequency measuring circuit continually monitors the generator output and provides output under-speed protection of the excitation system, by reducing the output voltage proportionally with speed below a pre-settable threshold. A manual adjustment is provided for factory setting of the under frequency roll off point, (UFRO).

This can easily be changed to 50 or 60 Hz in the field by push-on link selection.

Provision is made for the connection of a remote voltage trimmer, allowing the user fine control of the generator's output. An analogue input is provided allowing connection to a Newage Power Factor controller or other external devices with compatible output.

The AVR has the facility for droop CT connection, to allow parallel running with other similarly equipped generators.

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Concentrated Solar Panel a New Efficiency Record

2012-02-12T19:48:00.000-08:00

Semprius, a startup that makes miniscule solar cells capable of capturing concentrated sunlight without costly cooling systems, announced this week that it had made the world's most efficient solar panel.
The company's solar panels use tiny solar cells made of gallium arsenide—the record-breaking solar module contains hundreds of such solar cells, each about the width of a line drawn by a ball-point pen, arranged under lenses that concentrate sunlight 1,100 times.
Gallium arsenide is far better at absorbing sunlight than silicon, the material used in most solar cells, but it's also more expensive. Furthermore, although concentrated solar modules use less semiconducting material, they usually require expensive optics, cooling systems, and tracking systems to keep them aimed at the sun.
Semprius's microscaled solar cells are inherently much better at dissipating heat, making them cheaper.
Semprius's modules have another advantage: whereas a silicon solar cell only efficiently absorbs a narrow band of sunlight, the solar cells in this module are made of three layers of gallium arsenide, each modified to convert a different part of the solar spectrum into electricity.
Tests by a third-party certified the efficiency of Semprius's solar panel at 33.9 percent, marking the first time any solar module has been able to convert more than one-third of the sunlight that falls on it into electricity. Conventional silicon solar panels typically convert less than 15 percent of light into electricity, and the record for a silicon solar panel is 22.9 percent. The previous record for any solar panel was 32 percent, Semprius says.
One-off, experimental modules have achieved higher efficiencies, but Semprius's record-setting module is designed for commercial use. It was made with the same type of equipment that the company is installing in a small factory in Henderson, North Carolina, that it will open this summer. "It's a good indication of the efficiencies our customers can expect," says Joe Carr, Semprius's CEO.
Semprius's process forms tens of thousands of tiny solar cells on a single wafer of gallium arsenide, and uses chemical etching and a robotic system to transfer each layer to an inexpensive substrate. The same gallium-arsenide wafer can be reused many times, reducing costs. The approach is based on a method for transferring small electronics from a wafer to other substrates that was developed by John Rogers, a professor of materials science and engineering at the University of Illinois at Urbana-Champaign.

Deif Generator PPU (Paralleling and Protection Unit)

2012-02-03T09:44:00.000-08:00

The PPU generator controller is a microprocessor-based control unit containing all necessary functions for control of a synchronous generator. The PPU can synchronise the generator and after synchronisation carry out all necessary generator control and protective functions.

The PPU contains all necessary 3-phase measuring circuits and presents all values and alarms on the LCD display. Programming is easily done via a menu structure in the display (password protected) or via the RS232 PC connection and the multi-line 2 Windows® based service software. The service software offers additional features such as monitoring of all relevant information during commissioning, saving/download of settings and download of software updates.

The PPU is a compact all-in-one unit designed for generators running:

stand-alone
parallel with other generators
parallel with the mains

The PPU is well-suited for PLC-controlled systems, interfacing can be done via binary and analogue I/O’s or
via (optional) serial communication. The PPU carries out a cyclical self-test, displaying error messages in clear text and indicating errors with relay outputs, should any errors occur.

Download Autocad drawings

Download Documentation

CSQ 3 - Check Synchronising Relay

2012-01-15T10:07:00.000-08:00

The CSQ-3 is a microprocessor-based synchronising unit. It can be used in any kind of installation where manual or semi-automatic synchronising is required. The CSQ-3 is available in two different versions optimised for land or marine applications respectively.

Download Documentation

Floating Wind Farms

2012-01-08T23:19:00.000-08:00

Even some energy-conscious Massachusetts residents oppose a plan to put dozens of electricity generating wind turbines on towers about eight kilometers off the southern coast of Cape Cod, saying they would be an eyesore. But huge turbines in development at General Electric could make battles with coastal residents a thing of the past. Researchers say the turbines could be placed on ﬂ oating platforms, far at sea and invisible from the shore.
In March, GE announced a $27 million partnership with the U.S. Department of Energy to develop 5- to 7 megawatt turbines by 2009, supplanting the company’s current 3.6-megawatt turbines. Each of these giant energy factories, with rotors 140 meters in diameter, would produce enough electricity to power up to 1,750 homes and at a more economical rate than smaller turbines, since the cost of building offshore wind farms depends more on the number of turbines than on their size.
Meanwhile, a group of MIT researchers led by Paul Sclavounos, a professor of mechanical engineering and naval architecture, have demonstrated the feasibility of placing such turbines atop large ﬂ oating cylinders ballasted with concrete and anchored to the seaﬂ oor by cables. With this design, wind farms could be located in water ranging from 30 meters deep to 300 far out on the continental shelf, where they not only would be invisible from shore but also would catch more wind.

RSQ 3 - Read Synchroscope

2011-12-23T10:21:00.000-08:00

The RSQ-3 is a microprocessor-based synchronising unit, providing visual indication of relevant values for synchronising a generator to a net (busbar).
It can be used in any kind of installation requiring manual synchronising.

Download Documentation

Multilingual Mobile Messenger

2011-12-21T18:19:00.000-08:00

“Giant waves coming, rush 1,000 meters away from the beach.” These 10 words, if sent to mobile phones in the Bahasa, Malay, Sinhala, Tamil, and Telugu languages, might have saved thousands of people from the Indian Ocean tsunami of 2004. But even if South Asia had had a tsunami detection system in place which it didn’t authorities would have had little chance of distributing such a message, given the variety of languages and writing systems used in the region.
Now, Geneva Software Technologies in Bangalore, India, has developed software that will translate English text messages into multiple languages and send a translation to any cellular phone or mobile device in the world, no matter what character set it’s programmed to use. India’s Ministry of Science and Technology announced in February that it intends to use Geneva’s system to deliver disaster alerts.
Existing text-messaging technology requires that both sender and receiver have devices that use Unicode, the standard international system for representing characters on a digital screen. But in rural areas of developing countries, few people can afford Unicode-compliant handsets.
The system Geneva devised can display characters from 14 Indian languages and 57 others used around the world without the need for common standards. Instead, language characters are transmitted as pictures encoded in simple binary format, which almost any phone can render on-screen. Messages can be targeted to speciﬁc regions using the cellular networks’ databases of phone subscribers’ preferred languages.
“With our technology, a message in any language can be sent to any mobile as long as it supports picture messaging,” says Vinjamuri Ravindra, an electrical engineer and R&D director with Geneva.
The multilingual messaging software is compatible with most types of cell phones used in Asia and is compact enough to be stored on a subscriber identity module (SIM) card. “This is an example of how information technology could make a big difference in disaster warning,” says former Indian science and technology secretary Valangiman Ramamurthy, whose department contributed $880,000 to the product’s development.
Like all computer-rendered translations, Geneva’s vary in accuracy, depending in part on their sources’ subjects and contexts. But the company has been working with the Indian Meteorological Department to create standard templates that should minimize this problem in disaster alerts.

Gravity Tractor - How to lasso wayward asteroids

2011-11-04T18:46:00.000-07:00

Sooner or later, say astronomers, an asteroid will be discovered on a collision course with Earth. Humanity will then begin all-out planning to prevent an impact. But while there are already plenty of ideas about how to shove asteroids out of Earth’s way, nobody knows whether any of them would work.

To change that, two groups in the United States and Europe have been developing separate plans for robotic missions to visit nonthreatening asteroids, try to deflect their orbits, and watch how they respond. One group is the private B612 Foundation of Tiburon, CA, which aims to launch an unmanned spacecraft sometime in the next decade to try out a new idea for diverting an asteroid without even touching it. If a spacecraft flew to an asteroid decades before its expected impact and hovered there for years the required period would vary according to the masses of the spacecraft and the asteroid the slight gravitational pull of the spacecraft itself might change the asteroid’s orbit enough to turn a hit into a miss, according to a study published last November in the journal Nature by NASA astronauts Stanley Love and Edward Lu, who is a member of the

board of B612. They call the concept the “gravity tractor.”

The tractor could deflect an asteroid before it passes through a “keyhole,” an imaginary hoop in space through which asteroids must pass if they are to strike Earth; bypassing such a keyhole would ensure a miss. Influencing an asteroid without touching it could be an advantage, since some asteroids are thought to be loosely bound piles of rubble that could simply fall apart under the inlfuence of a more direct push, such as a nuclear detonation. At the same time, the European Space Agency has been planning a mission called Don Quijote, which would send two robot craft to intercept an asteroid. One would crash into it, perhaps nudging it aside, while the other would fly nearby to observe the results.

The B612 researchers and the European agency began “exploratory discussions” about combining the two concepts into one cheaper mission, testing first the no touch method and then the impact, says Rusty Schweickart, a former Apollo astronaut and one of the founders of B612.