EEWeb Pulse - Issue 72 by EEWeb

INTERVIEW

EEWeb Issue 72

November 13, 2012

Bob Heile

Chairman & CEO ZigBee TECHNICAL ARTICLE

Fiber Optics for Wind Turbines TECHNICAL ARTICLE

Auto-calibration Capacitive Sensors

Electrical Engineering Community

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TABLE OF CONTENTS

Bob Heile ZIGBEE ALLIANCE Interview with Bob Heile - Chairman and CEO

Featured Products

Capacitive Sensors with Auto-Callibration For Human Touch Interfaces

BY EMMANUEL T. NANA WITH NXP SEMICONDUCTORS How NXP is taking a new approach to capacitive sensors that lets the sensor adjust itself continuously to its environment.

Fiber Optic Products for Wind Turbine Applications

BY ALEK INDRA WITH AVAGO TECHNOLOGIES With the issue of global warming taking center stage, Avago offers highly reliable industrial fiber optic components for wind turbine and wind farm appliactions.

RTZ - Return to Zero Comic

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Heil ZigBee 4

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INTERVIEW

ZigBee Alliance offers green and global wireless standards that contribute to the ever-expanding internet of things. We spoke with the CEO and Chairman, Bob Heile, about implementing a standard, the growing global ecosystem using the standards and the future of the wireless sensor industry.

ile e

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EEWeb PULSE How did you get into engineering? I have been active in the data communications field since when modems were considered state-ofthe-art. I ran the modem business for Motorola Codex throughout the 1980s and grew that business up from what was basically a hardware thing up into the modern age of signal processing and all of the things we take for granted in our PCs today. I got into wireless at the same time because wireless local area networking was a very interesting new area. It wasn’t until the late 80s, when there were unlicensed ISM (Industrial, Scientific, Medical) bands, that they were even practical to consider. I launched that with a group and we started the company Wireless Area Local Networking. The initial findings wound up being one of the founding members of 802.11 in 1990. At the end of the decade, I started doing the

got started with 802.15.4, which is the radio technology that was really adapted for sensor networks. I formed a joint venture with an industry group developing market requirements for sensor networks that was out there, looking at similar process from the marketing side. That joint venture is what morphed into the ZigBee alliance in 2002. Tell us about the ZigBee Alliance. What are some of the goals and objectives you have? The Alliance was formed ten years ago with a very simple mission. We had a core group of companies that were very interested and surveyed the landscape and what existed in terms of wireless standards. Those standards were ones that were near and dear to my heart because I was involved with their creation, mainly 802.11 and Bluetooth, but neither of those technologies were suitable for

global standards for wireless sensor networks. It was viewed then, and emerging to be the truth now, that it was going to be a very important paradigm moving forward. That was what we set out to do initially, but there was one more piece to that, which is a little different than the usual standards development organization. Usually you write the standard and you’re done with it, but we felt that it was very necessary to have a good, unbiased, 3rd party mechanism to do certification and authentication so that manufacturers could verify that their products could interoperate. The whole point of a standard, especially in the case of wireless sensor networks, is achieving interoperability. We actually set up a certification program, validated at groups at certified test houses, either independent organization, so the company anonymity is preserved when you’re out there

“Like I said, [the standard] has successfully solved a lot of the unique problems of sensor networking, which is the ability to scale to large sizes, the ability to be self-organized and solving security issues and battery power efficiency.” same thing again, but low-power radio technology because of the impending opportunity, which is how 802.15 got launched. Back then, Bluetooth was just getting started, so I started a joint venture with Bluetooth and 802.15.1 was the IEEE standard version of BT. The more important stuff was when we

what today we’d call the “internet of things,” which could be networks of thousands of devices. 802.11 is a great WLAN. Bluetooth is a great peer-to-peer wireless headset, but that’s not what the mainstream problem is for sensor networks. The mission was to establish an organization that could create

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certifying products. That’s been very successful. Today, we’re over 425 companies worldwide. Over half of the organization’s members are outside North America, so when I say it’s a global organization, I mean it. With all of the efforts and activities, we’re starting to see some real market take-up. We

INTERVIEW are declared as having cross the chasm in 2010 and we’ve have seen certified products growing since that time at a rate of 4.3% over the last 11 months, so it’s now over 540 certified products. We have the go-to standard for smart-metering and home area networking. Like I said, it has successfully solved a lot of the unique problems of sensor networking, which is the ability to scale to large sizes, the ability to be self-organized and solving security issues and battery power efficiency. We are a Standard Development Organization (SDO). We’re organized as a 501c6, just like IEEE.

We legally exist to help companies get together and develop open, public standards. We have no other mission and no other product aside from global standards. What is your position at the ZigBee Alliance? My position is Chairman of the ZigBee Alliance and Chief Executive Officer. Basically, my mission is to make sure things are going smoothly and people are tending to what they

need to attend to. The alliance is there to create standards and my role is to create an organization that allows companies to do that in an effective way and to manage those standards and to evolve them and improve them over time. I also try to educate the community and marketplace whenever I can about what they need and what’s happening. If you have a good set of standards and people like them, then the rest follows—I get more and more involved. We aren’t necessarily going after members, we are going after the mission of creating global standards for wireless sensor

networks and we’ve been very successful at that and we have a very large community of interest out there as a result—420 member companies are now participating in the standards process. It’s a very lively global ecosystem. In what ways do work with companies in the Alliance? A function the Alliance performs on behalf of its members is talking about the capabilities and the

“Over half of the organization’s members are outside North America, so when I say it’s a global organization, I mean it.”

mission with other companies. We also engage in trade shows and technology events and set things up where we sometimes have a booth or a speaking position. These events really become an opportunity for the companies to gain visibility. We talk to users as well, because they understand what is there and what is capable so that they can go back and ask their suppliers for the appropriate product because it will solve the specific problem that they face. It’s not sales, but things Visit www.eeweb.com

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that drive understanding of the products. We bring various OEMs together to share their development experiences with people who are just starting out. It allows people to get a good understanding and also gets people acquainted with design tricks and stuff to help people along. The attitude in the market is, in part, understanding what other people have done and what decisions have been made so that they can make intelligent decisions. What do you see as the biggest challenges for large, mass adoption? It varies. Even though a wireless sensor network is very generic in architecture and character, we’re not out there building a grand internet of things from the bottom up. We think about home automation and about commercial building automation. What this

means is that we not only design a standard networking capability, but an application that allows for interoperability. We’re seeing, for instance, home automation and smart energy have been growing the fastest because, in the case of energy management, we know we have shortages of electricity, we know we need to do residential demand response. Building the smart-grid is strategically important to a lot of nations. The challenges for smart energy is making people comfortable in the early market phase, that this technology is not just a flash in the pan, but it will be around for years to come, because that’s the lifetime of these designs. Do you have tools that help hardware developers integrating into the standards? Absolutely. We have seven of the world’s top ten companies

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in the Alliance and we have a number of fabless semiconductor companies—so it’s a very rich ecosystem. On the ZigBee website, there’s a “Products” page and all of the silicon providers all have training and development kits to help with designs and to see the network performance. There’s a lot of good stuff you can pick from and a lot of good companies that can help you do it. What is the future of the ZigBee Alliance? What are some of your goals? It’s pretty much what it has been in the past, except now we are in the mode of where the standards now are in very wide deployment around the world, particularly in the smart energy arena, which is not a static arena. The way the wireless sensor networks has been unfolding, eventually there will be enough

INTERVIEW

“The challenges for smart energy is making people comfortable in the early market phase, that this technology is not just a flash in the pan, but it will be around for years to come, because that’s the lifetime of these designs.” market vertical that they will knit together in sort of a seamless internet of things, but that’s not the case now. It’s been easier for the marketplace to work at home automation, remote controls, retail and energy, so now we have ten of those verticals and there’s more coming. It’s a very active area as companies look at how they can benefit from growing a particular segment, by having a common application as well as a common network. That job is not done, and we’ll continue at that for quite some time. Meanwhile, as we

gain more and more experience, there’s additional features and additional capabilities that we want, and we’ve just added one called ZigBee Light Link, which is really aimed at the do-it-yourself or general purpose consumer marketplace. It has very integrated communications inside and you’ll be able to create very simple in-home lighting networks with no computer required. Over the next several years, we’ll see expansion of these systems and they’ll gradually merge into a seamless and completely

ubiquitous internet of things, but it’s going to take a lot of work and additional standards, gateways and bridges before we get the systems worked out.

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Capacitiv Sensors with Auto-Calibration for Human Touch Interfaces Emmanuel T. Nana NXP Semiconductors

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TECH ARTICLE

One popular way to use capacitive sensors is to replace mechanical switches. There are fewer parts involved, which saves cost and increases reliability, and the novelty of proximity/touch interfaces can make the end product more desirable. For example, the proximity feature can be used in cell phones and anti-tampering devices, to detect when the equipment is close to an object or not. Touchfree operation is also useful in environments that use hazardous or explosive materials, since no contact is required, and in medical applications, because the user can still control the system while wearing surgical gloves, and thus maintain a sanitary environment. Proximity sensing also benefits hermetically sealed applications, since the sensor works with dielectric material sandwiched between two electrodes. One drawback of proximity sensors, however, is the trouble they have compensating for changes in the environment over time. Changes in humidity, for example, dirt collecting on the sensor area, or a change in the moving object can impact sensitivity and reduce performance. NXP Semiconductors is taking a new approach that lets the sensor adjust itself continuously to the environment. NXPâ&#x20AC;&#x2122;s PCF8883, PCA8885, PCF8885, and PCA8886 capacitive sensors use a patented auto-calibration technology to detect changes in capacitance. The devices digitally filter out very slow and very quick changes in capacitance at the input. As a result, the performance of the NXP devices is less affected by conditions that can impair or prevent correct functions in other devices. With auto-calibration, such things as dirt, humidity, freezing temperatures, or damage to the electrode do not affect the device function.

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Theory of Operation The device has two resistor-capacitor (RC) timing circuits. The first is connected to the IN pin, which connects to the external sensing plate, and the second is used as a reference. The discharge time (tdch) of the input RC timing circuit is co pared to the discharge time (tdch(ref)) of the reference RC timing circuit. Both RC timing circuits are periodically charged from VDD(INTREGD) via identical synchronized switches and then discharged via a resistor to ground (VSS). The charge-discharge cycle is governed by the sampling rate (fs). If the voltage of one of the RC timing circuits falls below the internal reference voltage Vref, the respective comparator output will become LOW. The logic following the comparators determines which comparator switches first. If the upper (reference) comparator switches first, then a pulse is given on CUP to count up. If the lower (input) comparator switches first, then a pulse is given on CDN to count down. The pulses control the charge on the external capacitor, CCPC, on CPC pin. Every time a pulse is given on CUP, CCPC capacitor is charged from VDD(INTREGD) for a fixed time, causing the vol age on CCPC to rise. Likewise, when a pulse occurs on CDN, CCPC capacitor is connected to a current sink to ground for a fixed time, causing the voltage on CCPC to fall. If the capacitance on the IN pin increases, the tdch discharge time increases and it will take longer for the voltage on the corresponding comparator to drop below Vref. Only once this happens does the comparator output become LOW, with the result that a pulse on CDN slightly discharges the external CCPC capacitor. Thus most pulses will now be given by CUP. Without further action, CCPC capacitor would then fully charge. However, the auto-calibration mechanism, which is based on a voltagecontrolled sink current (Isink) connected to the IN pin, attempts to equalize the tdch discharge time with the tdch(ref) internal reference discharge time.

Figure 1: Functional diagram of capacitive sensor PCF8883

the voltage on CCPC is rising, thereby compensating for the increase in capacitance on the IN pin. This arrangement constitutes a closed-loop control system that constantly attempts to equalize tdch with tdch(ref). This allows compensating for slow changes in capacitance on the IN pin. Fast changes, due to an approaching hand, for example, will not be compensated. In the equilibrium state, the discharge times are equal and the pulses alternate between CUP and CDN. From this also follows that an increase in capacitor value CCPC results in a smaller voltage change per pulse CUP or CDN. As a result, the compensation due to internal Isink current is slower, and the sensitivity of the sensor will increase. Similarly, a decrease in CCPC capacitor will result in a lower sensitivity. Following the sensor logic depicted in Figure 1, the counter counts the pulses of CUP or CDN respectively. The device only switches its output when the capacitance changes more than 63 times consecutively in one direction. Very slow changes are neutralized. and extremely quick changes donâ&#x20AC;&#x2122;t register because the device never reaches the required number of changes for a switch. The counter is reset every time the pulse sequence changes from CUP to CDN or vice versa.

The current source is controlled by the voltage on Sample Application CCPC, which causes the capacitance on the IN The sensing plate is connected to a coaxial cable, pin to be discharged more quickly in the case that which is in turn connected to the IN pin. (The sens-

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ing plate can also be connected directly to the IN pin.) An internal low-pass filter is used to reduce RF interference. For added RF immunity, an additional low-pass filter, consisting of a resistor RF and a capacitor CF, can be added to the input. Resistor RC reduces the discharge time such that the internal timing requirements are fulfilled by assisting the internal current sink. RC is only required for larger sensor capacitances. Sensitivity and response time are the two primary items to take into account when fine-tuning switch performance. In this next section, we look at these two factors and make recommendations for optimizing the design. Sensitivity If the sensitivity is increased, the possibility of incorrect switching due to interference from electrical fields also increases. This has a strong influence on the switching characteristics and may be compensated by reducing the sensor area. On the other hand, increasing the sensitivity lets the sensor react at a longer distance, and improves the range through materials with different permittivity. Approach speed and dynamics

requires more than 63 consecutive increases (or decreases) in capacitance over a fixed period to cause a switch at the output. The first switch occurs when the sensor can no longer compensate the change in capacitance. A triggering object, moving at a constant speed, will cause a greater change in capacitance as it approaches the sensing plate. As the approach speed increases, the required distance from the switch increases as well. If the distance between the sensor plate and the triggering object is larger than the sensor plate area, then a certain amount of fine-tuning may be required. Area of the sensor plate The size and form of the sensor plate can be varied to obtain optimal switching behavior or to conform to the size constraints of the application. Oval and round areas are usually best, since they present the fewest edge effects, but there is considerable flexibility in sensor design. In keyboards, the keys typically have a relatively small surface area. In this case, the sensor area needs to be roughly comparable to the size of a fingertip, and the switch must be fine-tuned such that neighboring switches donâ&#x20AC;&#x2122;t react in error.

The sensor compensates for changes in static or The capacitance is proportional to the cross-secslowly changing capacitance. As mentioned above, tional area of the sensing plate. In most cases, the autocalibration feature means that the sensor simply increasing the sensing area will lead to an

Figure 2: Typical connections for a general application

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EEWeb PULSE improvement in sensitivity. When the sensing area is limited by the application, the value of CCPC capacitor has to be increased to increase the sensitivity.

pling frequency and therefore the reaction time of the switch. Figure 5 shows that smaller values of CCLIN correspond to faster reaction times.

The sensor reacts more quickly when the frequency Using a bigger triggering object can also increase is increased, since the necessary number of comsensitivity. This may prove useful in certain applica- parisons is reached in less time. This also means tions, such as when switching through a thick layer that the sensor self-calibrates to new environments of material where the material itself influences the more quickly, with the result that a slow-moving sensitivity. hand will no longer cause the sensor to switch. That is, the sensor calibrates itself to the new enviThickness and nature of the dielectric ronment (with the hand present) more quickly than it detects the changes caused by the approaching The dielectric encompasses everything between hand. Another consequence of increasing the samthe sensing area and the triggering object area. pling frequency is that the sensor reacts to quick The thickness and nature of each dielectric influchanges at a distance with higher sensitivity. This ences the strength and flux of the electrical field effect can be enhanced by increasing CCPC or the passing through. The electrical field will be refractsensing area. ed, diffracted, reflected, or diminished depending on the exact materials used, and on the thickness To get the proper dimension of CCLIN, it’s imporof the construction. tant to know the normal approach speed of the triggering object. For example, a machine may move Materials having higher relative permittivity supfaster than a human does, and a single finger can port higher sensitivity because the electrical field often move more quickly than an entire hand. strength is proportional to the relative permittivity, and inverse proportional to the thickness. An exIt’s important to keep in mind that increasing the ample is a sensor area mounted behind 10 mm of response time (and thereby reducing the switching glass, a 0.3 mm air gap, and 2 mm of plastic. The frequency) reduces power consumption. As shown air gap is an issue, since its relative permittivity is in figure 6, the higher sampling frequencies associlow compared to the plastic and glass. Therefore, ated with shorter reaction times lead to increased air gaps should be minimized and the thickness of current consumption, and that uses more energy. the material should be reduced to a minimum. By Depending on the application, the designer has to placing conductive foam between the sensor plate find the best trade-off between speed and power and the glass, the air gap can be avoided comconsumption. pletely. Plate (electrode) orientation The more field lines that the triggering object cuts, the larger the generated capacitance change will be. For instance, an approaching palm area triggers a switch faster than the side of the hand. For this reason, it’s important to position the sensing plate in a way that makes it easy for the user’s natural touch or proximity motion to trigger a change. Response Time The value of the CCLIN capacitance connected on the CLIN pin determines the internal sam-

Other Considerations for Power Consumption The capacitive sensors from NXP offer very low power consumption. The single-channel PCF8883 consumes less than 5 μA, even under worst-case conditions. Supply voltage and temperature also have an impact on power consumption. NXP’s devices support a wide range of supply voltages (from 2.8 to 9 V), and offer low current consumption at lower supply voltages (see Figure 7).

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Figure 5: Switching time (tsw) with respect to capacitor on pin CLIN (CCLIN)

Figure 7: IDD with respect to VDD (PCF8883)

Figure 6: IDD with respect to sampling frequency (fs)

Figure 8: IDD with respect to temperature (PCF8883)

Figure 8 shows that more power is required to drive the devices at low temperatures.

NXP Semiconductors, with its PCF8883, PCA8885, PCF8885, and PCA8886 capacitive sensors, takes advantage of a patented auto-calibration feature that improves reliability. Designing with auto-calibration requires a certain amount of fine-tuning, since the switch has to be optimized for typical application requirements, but once the initial configuration is set, the sensor offers enhanced performance and longevity. As a result, these auto-calibrating devices are expanding the reach of capacitive sensors, and bringing a new level of user friendliness to a wider range of applications.

Conclusion By enabling human interfaces that can be controlled by proximity or touch, capacitive sensors have the ability to transform the way we interact with electronic systems. Until now, a limiting factor has been reliability, since environmental factors such as humidity, dirt, freezing temperatures, and changes in the moving object can have a negative impact on sensitivity and responsiveness.

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AWind transformer is usually installed at the energy bottom and of reliable AC power. The switching of these devices is turbine power is used to convert kinetic the tower to provide voltage conversion from the low usually DSP-embedded into electrical energy through the use of a generator. As and reliablecontrolled AC power.by Thea switching of thesecontroller devices isvia Wind turbine power is used to convert kinetic energy FiberaOptic Turbine Blade and fiber optic link, to provide efficient reliable switching windelectrical conditions vary,through the created from voltage generated by electrical thethewind to medium/ controlled byWind a DSP-embedded controller via a into energy useenergy ofturbine, a generator. As usually control high galvanic isolation capability. the generator needs to electrical be converted usability. optic with link, to provide efficient and reliable switching wind conditionsfor vary, the energyfor created from A fiber high voltage transmission.

Inverte DC–AC Fiber Optic

Control Board and rectifi er, inverter, transformer and filter are within the generator needs to be converted for needed usability. A control with high galvanic isolation capability. There are numerous rectifier and inverter control switches the wind turbinetransformer for utility-grade ACare power to be transCommunication rectifi er, inverter, and filter needed within Rectifier and Inverter available: There are numerous rectifier and inverter control switches mitted over long distances (FigureAC 1).power to be transthe wind turbine for utility-grade available: mitted over long distances (Figure 1). • Insulated Gate Bipolar Transistor (IGBT) A transformer usually installed thecomponents bottom of thein the The rectifi er isand inverter are at key • Gate Bipolar Transistor (IGBT) •Insulated Gate Turn Off Thyristor (GTO) A transformer is usually at the the tower to provide voltageinstalled conversion frombottom theconverts lowofvoltage wind turbine system. The rectifi er noisy • Gate Turn Off Thyristor (GTO) tower to provide conversion the low voltage generated by thevoltage wind turbine, to from medium/high voltage • Integrated Gate Commutated Thyristor (IGCT) AC powerbytotheDC power, the inverter converts generated wind turbine,while to medium/high voltage Fiber Optic • •Integrated Gate Commutated Thyristor (IGCT) for transmission. Symmetrical Gate Commutated Thyristor (SGCT) for transmission. DC power to clean and reliable AC power. The • Symmetrical Gate Commutated Thyristor (SGCT) • Emitter Turn Off Thyristor (ETO) Rectiﬁer andof Inverter switching these devices is usually controlled • by Emitter Turn Off Thyristor (ETO) Rectiﬁer and Inverter Turbine Control Fiber optic components are commonly used to control a rectifier and inverter are key components the wind aThe DSP-embedded controller via a fiberinoptic link, to optic Fiber components are commonly used to control a Unit (TCU) The rectifi er and inverter are key components in the wind high voltage and current switching device, with reliable turbine system. The and rectifireliable er converts noisy AC power to with provide effi cient switching control high voltage and current switching device, with reliable turbine system. The rectifi er converts noisy AC power to control and feedback signals (Figures 2 and 3). DC power, while the inverter converts DC power to clean control and feedback signals (Figures 2 and 3). DC power, while the invertercapability. converts DC power to clean high galvanic isolation

Figure 1. Wind Turbine Power Generation Block Diagram

POF POF

Versatile Link Versatile Link HFBR-0500Z series HFBR-0500Z series

There are numerous rectifier and inverter control switches available:

Driver Logic Driver Logic andand Protection Protection Functions Functions

ControlBoard Board Control VersatileLink Link Versatile HFBR-0500Zseries series HFBR-0500Z

C Rg Rg

Driver Driver

• Insulated Gate Bipolar Transistor

IGBT IGBT(IGBT)

• Gate Turn Off Thyristor (GTO)

Gate Driver Gate Driver

• Integrated Gate Commutated Thyristor (IGCT)

Figure Figure 2. 2.IGBT IGBTGate GateDriver DriverBlock BlockDiagram Diagram

• Symmetrical Gate Thyristor (SGCT)

V+ V+ ETOpETOp Over OverCurrent Current Protection Protection

PWM PWM Command Command

Dp Dp

GateGate Driver Driver

ETOn ETOn

Gate DriverGate Driver

Controller Controller

V– Versatile Link HFBR-0500Z Versatileseries Link HFBR-0500Z series

V–

Versatile Link HFBR-0500Z series Versatile Link HFBR-0500Z series

Figure 3. ETO Two-Level Voltage Source Converter Phase Leg Block Diagram Figure 3. ETO Two-Level Voltage Source Converter Phase Leg Block Diagram

22 2 2

Commutated

• Emitter Turn Off Thyristor (ETO) Fiber optic components are commonly used to control a high voltage and current switching device, with reliable control and feedback signals (Figures 2 and 3).

POF POF

Current Current Control Control

•

EEWeb | Electrical Engineering Community

Condition Monitoring System Most modern wind turbines have intelligent features to monitor and control the system to accommodate varying wind conditions. For example, atmospheric sensors detect wind speed and direction. Other sensors monitor

HFBR-1528Z

650 nm, Transmitter

DC – 10 MBd

Condition monitoring systems AFBR-1624Z, AFBR-1629Z 650 nm, Transmitter

DC – 50 MBd

HFBR-2528Z

Wind farm networking

er C

3 Phase Line Filter and Transformer

Utility Grade AC Power

AFBR-2624Z, AFBR-2529Z

40 m

300

TECH ARTICLE 50 m

650 nm, Receiver

* Optical link distance varies with data rate. rate allows opticalPOF link distance. the condition and strength of operating the using fi Lower ber data optics canlonger utilize (plastic optical HCS is a registered trademark of OFS turbine’s parts to avoid run-to- fiber) and Avago Technologies’ HFBR-0500Z products. failure. Designers can select from connectors with snap-in, Condition Monitoring System latching, and screw-in designs. Avago Technologies’ Wind turbines needwind to withstand Most modern turbines haveversatile intelligentlink features to products. select from connec sub-family allowsDesigners fi eld can connector andconditions, control the system accommodate varying snap-in, latching, and screw-in designs. Avago extrememonitor weather such tocapabilities for POF and the associated connectors, windand conditions. example, atmospheric sensors gies’ versatile link sub-family allows field conne as storms lightning.For In these allowing for field repairs,bilities maintenance, and installation. detect speed and direction. Other sensors monitor for POF and the associated connectors conditions, it iswind important to ensure the condition and strength of the turbine’s parts to avoid field repairs, maintenance, and installation. that the turbine’s monitoring Besides good isolationforproperties, these products run-to-failure. Besides good isolation properties, these system is designed to provide provide excellent signal integrity as they are immune Wind turbines need to withstand extreme weather condiprovide excellent signal integrity high voltage and current isolation. to electro-magnetic interference (EMI). They are an as they are tions, such as storms and lightning. In these conditions, to electro-magnetic interference (EMI). The Fiber optics becomes a preferred excellent solution for monitoring system communications it is important to ensure that the turbine’s monitoring excellent solution for monitoring system co choice system of medium as itto off ers high overvoltage long and distances reliable datadistances transmission in is designed provide currentwithtions over long with reliable data tra much higher voltage and current high voltage/current applications. isolation. Fiber optics becomes a preferred choice of in high voltage/current applications. isolationmedium properties compared as it off ers much to higher voltage and current For greater ESD and EMI protection, Avago Tec greaterandESD isolation properties optocouplers other and EMI protection, Avago optocouplers and othercompared similar to For HFBR-0506AMZ ers a metalized packa Technologies’ HFBR-0506AMZ series offseries ers aoff metalized similar components. components. provides excellent shielding. The SMA-styled packaging that provides excellent shielding. The SMAIn the nacelle of the wind turbine (Figure 4), short link also works well in areas with vibration and m In the nacelle the wind styled connector also works well in areas with vibration distancesof using fiberturbine optics can utilize POF (plastic shocks. (Figure optical 4), short link distances and mechanical shocks. fiber) and Avago Technologies’ HFBR-0500Z

Figure 4. Elements within a Wind Turbine Nacelle Requiring Fiber Communications

Wind Turbine Development: Location of Manufacturing Activity, S. George and S. Matt, “Renewable Energy Policy Project”, September 20

Table 1. Common Avago Technologies’ Fiber Optic Components Part Numbers 3

Part Numbers

Description

HFBR-1521ETZ

650 nm, Transmitter

HFBR-2521ETZ

650 nm, Receiver

HFBR-1522ETZ

650 nm, Transmitter

HFBR-2522ETZ

650 nm, Receiver

HFBR-1528Z

650 nm, Transmitter

HFBR-2528Z

650 nm, Receiver

AFBR-1624Z, AFBR-1629Z

650 nm, Transmitter

AFBR-2624Z, AFBR-2529Z

650 nm, Receiver

Data Rate

Distance* POF (1mm)

DC – 5 MBd

20 m

DC – 1 MBd

43 m

DC – 10 MBd

40 m

DC – 50 MBd

50 m

HCS® (200μm)

300 m

* Optical link distance varies with operating data rate. Lower data rate allows longer optical link distance. HCS is a registered trademark of OFS

Condition Monitoring System Most modern wind turbines have intelligent features to

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products. Designers can select from connectors with

EEWeb PULSE

g systems, individual HCS (hardonger link be needed 0meters in eater resisd are lightcal cabling

Data Acquisition System Controller

hread and es. The HFmulti-mode k distance commonly tance wind

fiber optic nd turbine ns.

which have needs over Computer System

Server Network Switch

Switch CONTROL CENTRE

Figure 5. Wind Farming Configuration

| Electrical Engineering Community 24 Part EEWeb omponents Numbers

Switch

Switch CONTROL CENTRE

Distance* TECH ARTICLE Figure 5. Wind Farming Configuration

mitter

Data Rate

POF (1mm)

DC – 50 MBd

50 m

Description

eiver

AFBR-1624Z, AFBR-1629Z

650 nm, Transmitter

eiver

AFBR-2624Z, AFBR-2529Z AFBR-5978Z 125

650 nm, Receiver

mitter

ver

ceiver

62.5um/125um

Table 2. Common Avago Technologies Fiber Optic Components Part Numbers Part Numbers

mitter

HCS® (200μm)

125 MBd

MBd

50 m

Data Rate

POF (1mm)

DC – 50 MBd

50 m

100 m

650 nm, Transceiver 50 m

125 MBd

AFBR-5972Z

650 nm, Transceiver

125 MBd

HFBR-14X4Z

820 nm, Transmitter

160 MBd

HFBR-24X6Z

820 nm, Receiver

HFBR-1312TZ

1300 nm, Transmitter

160 MBd

HFBR-57E5APZ

1300 nm, Transceiver

125/155 MBd

160 MBd

160 MBd HFBR-2316TZ

1300 nm, Receiver

Distance*

62.5um/125um

50 m

100 m

50 m

500 m -

2 km

500 m 2 km 2 km

* Optical link distance varies with operating data rate. Lower data rate allows longer optical link distance. HCS is a registered trademark of OFS

125/155 MBd

HCS® (200μm)

2 km

e. Lower data rate allows longer optical link distance.

Wind Farmplease Networking For more information and a complete list of distributors, For productTurbine information and aand completeWind list of distributors, go to our web site: www.avagotech.com please go to Avago’s website: Avago, Avago Technologies, and the are trademarks of Avago Technologies, Limited in the United States and other countries. Data collected from theA logo condition monitoring systems, Data subject change. Copyright © 2007-2012 Technologies Limited. All rights reserved. with the touse of short-link POF Avago fi ber links in individual AV02-0732EN - July 26, 2012 wind turbines, are typically multiplexed into HCS or multi-mode fi ber cables. The se go to our(hardclad web site: silica) www.avagotech.com longer link distances of HCS and multi-mode fi ber may be needed if wind turbine towers are greater than vago Technologies, Limited in the United States and 100meters in height. Fiber cables are other both countries. robust, off er greater resistance to harsh environmental elements, ogies Limited. All rights reserved. and are lightweight. All of these are requirements for vertical cabling in wind turbine towers.

www.avagotech.com

Industry standard connectors like the ST/ST-thread and SMA are all available from Avago Technologies. The HFBR-0400Z series operates over both HCS and multimode fiber, which off er greater bandwidth and link distance compared to the POF solution. These parts are commonly used in wind turbine towers and over long distance wind farm networks. Avago Technologies has developed a series of fi ber optic transmitters, receivers, and transceivers for wind turbine monitoring systems and networking applications and offers parts from 650nm, 820nm, or 1300nm, which have data rates up to 160MBd to meet customer needs over various link distances.

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