**3.5.5 Installation of sensors and results**

The HEP chosen for this experiment was the UHE-Samuel, at Brazil`s far west city of Porto Velho, close to the border with Bolivia. UHE-Samuel is located at the Jamari River, a tributary of the Madeira River, which in turn, is one of the major tributaries of the Amazon River. The UHE-Samuel generates 216 MW and counts with five Kaplan-type turbines generating each one about 42 MW.

The system began to be installed in the generator number five in November 2007. This process was performed in two opportunities: during a five-day shutdown of the machine for maintenance and in another five-day window for retrofit (exchange of rectifiers).

For the installation of the sensors inside the stator it is obviously necessary to turn off the machine, which is not an easy task. This is because, as the majority of HEPs in Brazil, UHE-Samuel is a national-grid-connected HEP therefore to be turned off, one needs a special authorization issued by the National System Operator. The request is normally dispatched six months in advance, and if granted, the machine is allowed to be turned off during a fiveday window.

The machine, which operates at a normal temperature around 95oC, needs 24 hours to drop its temperature to about 45oC in order to be possible to enter inside the stator hall to install the sensors. The stator environment can be considered to be one of the worst places a sensor can be installed in. Its average temperature is about 95oC peaking up to 110oC with an air humidity close to 100%; it presents a dense oily atmosphere; a very high electro-magnetic interference at a few millimeters from 15 kV conductors carrying a current of 2 kA; vibrations of every kind up to 0.3 G and among heavy parts that are frequently assembled and disassembled using heavy tools with huge force. How can so a fragile sensor, such as a 125-µm-diameter-glass-optical-fiber-sensor, be installed in such harsh environment and even though keep its reliability during the expected 40-years life span?

A FBG used as a temperature sensor presents a very small time constant because it has a small mass. In order to protect this sensor and do not deteriorate such a valuable parameter the sensor was installed loosely inside a thin U-form copper tubing in order to allow a good heat transfer between the cooling air and the optical fiber, as shown in Fig. 3.5.4. The tubing, which also protects the fiber against strain, goes out and back again from an IP65 polymeric enclosure.

Fig. 3.5.4. Box containing the fiber-optic splices with the FBG inside the U-shape copper tubing (left) and installed inside the generator (right).

An adequate fiber-optic cable connected all six boxes as they were installed around the stator winding behind of each radiator of the generator. The optical cable was then placed

The HEP chosen for this experiment was the UHE-Samuel, at Brazil`s far west city of Porto Velho, close to the border with Bolivia. UHE-Samuel is located at the Jamari River, a tributary of the Madeira River, which in turn, is one of the major tributaries of the Amazon River. The UHE-Samuel generates 216 MW and counts with five Kaplan-type turbines

The system began to be installed in the generator number five in November 2007. This process was performed in two opportunities: during a five-day shutdown of the machine for

For the installation of the sensors inside the stator it is obviously necessary to turn off the machine, which is not an easy task. This is because, as the majority of HEPs in Brazil, UHE-Samuel is a national-grid-connected HEP therefore to be turned off, one needs a special authorization issued by the National System Operator. The request is normally dispatched six months in advance, and if granted, the machine is allowed to be turned off during a five-

The machine, which operates at a normal temperature around 95oC, needs 24 hours to drop its temperature to about 45oC in order to be possible to enter inside the stator hall to install the sensors. The stator environment can be considered to be one of the worst places a sensor can be installed in. Its average temperature is about 95oC peaking up to 110oC with an air humidity close to 100%; it presents a dense oily atmosphere; a very high electro-magnetic interference at a few millimeters from 15 kV conductors carrying a current of 2 kA; vibrations of every kind up to 0.3 G and among heavy parts that are frequently assembled and disassembled using heavy tools with huge force. How can so a fragile sensor, such as a 125-µm-diameter-glass-optical-fiber-sensor, be installed in such harsh environment and

A FBG used as a temperature sensor presents a very small time constant because it has a small mass. In order to protect this sensor and do not deteriorate such a valuable parameter the sensor was installed loosely inside a thin U-form copper tubing in order to allow a good heat transfer between the cooling air and the optical fiber, as shown in Fig. 3.5.4. The tubing, which also protects the fiber against strain, goes out and back again from an IP65 polymeric

Fig. 3.5.4. Box containing the fiber-optic splices with the FBG inside the U-shape copper

An adequate fiber-optic cable connected all six boxes as they were installed around the stator winding behind of each radiator of the generator. The optical cable was then placed

tubing (left) and installed inside the generator (right).

maintenance and in another five-day window for retrofit (exchange of rectifiers).

even though keep its reliability during the expected 40-years life span?

**3.5.5 Installation of sensors and results** 

generating each one about 42 MW.

day window.

enclosure.

within the existing cable trays along with other electric cables following all the way up, from the generator to the HEP control room where the optical interrogator and an industrial PC were installed.

The optical interrogation setup consists of a broad band optical source that illuminates all FBGs in the array. The return signal of each FBG is detected by an optical spectrum analyzer (OSA) that identifies the center wavelength of each FBG reflection pulse. The OSA communicates with an industrial PC via RS-232 interface, running a LabView software for calculation and storage of the temperatures. The PC publishes all data into the company's Intranet that automatically and instantaneously become available to the HEP central software control. Fig. 3.5.5 shows the block diagram of the system.

However, the proposed system goes much further in ambition. After the approval of the current system, the proposed project planes to use this technology to fulfill all temperature needs of the HEP, including turbines, air, oil and water ducts and other electrical equipment as well at the substation (see Fig. 3.5.6). Since a single optical fiber cable can monitor about 16 or more sensors, it is just necessary one cable per equipment for all temperature measurements. The system is also intended to access the Internet so as to be able to be accessed remotely, even from another location. This is especially advantageous for automatic unmanned substations.

Fig. 3.5.5. Depiction of a cross-section of the hydro-generator (left). Generator in detail with sensors connected to the interrogation system (right).1 to 6) FBG sensors; 7) Radiator; 8) Stator; 9) Machine room; 10) Bearing; 11) Kaplan turbine.

Shortly after the installation we noticed that the last two FBGs in the fiber-optic cable were not identified by the optical interrogator, probably due a malfunction of the optical connectors. But there was no time to open up again the inspection windows of the stator as the machine was programmed to start up immediately. Since then, the machine did not stop again as our requests for shutting down were not granted so far. Currently, at the time of writing this article, the machine is in operation for two and a half years and the fiber-optic system is monitoring normally four radiators. The results of the measurements are sent periodically to the company's head-quarters in Belém, some 1,800 km north and from there to our laboratory located in Rio de Janeiro, 2,400 km south.

Optical Fiber Sensors 37

Fig. 3.5.9 shows the temperature of the generator in normal operation. At this time the

As in Fig. 3.5.8, we can still observe in Fig. 3.5.9 a difference in temperature between different sections of the generator. For explaining this behavior it is necessary first to understand how the cooling system works. The cold water from the bottom of the dam is taken by a pipe and, after a chlorine treatment, it feeds the radiators, one after the other, in a row. But as the water pipe goes around the stator feeding each radiator, the water loses pressure so that the first radiator has a higher water flow than the second, and so on until the water reaches the last radiator which receives much less water. Therefore, each section of the stator is cooled down to different temperatures leading to the behavior observed in Fig. 3.5.8 and Fig. 3.5.9. Of course a load unbalance between the phases would also lead to different temperatures but in a 5-machine plant with all generators interconnected this

Fig. 3.5.8. Temperature evolution of generator 5 during start up.

generator was producing 22 MW with an average water flow of 82 m3/s.

Fig. 3.5.9. Temperature of generator 5 in operation.

would be very difficult to happen.

Fig. 3.5.6. Proposed extension of the system including all monitoring needs of the hydroelectric plant.

Just after the installation the system started the monitoring the temperatures, producing the graph shown in Fig. 3.5.7. We can observe all signals superimposed at about 33oC.

Fig. 3.5.7. Temperature of generator 5 before start up.

After the installation the machine was several times started up and down in test procedures. The graph in Fig. .45 shows the evolution of the temperature during the last start up test of the generator. Notice that, differently than in Figure 3.5.8, the temperatures of the radiators were not the same before start up. This is because the machine was working before with differenttemperatures around the stator, which is normal as it will be seen later. At 9 AM the turbine was opened to the dam and the machine started-up. The temperature at FBG 3 rose from around 35oC to 85oC while the turbine accelerated up to 90 rpm until in phase with the 60 Hz grid frequency. Then, at 6 PM the generator was switched to the national grid and the temperature rose again up to 95oC, stabilizing thereafter.

Fig. 3.5.6. Proposed extension of the system including all monitoring needs of the hydro-

graph shown in Fig. 3.5.7. We can observe all signals superimposed at about 33oC.

Fig. 3.5.7. Temperature of generator 5 before start up.

grid and the temperature rose again up to 95oC, stabilizing thereafter.

Just after the installation the system started the monitoring the temperatures, producing the

After the installation the machine was several times started up and down in test procedures. The graph in Fig. .45 shows the evolution of the temperature during the last start up test of the generator. Notice that, differently than in Figure 3.5.8, the temperatures of the radiators were not the same before start up. This is because the machine was working before with differenttemperatures around the stator, which is normal as it will be seen later. At 9 AM the turbine was opened to the dam and the machine started-up. The temperature at FBG 3 rose from around 35oC to 85oC while the turbine accelerated up to 90 rpm until in phase with the 60 Hz grid frequency. Then, at 6 PM the generator was switched to the national

electric plant.

Fig. 3.5.8. Temperature evolution of generator 5 during start up.

Fig. 3.5.9 shows the temperature of the generator in normal operation. At this time the generator was producing 22 MW with an average water flow of 82 m3/s.

Fig. 3.5.9. Temperature of generator 5 in operation.

As in Fig. 3.5.8, we can still observe in Fig. 3.5.9 a difference in temperature between different sections of the generator. For explaining this behavior it is necessary first to understand how the cooling system works. The cold water from the bottom of the dam is taken by a pipe and, after a chlorine treatment, it feeds the radiators, one after the other, in a row. But as the water pipe goes around the stator feeding each radiator, the water loses pressure so that the first radiator has a higher water flow than the second, and so on until the water reaches the last radiator which receives much less water. Therefore, each section of the stator is cooled down to different temperatures leading to the behavior observed in Fig. 3.5.8 and Fig. 3.5.9. Of course a load unbalance between the phases would also lead to different temperatures but in a 5-machine plant with all generators interconnected this would be very difficult to happen.

Optical Fiber Sensors 39

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Observing Fig. 3.5.9 it is possible to notice that, even in steady state the generator temperatures vary along the time, with all temperatures following the same pattern. This is how the generator responds to the energy demands by the load.

#### **3.5.6 Conclusions**

This case described the world's first real application, test and operation of a FBG temperature sensor array inside a fully operational and connected-to-the-grid hydro-electric power generator. The FBGs sensors were installed inside the generator in November 2007 and are in continuous operation since then. The system was capable to measure and monitor reliably and accurately temperatures inside the generator even considering the harsh environment of the stator generator.

With this system in operation a large reduction of installation and maintenance costs could be avoided since many kilometers of electric wire would be saved.

Another conclusion of such experiment is that it is very difficult to conciliate research and commercial interests. Scientists working with power generation find enormous difficulties in having machines turned off, particularly those connected to the national grid. Power operation authorities are so much concerned about system reliability and energy production without discontinuities that often refuse any kind of research proposals that could, in any way, put in jeopardy machines integrity or interrupt energy production.

#### **4. References**


Observing Fig. 3.5.9 it is possible to notice that, even in steady state the generator temperatures vary along the time, with all temperatures following the same pattern. This is

This case described the world's first real application, test and operation of a FBG temperature sensor array inside a fully operational and connected-to-the-grid hydro-electric power generator. The FBGs sensors were installed inside the generator in November 2007 and are in continuous operation since then. The system was capable to measure and monitor reliably and accurately temperatures inside the generator even considering the harsh

With this system in operation a large reduction of installation and maintenance costs could

Another conclusion of such experiment is that it is very difficult to conciliate research and commercial interests. Scientists working with power generation find enormous difficulties in having machines turned off, particularly those connected to the national grid. Power operation authorities are so much concerned about system reliability and energy production without discontinuities that often refuse any kind of research proposals that could, in any

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**3.5.6 Conclusions** 

**4. References** 

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environment of the stator generator.


**2** 

**Communication Strategies for Various** 

Jin-Ho Cho and Sang Hyo Woo

*Kyungbook National University,* 

*South Korea* 

*School of Electrical Engineering and Computer Science,* 

**Types of Swallowable Telemetry Capsules** 

In this chapter, introducing some of the ideas, potentialities, and limitations of swalowable telemetry capsule systems. The telemetry systems were widely used for animal research while the subject can do its regular activities [1-9]. Therefore, it is an ideal method to collect the data of migration path and environmental data. In order to collect the data, the telemetry system has to be attached or implanted to the subjects and transmits the signal throughout the antenna. For the human patients, most of physiological signal from outside of the body did not need telemetry systems, because the signal was easily distorted when the patients were moving. Therefore, the telemetry systems are used when the device is implant into the patients and then collect the data. Since the implantation of the device is extremely difficult work, using the telemetry system is limited for scientific researches and a commercial

Since the implantable telemetry systems is limited by the regulations and safety issue, the scientists look forward to develop a disposable capsule that resemble a medical pill and automatically measure the various philological data after swallow it. There are many frontier researches about the telemetry capsules. Some of the capsule measured the intraluminal pressure from inside of the gastro intestine while the capsule goes naturally flow toward to aboral direction [10-14]. Since the physician gets the intraluminal data, it was hard to assume a

Another capsule can measure pH signals from the gastro intestine. This capsule provides the meaningful data to diagnosis many diseases such as the gastroesophageal reflux. These capsules also measure the pH signal while it is naturally flow and does not provide location information. While most of the capsules was measuring the signal when the capsule was naturally flow toward to aboral direction, a bravo capsule can stop at the esophagus and measuring the pH difference [15-19]. Other capsules measures the core temperature [20, 21],

Unlike above applications, a capsule endoscopy is a revolutionary product that captures inside of the gastro images and transmits it throughout the RF transmitter [22-26]. In order to get clear images, the data rate of the RF transmitter has to be sufficiently high while the power consumption is still low that could be active by small coin batteries. The frontier of this field is Given Image company products and it could monitor not only the small intestine

location of the capsule such as the capsule is in the middle of a duodenum or jejunum?

**1. Introduction** 

medical telemetry device was not advent.

which is a bit higher than skin temperature.

but also the esophagus and colon.

