Development of temperature monitoring for HECON switchgears

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LAPPEENRANTA-LAHTI UNIVERSITY OF TECHNOLOGY LUT School of Energy Systems

Electrical Engineering

Sami Mattila

DEVELOPMENT OF TEMPERATURE MONITORING FOR HECON SWITCHGEARS

Examiners: Professor Juha Pyrhönen D.Sc. (Tech), Janne Nerg Supervisors: PhD, Marek Mägi

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ABSTRACT

Lappeenranta-Lahti University of Technology LUT School of Energy Systems

Electrical Engineering

Sami Mattila

Development of temperature monitoring for HECON switchgears

Master’s thesis 2021

112 pages, 73 figures, 6 tables, 13 appendices Examiners: Professor Juha Pyrhönen

D.Sc. (Tech.), Janne Nerg Supervisors: PhD, Marek Mägi

Keywords: temperature monitoring, switchgear, electrical cabinet

This thesis was done for Harju Elekter Group. The main goal of this thesis was to find a suitable wireless temperature monitoring system for Harju Elekter Groups own switchgear product family HECON. When a suitable system was found the next task was to do research of where and why temperature sensors should be installed. During this task, the preliminary design of sensor installation locations and data communication was developed. After this, testing of the system was done in Harju Elekter Elektrotehnika, Keila Estonia. System was tested on a HECON cabinet and the system was verified by comparing system results to results of another wired system and thermal camera. The final result of this thesis is a developed market ready option for HECON switchgears, where a wireless temperature monitoring system can be provided to customers. The results of the designing, testing and verification stages are presented in the thesis. This option for HECON switchgear product family will improve Harju Elekter Groups products, make product family more versatile and answer customer needs for electrical fire safety.

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TIIVISTELMÄ

Lappeenrannan-Lahden teknillinen yliopisto LUT LUT School of Energy Systems

Sähkötekniikka

Sami Mattila

HECON sähkökojeiston lämpötilanvalvonnan kehitys

Diplomityö 2021

112 sivua, 73 kuvaa, 6 taulukkoa, 13 liitettä Tarkastajat: Professori Juha Pyrhönen

TkT, Janne Nerg Ohjaajat: FT, Marek Mägi

Hakusanat: lämpötilan valvonta, kojeisto, sähkökeskus

Tämä lopputyö on tehty Harju Elekter Groupille. Tämän projektin päätavoite oli löytää sopiva langaton lämpötilanvalvontajärjestelmä Harju Elekter Groupin oman kojeistotuoteperheen HECON:lle. Kun sopiva järjestelmä oli löydetty, seuraava tehtävä oli tehdä selvitystyötä, minne ja miksi sensorit tulisi asentaa. Tämän selvityksen yhteydessä, luotiin alustavat suunnitelmat sensorien asennuspaikkojen ja datakommunikoinnin suhteen. Tämän jälkeen järjestelmä testattiin Harju Elekter Elektrotehnika:n tiloissa Keilassa Virossa. Järjestelmä testattiin testi – HECON sähkökeskuksen avulla ja järjestelmä verifioitiin vertaamalla sen tuloksia toisen langallisen lämpötilanmittausjärjestelmän ja lämpökameran tulosten kanssa. Tämän projektin lopputuloksena syntyi markkinavalmis valinnainen langaton lämpötilan valvontajärjestelmä HECON – tuoteperheelle, joka on suunniteltu, testattu ja tulokset on verifioitu. Tämä valinnainen lisävaruste HECON – keskus tuoteperheelle parantaa Harju Elekterin tuotteita, tekee tuoteperheestä monipuolisemman ja vastaa asiakkaiden tarpeisiin sähköpalo- turvallisuuteen liittyen.

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ACKNOWLEDGEMENTS

Studying in the university in parallel with a full-time job is very challenging. It would have never been possible without the support of other people. This thesis was started on autumn 2019 and was finished on spring 2021. The thesis was written in Pori and Ulvila, Finland, and tests were done in Keila, Estonia. Thesis was done calmly during a long period. Thinking afterwards, this was the right decision how to proceed.

I want to thank Jan Osa, CEO of Harju Elekter Oy. Jan was helping me to get started and provided resources for this project. I want to thank PhD, Marek Mägi, who was my supervisor from Harju Elekter Elektrotehnika. I had weekly meetings with Marek, when writing this thesis.

Marek gave me great advises and support during the whole project. I want to thank also electrical engineer Karl Kalmet from Harju Elekter Elektrotehnika, who was a great help for me during tests in Keila, Estonia. Karl was picking me up every morning from Keila train station and was running the tests with me with high motivation. I will remember my journey to Keila forever, it has been a pleasure to be your guest. I also like to thank Kalle Vuorio for the interview for this thesis.

Most of all, I want to thank my wife, Julia. She was the biggest support for me during my busy and harsh times of studying and working. My next goals after graduation are to be a great dad for our newborn child and to improve my skills as an electrical engineer.

Pori, Finland 30.3.2021 Sami Mattila

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NOMENCLATURE

Symbols

I Current

P Active power

R Resistance

U Voltage

Acronyms

ACB Air circuit breaker

ANSI American national standards institute CPU Central processing unit

DNP Distributed network protocol HMI Human-machine interface IDT Inter-digital transducers IP International protection code L1, L2, L3 Phases

LV Low voltage

MCB Miniature circuit breaker MCC Motor control centre

MCCB Moulded case circuit breaker

MV Medium voltage

HVAC Heating, ventilation and air conditioning IEC International Electrotechnical Commission

IR Infra-red

PC Personal computer PD Partial discharge PE Protective earth

PLC Programmable logic controller

RF Radio frequency

RCD Residual-current device RTU Remote terminal unit

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SAW Surface acoustic wave

SCADA Supervisory control and data acquisition TCP Transmission control protocol

USB Universal serial bus VSD Variable speed drive

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1 INTRODUCTION

1.1 Trends in the world and importance of temperature measurements

This thesis is written to present results of research and development of temperature measurements in industrial switchgears. Over the history of electrical cabinets and switchgears, the safety has become more and more important. Technology companies have invent more and more features, which are improving safety of switchgears. Customers are demanding increasingly safer solutions.

One safety element of switchgears is awareness of temperature occurring in the switchgear.

When electric current passes through conductors, there will always be also heat. In normal operation the heat is not a problem, when the design has been done correctly. Still there are always possibilities for spontaneous faults and problems during time. Sometimes evolving situations can be difficult to notice. Some situations can evolve very slowly and it is possible that evolving situations will be noticed too late. In case of temperatures, slowly evolving situations that are increasing temperatures, could not be noticed until fire, component breakdown or a fault in operation takes place. It is easy to understand, that customers would like to receive a notice of an evolving situation before a fault causes problems. In a case of fire, cost of repair can be high. Also unexpected stops in production can occur in case of temperature faults. The cost of stopped production can be extremely high even in short period of time. After all, the most important aspect is the safety of people and more and more has been done to improve safety of people. Industry companies want to provide a safe working environment to their personnel. (Alhainen, J. 2015).

Thermal imaging has become an important part of industry maintenance programs and a precautionary method to avoid hazardously evolved temperature faults (Vuorio. 2021). Thermal imaging is the most common method to inspect switchgears. Person with professional knowledge and skills can analyse switchgear very accurately and reliably (Sähköinfo. 2014).

However, this is still very much a manual work and as described before, trends in all areas of technology are to automate tasks. Companies are willing to reduce simple manual work of employees and let the machines and automation handle these tasks. Sometimes it is possible to

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11 fully complete certain tasks by machines and automation. Sometimes machines and automation can effectively help employee to complete tasks better and faster than without (Vessonen, I., Karvonen, H. 2019). Manufacturers have started to develop automatic temperature monitoring for switchgears and new ways to monitor temperatures in switchgears has appeared on the markets. Sensors and cameras can monitor temperatures continuously unlike an employee with a thermal camera. Data can be sent immediately to employees and different kind of alerts can be set to warn personnel of worsening situation. There are lot of benefits of automated surveillance, but it does not fully replace manual ways to monitor temperatures. Benefits of manual imaging are that a skilled person can analyse every visible point of switchgear and it is not reasonable to install sensors for all connection points of the switchgear. In today’s industry, it is reasonable to combine both methods, manual imaging and automated surveillance. This is how benefits of both methods are eliminating weaknesses of each other (Vuorio, 2021).

1.2 Different type of temperature sensors

Continuous surveillance of switchgear temperatures can be done in many ways. It is possible to build a system from different components. Many different types of temperature sensors can be found on the market. E.g., some with communication cables, other with different kinds of data handling units etc. Building a custom system by using components of different manufacturers is usually very time consuming and a challenging process. It will take a lot of time to design a reliable automated temperature monitoring system from single components.

That is why many manufacturers have started to provide ready solutions to customers. These solutions are including all the necessary components and designing. Also testing of the system has already done by the manufacturer. Technology for temperature monitoring can vary. Some manufacturers provide fibre wire connected sensors, which can be installed with a bolt connection. Also, infra-red solutions for temperature monitoring are one solution. This technology could be used for busbar monitoring. Wireless radio frequency (RF) temperature sensors are commonly used solutions in the switchgears because sensors could be installed in many different points in the switchgear. Also wiring is not needed because of wireless operation by RF signals. In this work, the interest is on wireless temperature monitoring systems for two reasons. The first reason is that these sensors are usually small and installation possibilities are good. These sensors are easy to install in many different points of the switchgear, unlike other

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12 solutions, which are usually designed for certain type of points. Wireless sensors are also faster to install compared to sensors with wires, because there is no wiring time required. Many temperature monitoring manufacturers are also nowadays focusing on wireless technology rather than wired to be able to provide more practical solutions. This is why market selection of wireless ready systems may be wider than the selection of wired systems.

1.3 Overview of Harju Elekter

As Harju Elekter is an Estonian stock company located in Keila. As Harju Elekter was founded in 1968 and it is operating in the sector of electricity, telecommunication and automation. As Harju Elekter has operations in four different countries.

In Estonia, As Harju Elekter owns two companies: As Harju Elekter Elektrotehnika and As Harju Elekter Teletehnika. As Harju Elekter Elektrotehnika is a manufacturer of electrical equipment for energy distribution, industrial and construction sectors. As Harju Elekter Teletehnika is a producer of sheet metal products and products for telecommunication and energy sector.

In Sweden, As Harju Elekter owns two companies: Sebab Ab and Grytek Ab. Sebab Ab is an engineering company for MV/LV power and distribution solutions for the construction, infrastructure and renewable energy sector. Grytek Ab is a manufacturer of prefabricated technical houses.

In Lithuania, As Harju Elekter own Harju Elekter UAB, which is engineering and contract manufacturing company for multidrive, MCC and power distribution systems.

In Finland, As Harju Elekter owns companies Harju Elekter Oy and Telesilta Oy. Harju Elekter Oy is a manufacturer of industrial electrical cabinets and prefabricated substations. Telesilta Oy is an electrical engineering company specialized in electrical contracting for shipbuilding industry (As Harju Elekter. 2021).

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13 1.4 Overview of HECON

HECON is a name for a switchgear product family of As Harju Elekter (Figure 1). It has been released to Finnish markets in 2019. HECON switchgear is a modular solution, where customer needs have been noticed. HECON product family includes two types of switchgears. HECON MCC is suitable for high current and more controlled industry applications. HECON MCC is cell feeder-based solution, where requirements for control components, large cables and high current circuit breakers are noticed (Figure 2). HECON Light is suitable for lower current applications, for example HVAC and building electricity applications. HECON Light is lighter and more cost-effective solution for these types of applications and it can also be wall mounted (As Harju Elekter. 2020).

Figure 1. Front view of HECON MCC switchgear (As Harju Elekter. 2020)

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Figure 2. Technical Data of HECON switchgears (As Harju Elekter. 2020)

1.5 Background of study

Sami Mattila, author of this master’s thesis, is working as a sales manager in Harju Elekter Oy.

The author is an electrical engineer, graduated 2012 from Satakunta University of Applied Sciences, and is currently a student of Lappeenranta-Lahti University of Technology in program of electrical engineering. It was decided that the author will start working in a development project of thermal monitoring of HECON switchgears. The results of the project will be presented in the authors master’s thesis. PhD, Marek Mägi, from As Harju Elektrotehnika was appointed supervisor for the author in this project.

1.6 Scope of study

The scope of this study is restricted in the HECON product family with MCC type solutions.

Temperature monitoring is also mainly restricted to points in the switchgear, which cannot easily be inspected with thermal imaging camera. However, with same methods, also visible points can be monitored, if necessary.

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15 1.7 Objectives of study

The objectives of the study is to use literature to determine reasons, which can cause hazardous temperatures in switchgears. This information will be used to determine points in the switchgear, where hazardous temperatures could appear. When this information is gathered, the author will start working to find a suitable solution from the temperature monitoring system manufacturers, which could be used in HECON products. After this, the author will determine, how the chosen temperature monitoring system should be installed in the HECON switchgear by using gathered information. Final stage of this study is to test this temperature monitoring system, which will be installed in HECON, and examine, is this system operating as assumed and conclusions will be made in this thesis.

The final results of this thesis include finding a temperature monitoring system, which would be reliable in the HECON installation, and developing the system architecture and design methods. Designing is based on a research information from the critical points of the switchgear. As a result of this thesis, As Harju Elekter can provide an additional option to its customers, which includes a temperature monitoring system for HECON switchgears.

Objectives of study are presented in the thesis as follows:

- Chapter 1:

o Introduction and background of study.

o Temperatures in switchgear. The chapter presents research work for basis of design and theory of hazardous temperatures in connection points.

o Wireless sensor technology. The chapter presents selection process of manufacturer and introduction of wireless temperature monitoring system.

- Chapter 2:

o Design and development of wireless sensor system. The chapter presents principles of installation design of the system, component installation methods, part list design principles and installation design for system test.

o Monitoring system development. The chapter presents data communication topology of the system in general, system software introduction and design of preliminary system schematics.

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16 - Chapter 3: Testing of system:

o Introduction of test environment, test methods, test results and conclusions.

- Chapter 4, Final conclusions:

o The chapter presents discussion and conclusions of cost of the system and benefits of the system.

o Flowcharts: The chapter presents flowcharts for design and manufacturing of the system.

1.8 Research methods

The expert interview is one of the effective methods on verifying the vision of this project.

Expert is Kalle Vuorio, who is a Chief Operating Officer of KMJ – Engineering Oy. KMJ – Engineering Oy was founded 1997 and one of the company’s service is industry thermal imaging. Kalle Vuorio has over 20 years of experience in thermal imaging and in switchgear temperature analysis in industrial applications. Interview topics are listed in the Appendix 1.

Main goal of the interview is to receive an expert opinion regarding this topic and to verify that the goals and objectives set in this project and research are reasonable and valuable. Interview is based on “free conversation” with topics listed in the Appendix 1.

When selecting temperature monitoring system, which could be used in future to improve company’s products, it must be sure that the system really works and more importantly works correctly. This will be verified with using two independent monitoring systems in addition to the chosen system. When the tests will be running, monitoring will be done with three independent monitoring systems at the same time. If the results of the temperature monitoring system that is under inspection are approximately the same as the results in two other independent systems, it can be stated that the chosen system is reliable. These systems are presented in chapter 3.2.

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17 1.9 Schedule of study

Preliminary schedule of the studies is presented in Table 1. Number explanations below.

2019

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

1

2020

1 2 3 4 5 6

2021

7

Table 1. Study schedule

Explanations of the schedule:

1. Investigation of possibilities for the thesis topic. Proposing the selected topic to the company. Discussion of the topic in Harju Elekter Oy and in As Harju Elektrotehnika.

Editing the scope and the objectives of the study to correspond with the scope of the thesis and the needs and the resources of As Harju Elekter.

2. Preliminary investigation of possible temperature monitoring system manufacturers and their products. Comparison of different system. Investigation of possibility to purchase and to use those systems. Creating table of contents for the thesis.

3. Negotiations with the manufacturer of the selected system.

4. Literature study. Preliminary design.

5. Installations and testing of the system.

6. Examination of results, conclusions and discussion. Writing process.

7. Examination of the thesis. Final corrections and finishing of the thesis.

1.10 Resources for study

The required resources for this study can be divided into three different categories. The first category is the HECON switchgear for testing. As Harju Elekter has a test HECON Light switchgear in Keila, Estonia. Switchgear can be used for system testing. The second category

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18 is the testing environment. As Harju Elekter has a HECON test environment, where the test HECON is located. This environment can be used for testing the system. In the test environment, there is a possibility to supply current to the test HECON switchgear and therefore analyse data from temperature monitoring system. The third category is the temperature monitoring system. Employer will purchase the chosen temperature monitoring system. In addition, supervisor of this thesis will advise in this study. He will provide assistance to operate in the As Harju Elekter test environment. He will also give advices and opinions concerning the complete study. Employer will also provide hotel in Estonia for the time being that is needed to carry out the testing of the system.

1.11 Temperatures in switchgear

1.11.1 Increase of resistance by loose connections, corrosion and impurity

Busbars are usually connected with bolts, which are installed through one or several holes predrilled in the busbar. A bolt is tightened with a nut to press two busbars together, thus two separated solid objects are connected together. It is important to accomplish connections correctly. Bolts, nuts and pressure plates must be suitable for connection and torque for the tightening must be correct. The target is to accomplish a connection, where the resistance is matching the resistance of solid objects as closely as possible. If for some reason the connection is not done correctly, it may have a higher resistance than the solid busbars. In the connection two surfaces are connected together. When looking very closely at the busbar surface, it can be noticed that it is not purely flat (Figure 3). The surface is slightly rough. When two surfaces are tightened together with the applicable torque value, the two surfaces will have connections with each other at nearly all areas. If the torque value is not correct, the two flat rough surfaces will not have a full area connection with each other (Yovanovich, M., Culham, J. and Teertstra, J.

2004).

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Figure 3. Rough surfaces (Yovanovich, M., Culham, J. and Teertstra, J. 2004)

When a current is flowing through the connection, the actual cross section of the connection is smaller than the solid busbar cross section. The connections may include areas, which are not tight enough to form a connection due to the properties of rough surfaces. Similar problem may evolve over a longer period of time. If the nut starts to slowly loosen up over time, the pressure between two surfaces also decreases. This could lead to a situation, where the connection of the surfaces is finally lost. (Zhou, X. and Schoepf, T. 2011). In addition, contamination and corrosion are remarkable phenomena, which can affect the connection. Impurities and corrosion can penetrate in between the two connection surfaces over a longer period of time and start to degrade the connection even though the connection is not loose. Loosening connections, contamination and corrosion are problems, which may occur in any kind of connection. Usually these will evolve slowly during time, but at some point, this phenomenon can lead to a dangerously high temperatures by increase in resistance (Alhainen, J. 2015).

For an example, let us investigate an imaginary situation, where an electric heater is supplied from a switchgear. For example, there is a 800 W/ 230 V heater supplied through MCB (miniature circuit breaker), which is connected to a terminal block (Figure 4).

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Figure 4. 100 W heater supply via MCB and terminal block

We can calculate the resistance of the heater (1) by active power and voltage in the electric circuit.

U=230 V, P=800 W, R=U² P ⁼

230 V × 230 V

800 W = 66.1 Ω (1)

Figure 5. Circuit diagram of heater supply

We can calculate the electric current in the electric circuit (2) (Figure 5).

𝑈 = 230 𝑉, 𝑅 = 66.1 Ω, 𝐼 =𝑈

𝑅 = 230 V

66.1 Ω= 3.5 A (2)

We can see that the 800 W/230 V heater has an internal resistance of 66.1 ohms. At full load, the electric current in the electric circuit is 3.5 A.

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21 Let us assume that that over time, the auxiliary block and the wire connection starts to weaken.

Reasons could be loose connection, corrosion or impurity. Let us assume that five ohm additional resistance is applied on the terminal, which could be a typical resistance for small wire cross section (Master Samurai Tech. 2015) (Figure 6).

We can now calculate the new electric current by voltage and resistance in the electric circuit (3) (Figure 7). In the Figure 7 there is a serial connection of two resistances.

𝑈 = 230 V, 𝑅 = 66.1 Ω + 5 Ω = 71.1 Ω , 𝐼 =𝑈

𝑅 = 230 V

71.1 Ω= 3.2 A (3) It can be seen that the electric current decreases in the new situation, when an increase of a resistance occurs. Let us calculate the active power for heater in this situation (4).

𝐼 = 3.2 A, 𝑅 = 66.1 Ω , 𝑃 = 𝐼 × 𝑅 = 3.2 A × 3.2 A × 66.1 Ω = 691.5 W (4)

It can be seen that the heater power decreases in the new situation, when an increase of a resistance occurs. Now we can calculate the power loss in the auxiliary terminal as a result of the increase in the resistance (5).

𝐼 = 3.2 A, 𝑅 = 5 Ω , 𝑃 = 𝐼 × 𝑅 = 3.2 A × 3.2 A × 5 Ω = 52.3 W (5)

Figure 6. Increase of resistance in heater supply Figure 7. Increase of resistance in circuit diagram

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22 We can see that 52 W power loss occurs in the terminal block because of the increase in the resistance. This power loss is basically released as a thermal energy by conducting and radiating. The temperature of an area depends on the amount of power loss and cross section of the area, where the thermal energy is released. If large amount of power is released through a very small area, the occurring heat in the area is high. Same principle concerns all kind of connections of electrical conductors (Master Samurai Tech. 2015).

1.11.2 Measurement point

The temperatures inside the switchgear varies. Temperatures inside the switchgear is a combination of the ambient temperature and also radiating and convective heat from different sources. Sources in this content are equipment or other parts of the switchgear, where electric current can flow. Power losses in the electric circuit mean that a certain amount of power is dissipated in a form of heat. Heat will be released from the circuit mainly by free convection via conductor and to a small extent by radiating from the conductor to the environment. It can be assumed, that ambient temperature is approximately the same at any point of the switchgear, when the switchgear is not operating. When electric loads and electric supply are connected to the switchgear, electric current starts to flow in the switchgear and convective heat will occur due to power losses. In this situation, there are different temperatures inside the switchgear depending on where the temperatures are being measured at. Distances from the heat sources affect all the temperature measurements. Another factor is the timing of measurements. In the switchgear, electric loads can vary in time and therefore also electric currents vary. This leads to varying power losses and therefore varying heat convection at different times. Due to varying convections and different distances from sources inside the switchgear the temperatures should be measured closely at the conductor.

1.11.3 Invisible switchgear points for wireless temperature monitoring

In this thesis the main target is to focus on invisible connection points in the switchgear.

Switchgear may consist of hundreds of different electrical connection points. It is not reasonable to try to monitor all of these points. This kind of monitoring would be almost impossible to accomplish, or it would be at least very expensive. Thermal imaging is the best way for fast

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23 monitoring of all the visible connection points of the switchgear. In contrast, it is very difficult to monitor invisible points in the switchgear with a thermal camera. One solution for this could be to install sensors to the invisible connection points.

Invisible connection points of the highest priority can be split into two categories. The first category is busbar connection points. Switchgears are split into transport units, which could be 2 – 4 meters wide parts of the switchgear. On site, the switchgear’s transport units will be

assembled. The busbar connections parts of the transport units maybe located later in non-accessible locations for thermal imaging (e.g., behind covers or cables installed in cable

canals). The second category is withdrawable ACBs and MCCBs (air circuit breakers and molded case circuit breakers), where the connection points are either behind a fixed part of device or behind touch protection plate and therefore not accessible for thermal imaging (Vuorio, 2021).

1.12 Wireless sensor technology

1.12.1 Introduction

There are many wireless temperature monitoring systems in the markets. Usually systems include sensors, antennas and the main unit. Sensors are measuring temperature and wireless communication happens between sensors and antennas. Antennas are connected to the main unit, which will process the temperature data from antennas. Usually, antennas are connected to the main unit via cables. There are some limitations for wireless systems in general. It is usual that antennas have to be installed in the same space with sensors. This is because most systems are communicating by radio frequencies, which cannot go through metal walls (Britannica, 2021). Switchgears are built from metal and all the fields and cells are surrounded by metal walls. Sensors and antennas, which are separated with a metal wall, do not work.

Sensors may also be battery powered. In that case, limitations in the battery life may be a problem. However self-powered sensors are pretty common in today’s systems. Self-powering is based on electromagnetic field occurring around cable, where the current is running (Micropelt, 2015), or technology, where an antenna sends a signal, which is then reflected back to the antenna (Benes, E., Groschi, M. and Seifert, F, 1997).

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24 After search of suitable wireless temperature monitoring system for this project, manufacturer IntelliSAW system was selected. This system is described in chapter 1.13.

1.13 Topology

Figure 8. Intellisaw temperature monitoring topology (Intellisaw. 2020. IntelliSAW Monitoring Solutions Overview 2020)

Sensors will be mounted to the points of the switchgear, where temperature shall be measured.

Sensors are transmitting data to “antennas” (or more officially air interfaces) with radio signal.

One air interface can receive data from up to three sensors. Air interfaces are connected to a reader via cables and the reader is processing the incoming data. Up to four air interfaces can be connected to one reader. Data from the reader can be transferred to a PC via USB cable and analysed by the PC software IntelliSAW Configuration Tool. With the same tool the configuration of the system can be done. The reader also has a Modbus RTU communication option, where data can be transferred forward from the system. Basically, maximum topology for a one reader system consists of a one reader, which is connected with four air interfaces, each air interface is reading data from three sensors. This is also a system that was used in this thesis. For a larger operation, IntelliSAW also provides CAM-5 touch panel HMI with monitoring. Up to nine readers can be connected to one CAM-5 monitoring unit. CAM-5 also supports Modbus TCP, DNP3 and IEC-61850 communications. In this thesis, the focus was just to test the operation of system and monitoring accuracy, so a larger than one reader system

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25 was not necessary. However, it has been taken into account that in the future it could be possible to provide also larger systems with using CAM-5. IntelliSAW also provides humidity monitoring and partial discharge monitoring for the same system. Additional humidity sensors and partial discharge air interferes can be connected to the reader. IRM-48 readers have different types of measurement supports. These options are temperature and/or humidity and/or partial discharge. In this project, IRM-48 type, which supports only temperature monitoring, was used. Scope of this project was just temperature monitoring, so the other optional measurement possibilities are not handled in this thesis. However, it is reasonable to address, that this kind of option exists (Intellisaw. 2020. IntelliSAW Monitoring Solutions Overview 2020) (Figure 8).

1.13.1 Temperature sensors

The system includes temperature sensors, which are wireless and will be mounted to the points of the switchgear, where temperature shall be measured. IntelliSAW provides two different types of sensors. IntelliSAW (IS) Sensor (Figure 11) has bolt mounting possibility for maximum of 13 mm or ANSI ½ inch, so it can be mounted for example between busbar and busbar connection bolt or between cable shoe and cable shoe connection bolt. Sensors can also be mounted by cable tie or bonding tape. Another model is Low Profile (LP) Sensor (Figure 12). Operation of this model is same as in IS model, but the physical dimensions are smaller and LP sensor does not have a bolt connection possibility, so it has to be mounted by using cable tie or bonding tape (Intellisaw. 2020. IntelliSAW Monitoring Solutions Overview 2020).

Air interference is transmitting 425 – 442 MHz radio frequency for sensor. Signal is transduced into acoustic wave by an interdigital transducer. Then the surface acoustic wave propagates along the surface of the substrate and the acoustic impulse response wave is transduced back (Moussa. H. 1997) (Figure 9). Two resonators provide a differential measurement for better signal reliability. Temperature is known from resonator signal frequency difference (Intellisaw.

2018. IntelliSAW Overview Customer Presentation 2018) (Figure 10).

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Figure 9. SAW IDT technic principle (Intellisaw. 2018. IntelliSAW Overview Customer Presentation 2018)

Figure 10. SAW IDT frequency-temperature charasteristics (Intellisaw. 2018. IntelliSAW Overview Customer Presentation 2018)

These sensors can measure temperatures in range of -25 celsius degrees to 125 celsius degrees with resolution of ±0.2 celsius degrees. Accurary of the sensors is ± 2 celsius degrees in area of 0-80 celsius degrees and ± 4 celsius degrees in full range. Base plate material is 260 Brass, Tin Plated and cover material is polycarbonate, UL94-HB. Cover Dielectric strength of the sensor is 15 kV. Bolt mounting maximum torque is 102 Nm. (Intellisaw. 2015. IntelliSAW Critical asset monitoring temperature sensors)

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27 Sensors are grouped with unique colours. Sensors are all ordered by certain bandwidth and bandwidths are identificated from band one to band twelve. Different bands are grouped by different colours. When selecting three sensors for the air interface, same colour group sensors must be selected to automatically have bands that are not adjacent. For example, orange colour group has bands 1,3 and 5 and so on. This how the possibility of reading wrong sensor by air interface is eliminated (Intellisaw. 2016. IntelliSAW Sensor Installation Manual).

1.13.2 Air interfaces

Air interface (Figure 13) must be mounted in the same space, where the sensors are, to be able to communicate with the sensors. Air interface can be mounted by magnets or bolts. Ingress protection rating of the air interface is IP40 and the operation condition is in range of -20 to +79 celsius degrees. Air interfaces are connected to a reader with double shielded coaxial cables. Air interfaces can be ordered with 3, 5, 7 or 10 meter cable. In this project, air interfaces are with 7 meter cable length (Intellisaw. 2016. IntelliSAW Sensor Installation Manual).

Figure 13. IntelliSAW Air Interface unit

Figure 11. IntelliSAW IS Sensor Figure 12. IntelliSAW LP Low Profile Sensor

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28 1.13.3 Reader

Air interfaces are connected to readers (Figure 14) four air interface inputs. Reader has voltage input connectors and it can be powered with 24-60 VDC supply voltage. Reader has also Modbus RTU connection inputs ”Data +”, ”Data –” & ”D-COM”. PC can be connected to a reader via USB cable. USB connection enables configuration of the system and analyzation of temperatures. Reader has a small led, which indicates operation of the reader by different colours and blinking. Reader can be mounted to 35 mm din rail to horizontal or vertical position.

AC/DC power supply, which is powering the readers, must be protected from the AC side with two pole MCB. Earth wire must be connected to the reader’s earth connection. Reader can process data of 12 sensors via 4 air interfaces in the frequency range of 425 to 442 kHz. IP class of the reader is IP40 and operating conditions between -40 to +70 celsius degrees. Elevation of the reader should be under 5000 meters (Intellisaw. 2016. IntelliSAW IRM-48 Reader Installation Manual).

Figure 14. IntelliSAW IRM-48 Reader unit

1.13.4 Software

IntelliSAW has a free system configuration tool, which can be installed on PC. In configuration, the first operation is to create a sensor register for sensors. Each definition consists of a sensor frequency band (1-12), a calibration code, and the air interface, which is used to interrogate the sensor. The temperature commissioning references 12 locations, each with the ability to use some or all the 4 air interfaces, providing for redundant measurements. Each location has four sensor definitions, which are identical except for the air interface assigned and whether the measurement is enabled. Band and calibration codes are printed to each sensor. Modbus register

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29 for sensors can be created in the configurator. Physical location of sensor can be added for Modbus register to clarify certain sensor register number.

After installation, calibration of the system must be made to receive correct values. In the calibration the ambient temperature is set to the configurator. Configurator has temperature sensor display, which presents temperature and sensor signal strength (Figure 15). Modbus temp readings display (Figure 16) is available in the configurator. It presents a graph of temperature data based on the Modbus register. There is also possibility to download recorded data into Excel file (Intellisaw. 2016. IntelliSAW Configuration Tool User Manual).

Figure 15. Temp Sensor Display view

Figure 16. Modbus Temp Readings Display view

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30 1.13.5 Standards related with topic

IEC 61439 is the standard concerning manufacturing of switchgears. HECON manufacturing is done in conformity with this standard. The chosen temperature sensors and air interfaces are type tested for low and medium voltage applications according to IEC 62271-100 “MV Switchgear, Voltage resistance: 95 kV/1m, 185 kV pulse” (Intellisaw. 2017. IntelliSAW Critical asset monitoring air interfaces). The sensors are also type tested according to IEC 62271-200 “MV Switchgear, Short circuit withstand: 63 kA/3s, 171 kA peak” (Intellisaw. 2016.

IntelliSAW Sensor Installation Manual). Reader unit product is certificated according to IEC6100-6-5 “Level 4 substation EMC/EMI per IEC61000-4-x” (Intellisaw. 2016. IntelliSAW IRM-48 Reader Installation Manual).

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31

2 DESIGN AND DEVELOPMENT OF WIRELESS SENSOR SYSTEM

2.1 Introduction

In this chapter the general approach of the designing of Intellisaw system to the HECON switchgear is presented. The layout of the switchgear can vary a lot in different projects.

Switchgears can have different amounts of outgoing protection devices. Typically for very low power loads (< 32 A), MCBs are used. For higher loads (63 - 800 A), the typical solutions are fused switch disconnectors as protection devices. For even higher loads or for specific protection settings, MCCBs and ACBs protection devices are used. Fuses are nonadjustable solutions, but protection relays offer a variable range of settings to adjust protection (e.g., tripping to lower short circuit currents or for selectivity reasons). Typically, MCCB’s are used in the range of 160 A to 1250 A and ACB’s are typically selected for higher rated currents even up to 5000 A.

In the case of busbars, it can be stated that the connections are every time invisible, when typical HECON structure is used. For ACBs and MCCBs the connection method can vary according to the rated current. For smaller MCCBs, it is typical to use a cable supply and cable shoe connection. These cable shoes are usually visible in the cell and can be analysed with a thermal imaging camera. For higher nominal currents busbars are typically used as supplying conductors. Compact breakers can have horizontal or vertical connections, which indicates, whether the conductor is connected to the breaker “from behind” or ”from top”. This information does not give exact information whether the conductors are visible or not as the switchgear design might include other installed devices or covers in the same section.

The number of invisible connections may be extremely high. Suppling conductors between the main busbar and the protective device have two connection points, one at the end of the main busbar and the other at the end of the protection device. Even when the protection device would have visible connections, the other end of the conductor is still invisible in the main busbar compartment. Thus, the main busbar side has at least three invisible connection points (in a three-phase system for every phase) and more for every other bigger fuse switch disconnector, MCCB or ACB.

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32 Reasonable way to design wireless temperature monitoring system is required in the designing.

For example, in a three-phase system, where there are 40 three-phase protection devices there would be 120 invisible connection points in the busbar compartment. This would require 120 sensors, 40 air interfacess and 10 readers just in the busbar compartment and increase the cost of the monitoring system. A reasonable amount of measurement points for the busbar compartment including transport breaks would be three for every transport break (one per phase). Also, incoming and outgoing ACBs and MCCBs, whose connections are covered, should be monitored. ACBs and MCCBs have incoming and outgoing connections, so six sensors per a breaker is needed (three installed in the incoming and three installed to the outgoing terminals) (Figure 17).

Figure 17. Example of monitoring points in a HECON switchgear

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33 2.2 Example layout of HECON switchgear

A typical HECON switchgear would be for example approximately six meters wide, with rated current of 3200 A and rated operational voltage 400 V. In this example (Figure 18) an ACB with a rated current of 3200 A is the main breaker of the switchgear. It is very common, that an auxiliary space for all the auxiliary equipment is located next to the main breaker section. This example also includes variable speed drives (VSD) and fused switch disconnectors as outgoings. In addition, the example switchgear includes separate spaces for MCB and RCD and two ACB with a rated current of 1250 A. This example consists of two transportation units.

Figure 18. Example layout of HECON switchgear (Appendix 2)

2.3 Installation of sensors to HECON switchgears

When installing sensors and air interfaces, the following instructions should be obeyed to achieve the best possible connection between the sensors and air interfaces (Figures 19 - 21).

These figures illustrate an air interface (left side/top of the figures) and a sensor (right side/bottom of figure). Dashed line illustrates communication signal direction. Dashed lines should be as codirectional and towards each other as possible.

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34

Figure 19. Most optimal connection (Intellisaw. 2016. IntelliSAW Sensor Installation Manual)

Figure 20. Average connection (Intellisaw. 2016. IntelliSAW Sensor Installation Manual)

Figure 21. Least optimal connection (Intellisaw. 2016. IntelliSAW Sensor Installation Manual)

The air interfaces are easy to install because of their permanent magnet connection. The air interfaces can just be attached to any ferromagnetic metal surface without any additional clamps. It is also recommended to leave >100 mm distance between a metal surface and the air interfaces. Figure 22 illustrates air interface unit installed to metal surface near metal wall.

Distance between unit and wall should be over 100 mm.

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35

Figure 22. Instruction distance between air interface and metal surface (Intellisaw. 2016. IntelliSAW Sensor Installation Manual)

It is possible to offer different temperature monitoring packages (sets) to different projects.

These packages could be separated as a ”busbar package” and a ”circuit breaker package”. The busbar package contains one air interface and three sensors per one transportation break. The breaker package contains two air interfaces and six sensors per one circuit breaker.

According to this, the amount of IntelliSAW components for the example HECON switchgear in the Figure 18 could be calculated. The following packages should be selected:

- 3 circuit breaker packages (2 air interfaces and 6 sensors).

- 1 busbar package (1 air interface and 3 sensors).

Total of 7 air interfaces and 21 sensors are required for the given example. Also, one additional reader is needed because of the number of the air interfaces is more than four, but less than nine.

2.4 Schemas of the system for example HECON switchgear

Figure 23 illustrates the installation locations of sensors as described in chapter 2.3. The layout has been simplified compared to the original. Air interfaces are connected to the readers via cables. Busbars are presented with three-phase approach. Auxiliary cabinet is included as switchgears are commonly equipped with multiple auxiliary devices. IntelliSAW readers and needed auxiliary components can be easily fitted in the auxiliary cabinet. Wiring diagram and necessary auxiliary components for reader are illustrated in Figure 24.

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36

Figure 23. Installation locations of IntelliSAW components

Figure 24. Wiring diagram of the reader (Intellisaw. 2016. IntelliSAW IRM-48 Reader Installation Manual)

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37 2.5 Layout of the test system

In this thesis the IntelliSAW temperature monitoring system was tested in practice. Figure 25 shows a simplified layout of the HECON test switchgear that was used for the testing of the temperature monitoring system. Figure 25 indicates the location of the sensors in the test switchgear. The main switch is indicated in the figure on the top leftside of the switchgear and the supply cables will be connected from above to the main switch. The main switch is connected with the horizontal main busbar system. The outgoing MCCB is connected with the horizontal main busbar system with wires and the outgoing cables are connected from above.

Figure 25. Test HECON component locations

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38 2.6 Part list of the test system

For the testing of the temperature monitoring system in the thesis the following IntelliSAW components were determined for the HECON test switchgear (Figure 25) and purchased.

The following parts were selected.

Sensors:

- 6 x LP-XX (Band 01- 06) Intellisaw Low Profile Temp Sensor - 6 x IS-XX (Band 07- 12) Intellisaw Standard Temp Sensor

Air interfaces:

- 4 x IA-MM-TMP-7 Intellisaw Air Interface Base Unit, Temp Only, Mag Mount, 7 m cable

Reader:

- 1 x IRM-48-T00 Intellisaw Remote Monitoring Unit, Temp Only

Auxiliary components in the tests were:

- 1 x Power Supply 230 VAC/24 VDC: Omron S8VK - S03024 - 1 x 2-pole C-curve 4 A MCB: Siemens 5SY4204-7

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39 2.7 Monitoring system development

2.7.1 Introduction

IntelliSAW has its own hierarchy depending on how large the system is in question. The minimum number of required devices to view the temperature data is one reader. When air interfaces are added to the system the number of readers will also increase. Transferring data outside the IntelliSAW system depends on the external customer system and should be determined individually in each case. If a Modbus RTU is a suitable protocol for the customer, it can be easily transferred forward. In other cases, protocol change has to be done with a suitable gateway. The gateway can be installed into the switchgear or it can be located in another place depending on the customer architecture. In addition, an additional RTU unit could be installed into switchgear, from where the Modbus data can be sent and the RTU unit would be a part of the factory control system. Figure 26 presents an example of RTU principle with Siemens Simatic RTU, where different kinds of measurement data can be centralized and forwarded to the Simatic automation system. This is just an example of one manufacturer-based automation system, but some other manufacturer’s system could also be used.

Figure 26. Example principle of Siemens Simatic RTU (Siemens. 2021)

2.7.2 Topology of monitoring systems

Reader IRM-48 can send data of temperature values forward in Modbus RTU protocol. This data can be sent to control systems directly in the same protocol or the protocol can be transformed from the Modbus RTU to an another one with gateways (Figure 27). Gateway can

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40 be installed into the switchgear auxiliary cabinet or the transformation can be executed in a different location if Modbus RTU RS-485 data is transferred via field cable.

Figure 27. Example Modbus RTU gateway connection to Modbus TCP Scada. (Lin, J. 2016)

When multiple readers are used, the units can be connected in parallel as presented in the Figure 28. Half-duplex RS485 shielded 3- wire twisted-pair cable is recommended to be used for data connections. When long stretches of cables are used, 120 ohm resistors must be used at the end of the termination to ensure correct resistance. If the bus length is under 20 meters, termination resistors may be omitted (Intellisaw. 2016. IntelliSAW IRM-48 Reader Installation Manual).

Figure 28. Diagram with multiple readers (Intellisaw. 2016. IntelliSAW IRM-48 Reader Installation Manual)

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41 CAM-5 unit can be very helpful part of the system, if the number of readers is high. In such cases, multiple readers can be connected to a CAM-5, which could be connected further with Scada. CAM-5 units can also be connected in parallel. The topology is presented in Figure 29.

In conclusion, the CAM-5 units are additional components for the IntelliSAW system in cases, e.g., where the local door monitoring is required or in cases where the system is large and multiple readers are in use.

Figure 29. IntelliSAW CAM-5 system architecture (Intellisaw. 2020. IntelliSAW Monitoring Solutions Overview 2020)

2.7.3 Software setups with Modbus IP-addresses to view data

IntelliSAW Configuration Tool is a software, which is used to configure the system and to monitor and log temperature data. At configuration, the air interface ports and sensors are determined. IntelliSAW recommends not to install adjacent sensors under the same air interface for sensor identification. It is recommended to have one number skip in sensors under the air interface. In example, when using sensors 07, 08 and 09 for the air interface in the port 1 and sensors 10, 11 and 12 for the air interface in the port 2 is incorrect. Instead, sensors 07, 09 and 11 for the air interface in the port 1 and sensors 08, 10 and 12 for the air interface in the port 2 is correct.

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42 In the sensor register edit, air interfaces for the four different ports must be selected. The correct sensor identification codes must be determined for each port. Identification code is the number of a band and a specific letter for each sensor. Identification codes are presented on the sensors.

Location of the sensors can also be also determined in the configuration. This helps to keep in mind, which sensor is in which location. Temperature data is read from the Modbus register.

Each sensor data in the Modbus register number can be seen from the temp sensor display. This info is also used, when data is transferred to external factory control system. Data is read from the register and it must be known, which sensor data is under which Modbus register number.

Figure 30 presents a temp sensor display, where the above-mentioned data are presented. In the first time all the sensors can be calibrated with the ambient temperature. Bars under each temperature display are presenting signals between the air interface and the sensor. Signal can be green, yellow or red, which are indicating ”good”, ”average” or ”bad” connection.

Figure 30. Temp Sensor Display

Modbus temp readings window presents a graph of temperatures in real time (Figure 31). This view presents temperatures similar to the temp sensor display, but it has a 30-minute horizontal time axis, so the last 30-minute data can be seen from the graph.

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43

Figure 31. Modbus Temp Readings

Both windows have ”Log data” button. With this function data can be recorded to a Excel file.

Temperatures of each sensor is written to excel in one row in every second with the date and the time stamp. Data log can be started and ended manually (Intellisaw. 2016. IntelliSAW Configuration Tool User Manual).

2.7.4 Conclusions and preliminary solutions

In every project the structure of the switchgear and data monitoring demands can vary.

However, some preliminary electrical schematics for typical solutions can be created in advance. It has been decided in the thesis that preliminary electrical schematics shall be created for four typical solutions. Each schematic shall consist of main components and wirings. These schematics can be easily modified to meet certain project demands. Also, different solutions can be combined with each other.

The four typical solutions are:

- Example 1: Single switchgear with one reader. Data monitoring on local laptop via USB (Appendix 3).

- Example 2: Single switchgear with one reader. Data monitoring for the customer through gateway (Appendix 4).

- Example 3: Example 3: Single switchgear with multiple readers. Data transmitted to the local Simatic CPU. Possibility to view data locally by HMI. Possibility to forward data to customer via Profinet (Appendix 5).

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44 - Example 4: CAM-5 solution for multiple switchgears (Appendix 6).

For each solution wiring schematics, communication and device layouts are presented. Also, one part list is included, which includes all the required devices for the monitoring system (Appendix 7).

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45

3 TESTING OF SYSTEM

3.1 Test environment

Tests were performed in the test area of Harju Elekter Elektrotehnika, Keila Estonia. HECON LIGHT switchgear (Figure 33 – Figure 36) was used for the testing. The technical specifications of the switchgear are presented in Table 2.

Type HECON

Serial number HECON0029/307109

Rated operational voltage Ue 230/400 V Rated operational voltage Ui 1000 V Rated impulse maximum voltage Uimp 8 kV Rated current of the assembly InA 630 A Rated conditional short-circuit current Icc 20 kA Rated peak maximum current Ipk 41 kA Rated 1 second short-time maximum current Icw 20 kA Rated frequency fn 50 Hz

Degree of protection enclosure IP44

Earthing system TN-S

Main busbars (L1, L2, L3) 2 × 30 × 10 Al

Main busbars (PE) 1 × 30 × 10 Al

Enclosure dimensions H × W × D [mm] 2100 + 100 × 750 × 265

Table 2. Technical specifications of HECON LIGHT test switchgear (Appendixt 4 & 5)

The main devices in the switchgear concerning the tests were the main switch, busbars and the outgoing MCCB. There were other devices in the switchgear, but those did not participate in the tests and are therefore not presented in this thesis.

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46

Figure 34. View of HECON test switchgear with doors open

Figure 33. View of HECON test switchgear with doors closed

Figure 36. MCCB 250 A in the HECON test switchgear, Siemens 3VA1225-4EF32

Figure 35. Main switch in the HECON test switchgear, Socomec Sirco 630 A

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47 3.2 Testing method

The tests were performed with two different scenarios (test 1 and test 2). In both scenarios, the temperatures of the main switch’s incoming and outcoming connections were measured. IS type sensors were used for measuring the connection points of the main switch. The sensors were attached on the supply cable insulation as close as possible to the connection point. IS type sensors were installed under the bolts of the outgoing busbars of the main switch. The differences between the tests were that in the test 1 the main switch (MS) and the busbars were tested with the rated current (630 A). In the test 2 additional sensors were attached to the load side phase cables of the outgoing MCCB and sensors from the main busbars were reinstalled to the supply cables of the MCCB that were connected with the busbars. Then MCCB was loaded with the rated current of the MCCB (250 A) with load resistors.

In both tests, temperatures were analysed with three different monitoring systems. The IntelliSAW system, which was the system under testing and verification, was the main system.

The second system was Harju Elekter’s self-assembled temperature monitoring system with wired sensors. The wired sensors were installed in the same locations, where the wireless IntelliSAW sensors were installed. The third system was thermal imaging. Thermal images were taken at the end of each test from the same locations, where wired and wireless sensors were installed. The results from all the three monitoring systems were compared after the tests.

The wired sensor system was built from the following devices:

1. Thermocouples Z2-K-5M, Farnell 2. Amplifiers AD8495, Analog devices

3. PicoLog 1012 Data Logger and PP604 Terminal Board

Thermal camera that was used in the tests was Fluke Ti400.

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48 Prior to the testing the expected busbar temperatures were evaluated. The busbars in the HECON test switchgear were sized according to the rated current of the switchgear, doubled 30 x 10 aluminium (for currents up to 780 A in free air, according to reference ABB. 2000).

The temperature rise of the busbars was designed 30 K. The ambient temperature according to the standard IEC 61439-1 must be considered 35 celsius degrees. The expected end busbar temperature would be 65 celsius degrees at the ambient temperature of 35 celsius degrees. The load current in the test 1 was 630 A, which is lower than 780 A, and the ambient temperature in the tests was appr. 22 not 35 celsius degrees, so the first expectations were that the busbar temperatures could be lower than 65 celsius degrees. However, in the tests all the air ventilations were blocked to meet the general IP44 protection degree for the switchgear. When natural air ventilation is not considered in the switchgear, the air temperature inside the switchgear should be higher, thus the busbars heat up more and the busbar temperatures would be higher than in free air. (ABB. 2000)

When both tests were performed, similar results from each temperature monitoring system were expected. Should the results be similar, it could be stated that the installation and configuration of the IntelliSAW system was successful and the system is working correctly and the data received is reliable. Should these three monitoring systems give all different data, further testing and analysis must be done, which of these three monitoring methods is accurate.

In both tests (test 1 and test 2), sensors were installed to monitor the main switch’s incoming and outgoing connections (Figure 37).

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49

Figure 37. Sensors installed on the connection points of the main switch

The HECON test switchgear was powered by Harju Elekter’s own supply cabinet. The supply cabinet is designed to carry out different temperature rise tests. The supply cabinet consists of a three-phase 17 kVA main transformer, which primary side can be supplied from the grid (400 VAC). The voltage of the secondary side of the voltage transformer is very low, only 3 x 1,5-3,5 VAC, but this enables high output current up to 4000 A (Figure 38).

Figure 38. Main transformer of the supply cabinet

The supply cabinet contains an adjustable autotransformer per each phase, where the primary voltage of the main transformer can be adjusted. With the autotransformers it is possible to adjust the output current of the supply cabinet. In the testing area, it is possible to test different switchgears either by short-circuiting the test switchgear’s main busbars with a copper busbar to load the switchgear without any loads (with the autotransformers it is possible to adjust the

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50

“short-circuit current” to the rated current of the switchgear) or by loading outgoing circuits with loading resistors. The HECON test switchgear main busbars were short circuited (Figure 43) in the test 1 to load the switchgear with rated current of 630 A. Autotransformers can be seen in the Figure 39 just above the cable connection. The meters above the autotransformers display values of voltages and currents in the grid side.

Figure. 39 Supply cabinet

3.3 Software setup

Prior testing the auxiliary components of both monitoring systems were placed outside of the test switchgear. Author and the electrical engineer from As Harju Elekter Elektrotehnika supporting these tests were both analysing data throughout the testing. Figure 40 presents the test environment, where were two laptops, one for the wired system and one for the wireless Intellisaw system. Author was operating with the IntelliSAW system data.

.

Figure 40. Test environment, data analysing

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51 IntelliSAW system configuration was done successfully according to the manufacturer’s manual (Intellisaw 2016. IntelliSAW IntelliSAW Configuration Tool User Manual). Each sensor was found by the system and temperatures were corresponding to the ambient temperatures. Sensors were named by the locations, where those were installed (Figure 41).

Figure 41. Sensor data in temp sensor display before tests.

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52 3.4 Test 1

In the test 1 the HECON test switchgear main busbars were short circuited (Figure 43) to load the switchgear with the rated current of 630 A. Figure 42 presents the principle diagram of the test 1. The same figure can be found from the appendices, Appendix 8.

Figure 42 Principle diagram of test 1

The HECON test switchgear had been designed in a way that it was easy and safe to short circuit the busbars. Figure 43 presents the short circuit bar that was used to connect the main busbars together.

Figure 43. Short circuit busbar

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53 Figure 44 presents the installation of busbar sensors.

Figure 44. Test 1 register 424-426 sensors

In test 1 sensors were installed as shown in figures 37 and 44. In this test the outgoing MCCB feeder was not analysed and excessive sensors of registers 427 – 429 were used to measure the cable connections of the supply cabinet. One sensor was placed to measure the ambient temperature and the two sensors were installed to measure the phases of L1 and L2 of the cable connections of the supply cabinet (Figure 45).

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54 3.5 Test 2

In test 2 the outgoing MCCB feeder was loaded with rated current and the temperatures of the cable connections of the MCCB were measured. Figure 46 presents the principle diagram of test 2. The same figure can be found from the appendices, Appendix 9.

Figure 46. Principle diagram of test 2

In this test, the MCCB was loaded with load resistors and the short circuit busbar was not used.

The sensors presented in Figure 47 were installed to the outgoing cable connections of the outgoing MCCB.

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55 Sensors that were installed to the busbars in test 1 were re-installed to the cable connections of the cables between busbars and outgoing MCCB (Figure 48).

In test 2 loading resistors were used (Figure 49). In the trolley there were four three-phase step- up transformers (that the currents in the loading resistors would be smaller compared with the currents in the switchgear) and three adjustable load resistors per each phase of the step-up transformer. In test 2, only one step-up transformer was needed to load the MCCB.

Figure 49. Loading resistors in test 2

Development of temperature monitoring for HECON switchgears

ABSTRACT

TIIVISTELMÄ

ACKNOWLEDGEMENTS

CONTENTS

NOMENCLATURE

1 INTRODUCTION

2 DESIGN AND DEVELOPMENT OF WIRELESS SENSOR SYSTEM

3 TESTING OF SYSTEM