1.13 Topology
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
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
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
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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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.
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
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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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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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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Figure 23. Installation locations of IntelliSAW components
Figure 24. Wiring diagram of the reader (Intellisaw. 2016. IntelliSAW IRM-48 Reader Installation Manual)
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
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
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
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)
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.
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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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).
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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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
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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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
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.
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.