References for electric public transport

1. Project for conversion of NRV trams to 750 V supply voltage – 2020 and implementation – 2021. The voltages, currents and temperatures of the tram drive components were modeled on a computer at 25% increased supply voltage. The operation of the auxiliary power converters and the battery charger was tested up to 1100 V DC. Tram driving tests at increased supply voltage – will continue in 2021.

2. Update of the automated tester software for tram NRV electronics assemblies and 3-day training of HCT’s new electronics specialists: MLNRV control system, control electronics, tester and its use – continues in 2021.

3. Production of upgraded RCDs for trams MLNRV I, MLNRV II of HCT – 2021. The RCD measures the leakage current of the insulation of the tram’s DC power circuits. If the limit value is exceeded, the main switch of the tram is switched off.

4. Production of modernized control cards B6ML for HKL trams MLNRV I, MLNRV II – 2019, 2021. The control card B6ML forms the control signals of the tram traction drive during acceleration and braking.

5. Study of HKL Artic battery charger-inverters on the possibility of alternative units – 2019. The customer was interested in whether it is possible to use alternative converter units.

6. Production of MLNRV II RCD circuits (snubbers) for trams  – 2018, 2016. The RCD circuit of the traction converter limits the overvoltages of the power semiconductors during the electric braking process.

7. Examination of wheel axle magnetization and faults of forced stop devices of  HKL metro trains type M200 – 2017. It had to be checked, whether the magnetization of the wheel axles could have caused false applications of the forced stop device.

8. Preparation of an expert opinion on the market price for the repair of HKL metro trains M100 PWM power modules – 2017. The client needed an expert assessment.

9. Production of modernized control cards B10 for trams MLNRV I, MLNRV II – 2017. B10 controls the magnetic flux strength of traction motors during acceleration and braking depending on the tram speed and traction power reference.

10. Design and production of modernized control cards B14, C2, C6 / C10, A38 / B2, B22, A2, A26, A14, A18, A30, A34 and B6ML for trams MLNRV I, MLNRV II – 2016. During the modernization, the control electronics were transferred to a modern element base. More complex analog circuits were replaced by microprocessor circuits.

11. Design and installation of an energy meter for the CAF Urbos tram of Tallinna Linnatranspordi AS – 2016. The customer requested the addition of an energy meter in order to keep accurate records of the energy consumption of a specific type of tram in relation to carbon dioxide quotas.

12. Design and production of modernized control cards A22, A18, A30, B18, B26, A10 for trams MLNRV I, MLNRV II – 2015. During the modernization, the control electronics were transferred to a modern elementary base. More complex analog circuits were replaced by microprocessor circuits.

13. Leakage current problem consultation on HKL MLNRV trams no. 104 and 105 and 77 and 79 – 2015. It was necessary to find out the reason why the fault current protection was applied between these trams, although everything seemed to be in order. The increased leakage current was partly caused by broken wheel ground connections.

14. Update of the test program of the card tester of control cards A18 and A22 – 2015. The test programs were updated according to the customer’s wishes.

15. Design and production of modernized control cards B18, A10, B26 for trams MLNRV I and MLNRV II – 2014. During the modernization, the control electronics were transferred to a modern elementary base. More complex analog circuits were replaced by microprocessor circuits.

16. Design and manufacture of electronic assembly automatic test equipment (ATE) for testing the electronics of HKL NRV trams in 2014. Manual testing of complex electronic control cards requires a qualified electronic engineer and the work can be time consuming and expensive. ATE can test 24 different electronic assemblies. Testing is performed either automatically, manually, or by step-by-step troubleshooting. ATE enables very fast, accurate and complete tuning and testing of complex electronic equipment without the need for a highly qualified employee. Test reports are automatically saved to a USB memory stick or sent to the server.

17. Design and production of modernized control cards C14, C24, C30 / C34, C38, B30ML, B34M / B38M, B6M for trams MLNRV I and MLNRV II – 2013. During the modernization, the control electronics were transferred to a modern elementary base. More complex analog circuits were replaced by microprocessor circuits.

18. Production of HKL MLNRV I safety thermostats PTH200, PTH100C, door sill overtemperature protection 40°C and heating cables – 2013. Safety tram thermostats with a special tram design, which must prevent overheating of equipment in the event of a thermostat failure, are located near heaters and in the hot air duct. The floor and door sill of the fiber-based composite material of the low-bottom intermediate part of the tram are electrically heated with heating cables. Overtemperature protection prevents the floor from overheating in the event of a thermostat fault.

19. Production of HKL MLNRV I rail brake diode blocks SLDB40B1 and RCD assemblies (snubbers) – 2012, 2013. The added low-bottom intermediate part has 2 rail brakes to achieve the required braking distance. In an NRV, the series connected rail brakes are normally supplied with 600 V. When the line voltage is lost, the rail brakes are switched to the 24 V supply in parallel. The changeover of the rail brake is performed with contactors and diode blocks with a special solution. The RCD circuit of the drive inverter limits the overvoltages of the power semiconductors during the electric braking process.

20. Development and production of new solutions for various electrical equipment for HKL NRV trams – 24 different control cards, including microprocessor – controlled ABS system, power electronics assemblies and equipment, heating controllers, etc.

21. Production of tram MLNRV I temperature sensors ETS50 / 150, CTS50 / 150, ITS50 / 150, PTH100C, underfloor heating overtemperature protection – 2012. A controller and a series of temperature sensors are used to control the air conditioners in the low-floor intermediate part of the tram. Overtemperature protection prevents the floor from overheating in the event of a thermostat fault.

22. Production of tram MLNRV I temperature controllers HC24, diode blocks SLDB40B1 and heating cables – 2012, 2009 and 2008. A specially designed controller and a series of temperature sensors are used to control the air conditioners of the low-floor intermediate part connected to the tram. Heating cables are used for underfloor heating. Diode blocks are used in 600/24 V supply circuits for rail brakes.

23. Advising on the addition of low-floor intermediate sections for HKL trams NRV I and electrical project – 2012. HKL selected ET-Ex Machina (Energiatehnika OÜ), which had previous experience in NRV II and KT4SU intermediate projects, to carry out and advise on the electrical project for adding NRV I low-floor intermediate sections. The electrical equipment of the NRV Type I tram is largely similar to the NRV II, but the layout and cabling are significantly different. As the NRV I is an older type, some of the devices are also of an older type and the extent of the required upgrade was higher. The drawings and diagrams of the electrical part no longer corresponded to reality and had to be completely updated. Detailed change instructions were prepared to facilitate the conversion and to implement the same.

24. Design and production of modernized control cards B6M, B30ML, B34M / B38M for trams MLNRV I, MLNRV II – 2012. During the modernization, the control electronics were transferred to a modern elementary base. More complex analog circuits were replaced by microprocessor circuits. The B6ML control card generates the tram traction control signals during acceleration and braking. The B30ML controls the traction and braking force of tram traction motors based on speed sensor signals from cards B34M / B38M. During acceleration and braking, the slip of the drive wheels is controlled to stay within a predetermined range, preventing locking (ABS). New features include 1) automatic wheel wear compensation based on first idle speeds; 2) increased slip in winter conditions; 3) possibility to save the logbook on the memory card.

25. Electrical design of Stadin Radikat OY historical tram V 50 (1909 ASEA) electrical system restoration, electrical installation, traction engine repair, tram testing and handover in 2012. Connection to open trailer No. 233 (2013) and advice on transition to 750 V supply voltage were also planned. Stadin Radikat AB collects and restores historical trams and transports tourists with them in Helsinki. Prior to the restoration, practically all electrical equipment was missing from the tram, all that was left was the main switch, the traction controller in very poor condition and some cables over 100 years old that could not be used. In essence, we designed a new electrical installation, which was made externally as similar as possible to the original. The Strömberg traction motors and control controller were taken from donor tram no. 135 (1948). The traction engines were repaired and the tram was equipped with additional sensors to control the brake lights, rail brakes and the trailer wagon brakes. As the tram was to be used to transport tourists with an open trailer, it had to pass the same acceptance tests as for regular trams. The tram did not originally have rail brakes, but these had to be added to ensure the required braking distance and safety. This required a rebuild of the undercarriage, 24 V power and batteries that were not in the original. For the forthcoming changeover to 750 V, the battery charger must be replaced, the capacities of the accelerator and braking resistors and the voltage resistance of the components must be checked.

26. Consultations on the installation and adjustment of the MLNRV II refrigeration unit – 2011. NRV type II trams did not initially have an air conditioner and the need to add a refrigeration unit to the low-bottom intermediate sections became clear later and required significant changes. In order to ensure reliability, it proved necessary to ensure uninterrupted supply of refrigeration compressors when passing through line separators. Special ultra-capacitor energy storages were used for this purpose. The air conditioner also had to be paired with a low-floor wagon heating controller and redesigned with this software.

27. Production of HKL MLNRV underfloor heating cables and diode blocks SLDB40B1 – 2011. The low-bottom intermediate part attached to the tram was equipped with underfloor heating using heating cables. Due to the special supply voltage and small length, heating cables with a special solution had to be made. Diode blocks are used in the 600/24 V supply circuits of the added middle section rail brakes.

28. Update of MLNRV I and MLNRV II documentation, taking into account the added low-floor intermediate part – 2011. Initially, only the low floor intermediate part was designed. Due to the large number of changes that had to be made to the original wagon systems to add the intermediate part, which had not been accurately documented before, the documentation for the entire electrical and automation equipment had to be updated for both types of trams.

29. Preliminary study on the addition of the NRV I intermediate section to HKL trams – 2011. First, low-floor intermediate sections were added to 42 NRV type II trams. As this project was a good success and there was no certainty about the fate of the Variotrams, it was decided to equip 10 NRV I series trams with a low-floor intermediate section. As they are significantly older and technically different, the feasibility of a solution for adding an intermediate part needed a separate study.

30. Modernization of HKL tram GT6 and GT8 control equipment and production of servo drives – 2011, 2009 and 2008. As there were difficulties in operating Variotram type trams, in 2005 HKL bought. 11 GT6 and GT8 trams (Düvag) from Mannheim, Germany, for the World Championships in Athletics. 10 of them were equipped with HKL equipment and new dashboards produced by us, one GT8 was left in its original form. Helsinki’s tram drivers were accustomed to the light control levers of modern trams, so there was a grumble about using GT tram’s manual (crank) control controllers, which tired the tram driver’s hand. To solve the problem, joystick-operated servo drives were proposed and ordered from us. As the control of the controller was guaranteed to work even in the event of a power failure, an ultra-capacitor energy storage device was added to the servo drive.

31. Production of temperature sensors ETS50 / 150, ITS50 / 150 and temperature controllers HC24 for HCT MLNRV trams – 2011. Controllers HC24 were used to control the air conditioning of the low-floor intermediate part of the tram with indoor and outdoor temperature sensors.

32. Design and production of modernized control cards B30ML, B34M / B38M for trams MLNRV I, MLNRV II – 2011 and 2010. B30ML controls the traction and braking force of tram traction motors according to the speed sensor signals coming from cards B34M / B38M. During acceleration and braking, the slip of the drive wheels is controlled to stay within a predetermined range, preventing locking (ABS). New features include 1) automatic wheel wear compensation based on first idle speeds; 2) increased slip in winter conditions; 3) possibility to save the logbook on the memory card.

33. Electrical project for the modernization of the control system of the HCT historic tram 157, carried out for connection to Stadin Radikat AB’s restored open trailer 233 and tests – 2009 and 2011. Tram 157 did not have a 24 V system and a battery that had to be added. The interior lighting was changed to 24 V for safety. Equipment for controlling the trailer wagon brake was added. Trailer 233 was restored in Estonia. It originally had a 600 V active electromagnetic brake that could not be restored. The trailer was fitted with 2 NRV electro-hydraulic spring brakes, which are applied with half force when the controller of the tram 157 is turned more than 50% on the brake side or the compressed air brake pressure exceeds 1.8 bar. The rear wagon brakes apply with full force when the controller is fully turned on the brake side or the pressure in the pneumatic brake system exceeds 4 bar. Since 2013, the restored historic tram V50 (ASEA 1909) has been used to transport the open rear wagon 233.

34. Investigation of the wear problems of M200 gears of Helsinki metro trains 2010. Modeling and measurements of common signal disturbances on traction motors. The last traction motor and gearbox of the M200 metro train wagon all too often had failures in the bearing and gear surfaces, which may have been caused by high-frequency leakage currents of the traction converter and motor through the wheelsets. The measurements were used to find out the reasons for the increased leakage current and the current paths, and to make changes to the earthing system on the test wagon and to limit the leakage current.

35. Update of HKL MLNRV II maintenance and repair instructions – 2010. Low-floor intermediate sections were added to NRV II trams, which contain a number of equipment that needs maintenance and repair over time. A number of new devices were also added to the original wagons and the existing ones were modified. In this context, the tram maintenance and repair instructions needed to be updated and significantly improved.

36. Production of HKL MLNRV II rail brake diode blocks SLDB40B1 and RCD assemblies (snubbers) – 2010. Diode blocks are used in the 600/24 V supply circuits of the attached low-floor intermediate section rail brakes. The RCD circuit of the drive inverter limits the overvoltages of the power semiconductors during the electric braking process. In almost half of the trams, the RCDs had been removed, but at increased power they were unavoidable, and new assemblies of RCDs had to be produced.

37. Design and installation of energy meters on HCT trams NRV I, MLNRV II and Variotram – 2010. In order to find out the energy consumption of different tram types, as well as the effect of different driving style, it was necessary to install energy meters on trams. The choice and installation of the meter was complicated by the need to measure the relatively high DC voltage and current of the tram, as well as finding suitable places for sensors, meters and additional equipment, cables, etc., ensuring the required safety.

38. Consultation on the preparation of the specification for the electrical part of HKL’s procurement of new trams in 2009. At that time, HCT used Variotram type trams, which were difficult to operate in Helsinki. Preparations were started for the procurement of new trams, which were to eliminate the known shortcomings of the existing trams and significantly simplify the operation. The knowledge and experience of our and other participating companies and HCT employees in modernizing and operating trams were of great help. It was established that the new fully low-floor tram must have through-going wheel axles and freely rotating bogies that had proven their durability and suitability in Helsinki for decades. In order to keep the floor of the tram above the bogies low, the traction motors and brakes had to be placed on the sides of the bogie and the joints connecting the wagons had to be moved aside. The diameter of the wheels was also reduced. In order for even short tram wagons with only one bogie to have a reversible bogie, an original solution was devised in the HCT (patent FI124938B Rail Vehicle). The technical requirements for the electrical part of the new tram were partly based on the specification of the intermediate part of the MLNRV II tram, taking into account the possibilities of modern technology. Based on the same specification, Transtech OY manufactured for HCT Artic type trams, which have proved to be a very successful tram model. Škoda bought Transtech in 2015 and produces similar trams under different names.

39. Modernization of the lathe management of the NRV wheel profiles of HCT trams – 2009. The wheel profiles of NRV type I and II trams had to be turned twice a year. The lathe used at that time did not turn the tram wheels around during turning. Tram traction motors were used for this purpose, which were connected to an external power supply by means of a separate plug. There were many problems with the sockets under the tram, so it was recommended to use the tram’s own drive to control the motors while turning. This required changes to the tram traction drives and the addition of an additional control panel to the lathe so that the operator could properly adjust the speed of the undercarriage wheels at his workplace.

40. Design and manufacture of tram MLNRV II heating controllers – 2008 – 2009. In order to control the heating equipment of the low-floor intermediate part attached to the tram, a specially designed heating controller HC24 and a series of sensors had to be developed. Later, air conditioners were added to the intermediate parts and the heating controllers were also modernized.

41. HCT Passenger Counting System Dilax Implementation Project for MLNRV I and MLNRV II Trams – 2008. In order to optimize the schedules of tram lines, HCT requested information over data communication on how different trams are used by passengers. To do this, sensors and a central counting device had to be added to each door of the tram. The design and commissioning of the passenger counting system was our task in cooperation with Dilax.

42. Development of the automatic sound level adjustment device for the sound amplifier Vehtec of tram NR II. The automatic reporting of stop names did not take into account the noise level on the tram. As a result, the acoustic announcements of the tram full of passengers in the middle of the city noise were too quiet and startlingly loud for people at quiet terminals. HSL commissioned us to develop a volume control that takes into account the noise level of the cabin. The device worked very well, but was not widely used, because the acoustic messages of the stop names were given up due to the information boards.

43. Compilation of the spring braking device manual for HCT trams GT6 and GT8 – 2008. The low-floor intermediate sections of GT 8 trams used RACO’s electromechanical release spring brake GBM V-08 MA with control unit 6GQ9 101 (Siemens) with microprocessor control. The reference value was calculated from the signals of the brake current sensor and the wagon weight sensor. The device was quite complicated, included an ABS system, etc. There was partial information from several different sources in German. We have compiled a complete user guide in Finnish.

44. Design and manufacture of new HCT-style dashboards for HCT trams GT6 and GT8 – 2007. In 2005, HCT purchased 11 GT6 and GT8 trams (Düvag) from Mannheim, Germany, to cope with the increased capacity of the World Athletics Championships. 10 of them were equipped with HKL equipment and the new HCT-style dashboards we produced, one GT8 was left in its original form.

45. Production of MLNRV 18 uH commutation chokes for HKL trams – 2007. NRV I and NRV II used forced commutation thyristor converters in DC traction drives. Over time, the switching chokes had experienced insulation surges and other failures, so they were no longer sufficient. Spare parts could no longer be ordered as production was discontinued and the company that produced them was sold. We produced new chokes, which are still in use.

46. Maintenance contract for static auxiliary power converters and traction drives for Tallinn Tram Park trams – 2007. TTTK AS, in cooperation with Tallinn University of Technology, had produced traction converters and battery chargers for KT4SU type trams. These converters required periodic maintenance, such as air filter replacement, cleaning, and so on.

47. Modernization of tram speed sensors – on all MLNRV I and MLNRV II type trams from 2006 to 2015. NRV type tram speed sensors used obsolete type single channel inductive sensors, which occasionally gave speed errors. The sensors were replaced with modern permanent magnet Hall encoders. To do this, the encoder wheel also had to be replaced. The speed measurement errors caused by the sensors no longer occur and the trams then work very reliably.

48. Advising VIS (Verkehrs Industrie Systeme GmbH) in Germany on the production of electrical components for intermediate parts of MLNRV I and MLNRV II for HCT trams – 2009. HCT procured the production of 52 low-floor tram intermediate parts from Verkehrs Industrie Systeme GmbH in Germany. Since the electrical part of the intermediate parts was designed by us, we built the electrical equipment of the prototype of the intermediate part and compiled their test instructions, then consulting was also ordered from us.

49. Compilation of testing instructions for the electrical part of the MLNRV I and MLNRV II intermediate parts for HKL trams – 2009. The electrical part for adding intermediate parts was designed by us and we also built the electrical equipment for the prototype of the intermediate part. However, as an international procurement was carried out for the production of intermediate parts, a testing manual was also required to identify possible defects, which was ordered from us.

50. Electrical design, prototype construction, testing and handover of HCT tram NR II low – floor intermediate sections in accordance with Bostrab standards in 2006.

51. Compilation of MLNRV I and MLNRV II electrical overhaul instructions for HCT trams in 2005. Previously, HCT had made significant updates to the overhaul of the mechanical part of these trams and the corresponding instructions, but the electrical part was not covered by the instructions.

52. Advising HKL on feasibility study, calculations, modeling to add low-floor intermediate sections for NR II (Valmet) trams and NRV II traction modernization project to increase capacity when adding an intermediate section – 2005. To ensure free movement of people with reduced mobility, HKL had procured new low-floor trams with frequent technical problems. Therefore, the possibility of adding low-floor intermediate sections to existing high-floor NRV (Valmet) trams was considered. The additional wagon would increase the weight of the tram, which could cause problems in keeping to the timetable and be dangerous to traffic due to the extension of the braking distance. In order to solve these problems at the outset, the reserve for increasing the power of the tram traction unit had to be studied and the need for additional braking systems for the additional wagon had to be modeled on a computer.

53. HCT equipment installation project for GT 6 and GT 8 trams and study of heating equipment and thermal insulation – 2005. In 2005, HKL purchased 11 GT6 and GT8 trams (Düvag) from Mannheim, Germany, to cope with the largest passenger capacity of the World Athletics Championships. Before being allowed to carry passengers, they had to reorganize their equipment and install HCT equipment. It was our job to design the changes. The control of lights and interior lighting, the control of the dashboard, the mirrors and the windscreen washer, as well as the turn control system had to be changed. A new dashboard was designed according to HCT’s wishes. The project solved the integration of sound amplifier, stop information system, information boards, radio transceiver, ticketing device, validators, etc. into tram systems. A separate study was conducted on the GT6 and GT8 heating system and thermal insulation to determine their properties and suitability for use in Helsinki winter conditions.

54. Investigation of the causes of power thyristor failures of TTTK AS trolleybuses Škoda 14Tr – 2005. Based on statistical data, the causes of power thyristor block insulation flash-overs and short circuits, control electronics and cooling system failures were found in these trolleybuses. The operating modes of the thyristors were checked by calculations and measurements. Solutions were proposed to eliminate the causes of the problems found in trolleybuses and the workshop, and suggestions were made to supplement the repair instructions for the traction converter.

55. Development of static IGBT battery charger inverters for TTTK AS Tallinn tram park in 2002. At that time, the main KT4SU type trams in Tallinn used a motor generator as a 24 V auxiliary power source. There were many problems with the motor generator, in addition to which it no longer had enough power to power the electrical equipment in the low-floor intermediate sections. As we had successfully designed and manufactured IGBT traction converters for the same trams, we also received an order for the development and production of static voltage converters. The converters had 24 V 200 A DC and 3 x 400 V 50 Hz 2.5 kVA AC output.

56. Advising TTTK AS on the tram fleet and MGB (Mittenwalden Gerätebau GmbH) (with Stadler winding technology) for the addition of low-floor intermediate sections to KT4SU trams with innovative IGBT traction – 2000; testing, delivery in 2002 As we spoke German and had full knowledge of the innovative IGBT traction we designed and how it could handle the extra weight of an additional low-floor wagon and integrate it with tram systems, we were commissioned to advise on the addition of the intermediate section and to receive the low-bottom section in Germany. We translated the technical texts of a number of intermediate sections into Estonian and compiled the instructions for the low-floor intermediate section of the extended tram.

57. In cooperation with Tallinn University of Technology, development, testing and production of IGBT traction converters for trams KT 4 in Tallinn Tram Park (based on Jüri Joller’s doctoral thesis). There were 30 of them in use during 15 years, 12 of them with low-floor intermediate parts – in 2000 – 2004. In 2021, the last such tram No. 104 will still be operational.

58. Series of patents based on Jüri Joller’s doctoral thesis:
EE04909B1 · Power exchange control system for vehicles connected to the supply line EE00332U1 · Electric vehicle traction converter
EE05445B1 Electric vehicle traction unit
EE00331U1 High frequency auxiliary power supply for electric vehicles

59. Jüri Joller’s doctoral thesis “Research and development of energy-efficient traction drives for trams” Tallinn University of Technology, 2001. The doctoral thesis dealt with the problems of tram traction drives. The classification of tram drives and their control methods and the theoretical approach to energy analysis are presented. The tram energy balance equations and the energy flow diagram have been compiled on the basis of the energy analysis of the drive system structure, theoretical research and real measurement results. The possibilities of energy saving of Tallinn trams have been identified in the work. To this end, computer models of the traction unit have been developed and compared with actual measurements. The most important practical part of the doctoral thesis is the development of a 160 kW energy-efficient tram drive for the Tallinn Tram and Trolley Bus Co with an original circuit solution. The drive converter based on the latest power transistor modules can be used for both DC and AC drives with few modifications. The use of super-capacitor energy storages in tram drives was also proposed, which was practically not implemented due to lack of money, but was protected by patents.