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Students at TU Vienna rely on the blueglobe TRI from PFLITSCH in their racing car project

Students at TU Vienna rely on the blueglobe TRI from PFLITSCH in their racing car project
Motor racing is a prime example of situations where good screening attenuation is a crucial criterion in the choice of cable gland. The electronics built into the vehicle are very sensitive to electromagnetic interference and must be protected against it. It was for this reason that the Vienna University of Technology (TU Vienna or TUW) students decided they needed the blueglobe TRI from PFLITSCH.
In this article, you can read about their project and where they use PFLITSCH’s cable glands:

As the TU Vienna’s official Formula Student Team, we take part in the worldwide Formula Student races in a car we designed and developed ourselves. The special point about this series of races is the car constructor competition, which only 100% student teams can enter. The students are all studying for bachelor’s or master’s degrees or taking equivalent courses. In addition to traditional dynamic disciplines such as acceleration, ski pad, autocross or endurance competitions that the car has to enter, the team is also judged on the design and engineering of its vehicle and their presentation of its estimated manufacturing costs.
 
Our vehicle this year is a 300 cm long, 150 cm wide and 120 cm high electric racing car with a wheelbase of 157 cm. The vehicle we designed only weighs a very creditable 170 kg, a feat which is made possible by using mainly carbon-fibre for the monocoque, aerodynamics pack, wheels and even parts of the suspension system. The whole thing is propelled by two permanent magnet synchronous motors, which deliver a torque of 780 Nm through an intermediate gearbox. Each of the motors has a peak output of over 40 kW and rotates at up to 18,000 rpm, which allows the vehicle to reach a top speed of about 140 km/h. This speed is more than enough for the disciplines in Formula Student. The associated power electronics for this season’s car is a team-designed inverter with two IGBT power modules, which work at 530 V and handle peak currents of up to 130 A. The energy is supplied from a self-built lithium polymer rechargeable battery unit, which consists of 126 cells in series, each of which in turn consists of 2 cells in parallel, to produce a design voltage of 529.2 V and a capacity of 3.7 kW. To provide data for various traction control and vehicle dynamics regulating systems as well as information about the condition of other parts of the vehicle, it has a host of sensors to measure, among other things, acceleration, various temperatures, the rotation speed of each wheel, shock absorber travel, battery cell voltages and much more. This and other electrical units, such as the engine control unit (ECU), battery management system, inverter and the Raspberry Pi for the display, communicate over two CAN 2.0 data buses.
 
PFLITSCH supported us in our project with cable glands from the blueglobe TRI series. The drive-train’s high voltage and its current requirement combined with the high 18 kHz switching frequency of the inverter creates high EMC loads, which would interfere greatly with the two CAN buses. To keep these EMC loads as low as possible, all the cables that carry voltages greater than 60 V are fitted with a cable screen as specified in the regulations to attenuate this effect. An insulation monitor measures the resistance between the wires in the cable and its screen to detect any damage to the cable as quickly as possible. There are many cable penetrations and threaded connections with contacts for a cable screen. However, our vehicle is a prototype. Therefore, we expect and require cables to be removed and reinstalled many times quickly and easily without causing damage to the cable screen. With similar alternative products to the blueglobe TRI, this is possible only with difficulty and in some cases not at all. The cable gland is made completely out of stainless steel, which simplifies our job of connecting this to the vehicle’s ground potential, because the cable glands are fastened onto the housings, which consist of several layers of carbon- or glass-fibre into which a layer of fine copper braid is laminated.
 
The cable glands are also able to resist the high mechanical loads associated with the vehicle. As can be seen in the photograph, the motors sit outside the monocoque and are attached directly to the wheel supports. The cables to the motors are subjected to strong vibrations and acceleration forces caused by the uneven running surfaces and high speeds around bends. The excellent strain relief of the blueglobe TRI is indispensable here and essential on safety grounds, because the voltages in the cables are well over the level that would be fatal to humans and the rules state that every cable must be able to resist a minimum tension of 200 N at every penetration. The IP 68 ingress protection rating is also an advantage because we do not always race in dry conditions.
 
Our team consists only of students, all volunteers who work without pay on our racing car. We are completely dependent on the kind support provided by our sponsoring companies and organisations. With this very much in mind, the TU Vienna Racing Team would like to express its thanks again to PFLITSCH for the provision of several blue globe TRI cable glands.
 

 

 

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