Transporte ferroviario
Durante la explotación del material rodante, se imponen requisitos muy estrictos a la operatividad y continuidad del suministro de energía de la batería de tracción. También es necesario garantizar la plena funcionalidad de los elementos estacionarios alrededor de la vía férrea. Todo esto es posible gracias a una serie de dispositivos de supervisión del aislamiento (IMD) de HIG fabricados por la empresa HAKEL.
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Mobile part – Traction batteryTraction battery is an essential element of all rolling stock vehicles. The safety, communication and the most critical vehicle control technology are supplied from the DC voltage of the traction battery. Due to this, very high requirements are placed on the operability and continuity of power supply from the traction battery.
The standard solution to prevent unexpected power supply outages from the traction battery is to operate this power supply system as isolated from the vehicle chassis. Any emerging insulation breakthrough on the vehicle chassis should be monitored and signalled to the vehicle control unit (VCU) well in advance before the insulation breakthrough may cause a short circuit in the power supply.
HAKEL company has developed a range of HIG*VDC/T products for traction battery monitoring. These are insulation monitoring devices that meet the requirements of EN 50155 and IEC 61557-8 standards. An interesting feature of these IMDs is that they monitor the insulation resistance in both (the positive and also negative) branches of the IT power supply system. Such IMDs therefore provide two separate values of the two insulation resistances. This is especially useful when looking for an insulation breakthrough, where the service team can inspect only the specific half of the traction battery voltage distribution.
We distinguish two basic product lines, namely HIG*VDC/T and HIG*VDC-L/T. These two series differ in the measured range of the insulation resistance. HIG*VDC/T product line monitors the insulation resistance in the range of 5 to 990 kΩ, meanwhile HIG*VDC-L/T product line monitors the insulation resistance in the range of 2 to 550 kΩ. If the measured resistance value is lower than the measured range “
HIG*VDC/T devices are intended to monitor 12, 24, 48, 72 and 110 V DC voltage, are powered from the measured system and communication with VCU is possible by using RS485 bus or relay outputs. Devices meet OT3 temperature class (according to EN 50155). If higher temperature class is required, IMD type HIG99 can be used. HIG99 meets OT4 temperature class and allows communication with VCU via CAN bus.
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Mobile part – Traction container and drive unitsTraction container is a device that usually contains a galvanically isolated unit of a multi-quadrant power converter, which serves to regulate the traction motors of the electric traction vehicle. Usually, the traction container contains one power inverter, which drives one or two traction motors.
Due to higher safety and reduction of EMC/EMI interferences, each traction container is designed as an isolated system, galvanically separated from the vehicle chassis as well as from the input voltage. From the design point of view, an isolated system is created by a high-frequency isolating transformer, followed by a multi-quadrant rectifier, which creates a DC intermediate circuit, and the inverter itself, which supplies the required AC voltage and variable frequency for the traction asynchronous/synchronous motor. The isolated system of the drive unit is therefore in most cases a combined AC/DC isolated system. That is, a system that contains a galvanically connected alternating and direct current sides and insulation fault may occur on both sides.
In these cases, AC/DC type insulation monitoring devices are used to monitor the insulation. These devices are able to detect insulation breakthroughs both on the AC side (i.e., motor side) and on the DC side (i.e., inverter intermediate circuit side).
HAKEL company uses the HIG99 insulation monitoring device for these purposes. These are IMDs that meet the requirements of EN 50155 and IEC 61557-8 standard. The measured range of insulation resistance of HIG99 is 1 kΩ to 10 MΩ and the device is powered by 24 V DC independent low voltage. From the point of view of the measured system, the maximum voltage is 1 000 V DC / 710 V AC (10 to 440 Hz). If monitoring of higher IT system voltage is required, it is necessary to use a HIG-CD 1k8 coupling unit, which allows up to twice the voltage of the measured system. HIG99 device allows to inform about the insulation status via signalling relay or HIG99 KM CAN communication module can be used for direct connection to the CAN bus with the CAN OPEN protocol.
In terms of installation location of IMDs, we recommend selecting the place where the insulation status fault is most likely to occur. In the case of the traction container, it is the AC side, because the most common cause of insulation fault in the drive unit is usually the traction motor insulation disruption.
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Mobile part – Central power source, auxiliary drives and passenger compartmentModern cars, not only for railway, usually generate a voltage of 3× 400 V / 50 Hz from the heating coupling distribution. This industry standard allows vehicle manufacturers to use common industrial components, for example, frequency converters for ventilation system drives.
3× 400 V / 50 Hz supply system is usually created by the so-called central power source. It is a high-frequency transformer, rectifier, DC intermediate circuit and inverter with a fixed frequency of 50 Hz. However, it is also possible to come across different approaches (e.g., low-frequency isolating transformer at the inverter’s output). Such formed three-phase system is left as galvanically isolated, both from the input voltage and the vehicle chassis. It is therefore an IT type power supply system. Great advantage of this approach is safety of passengers who are allowed to power their own appliances from this system, through the 230 V socket.
In order to ensure that the power supply system is actually separated from the vehicle chassis, the insulation monitoring devices are used. Such devices must notify any emerging insulation breakthrough in advance, before the insulation resistance of the IT power supply system drops below the critical limit.
HIG99 is the recommended type of an insulation monitoring device. It’s the AC/DC type, thus it is able to detect insulation fault even in direct current sides of the central power source. This device can be connected to the train control system via CAN bus, when HIG99 KM CAN communication module is used. Then the IMD provides service information about the current level of the insulation resistance.
Another HIG99 advantage is the possibility to use the function of remote unblocking (disconnection) of the device from the measured system. This is used in cases where it is possible to connect more train cars (every car has its own central power source) and thus create one galvanically interconnected 3× 400 V / 50 Hz system throughout the whole trainset, where CES work in parallel, or some may be completely turned off. Only one insulation monitoring device must remain active in such cases, other devices must be disconnected from the power supply system. IMD is an active device whose presence affects the measured IT power supply system and mutual operation of multiple insulation monitoring devices within one IT power supply system is excluded because of unwanted measurement interferences. HIG99 can be unblocked by a command via CAN bus or by a logic input.
It is possible to use HIG93T insulation monitoring devices if it is not required to monitor the status of central power source DC part. HIG93T in cooperation with TL 400T coupling device also enables monitoring of the 3× 400 V / 50 Hz system.
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Stacionární část – Zabezpečovací a sdělovací technikaŽelezniční infrastruktura je z velké části vystavěna na izolovaných soustavách. IT sítě lze najít jak v napájecích trakčních měnírnách, tak v zabezpečovací technice u přejezdů a návěstidel. Lze se s nimi setkat jak na traťových, tak staničních zabezpečovacích a sdělovacích systémech.
Napěťové poměry v těchto IT sítích jsou různé, setkáváme se sítěmi malého DC napětí pro záložní akumulátory, ale také s rozvodem 3× 6 000 V pro napájení netrakčních spotřeb podél širé trati. Z toho plyne nutnost řešit každou aplikaci individuálně. Firma HAKEL má pro tyto účely vyvinutou celou řadu výrobků hlídačů izolačního stavu.
Pro AC soustavy s nominálním napětím do 230 V AC doporučujeme hlídač izolačního stavu HIG93. Tento hlídač je navržen tak, aby monitoroval izolační odpor v rozsahu 5 až 900 kΩ a je napájen nezávisle na měřené soustavě. To znamená, že hlídač je schopen změřit stav izolace IT sítě i v jejím beznapěťovém stavu. Toho se typicky využívá právě u kritické infrastruktury jako je zabezpečovací technika, kdy je nutné bezporuchový stav izolace znát ještě před zapnutím samotného systému.
Pokud je měřící rozsah nevyhovující, lze využít hlídače řady HIG94, které mají měřící rozsah od 200 kΩ do 5 MΩ, nebo naopak řadu HIG93/L, která je určena pro nízké izolační stavy, tj. od 0,1 do 90 kΩ.
Pokud je potřeba monitorovat napětí vyšší než 230 V, je zákazníkovi k dispozici řada přizpůsobovacích členů TL*. Tyto přizpůsobovací tlumivky umožňují připojit hlídače z řady HIG93 a HIG94 k napětím vyšším, typicky 3× 400 V, 3× 500 V, až do napětí 3× 6 000 V.
Pro stejnosměrné sítě, zabezpečovací a sdělovací techniku, jsou určeny hlídače řady HIG*VDC pro rozvody 12, 24, 48, 72 a 110 V DC. Měřící rozsahy této řady jsou vždy 5 až 990 kΩ, případně 2 až 550 kΩ pro řadu HIG*VDC-L.
Všechny hlídače (AC i DC) jsou standardně vybaveny displejem pro obsluhu a nastavování, dále pak sběrnicí RS485 pro vyčítání měřených veličin, a reléovými výstupy pro logickou informaci o stavu izolačního odporu.
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Stationary part – Heating of switchesIn order to be able to operate the railway traffic safely even in the winter months, it is necessary to deal with the formation of icing and snow layer between the switch blades. If the icing is not removed, there is a risk that the rail switch blade will not settle to proper position. This would not endanger security itself, but it would lead to a restriction in traffic. To prevent this, switches are equipped with switch heaters. These usually automatically detect icing in the winter months (or at least low temperature and humidity) and in the case of electric heaters of switches removes icing by using resistance heater elements.
There are two ways to power an electric heater. It is either a supply from a non-traction line (typically 3× 6 000 V / 50 Hz) or a supply from the overhead line (typically 25 kV / 50 Hz or 3 kV DC). In both cases, the voltage is too high to be safely used to power the heating elements. For this reason, electric heaters with reducing, isolating transformers / galvanically isolated converters are installed in the rail track.
Because the heating elements are installed directly in the track, a great mechanical stress and insulation degradation occurs here. Therefore, there is a risk of a conductive connection between the heating system and the rail and thus the formation of a dangerous touch voltage. This risk can be monitored well in advance using an insulation monitoring device.
Electric heaters’ output voltage is usually single-phase 230 V / 50 Hz. We recommend using devices of HIG93T series, if the source is a normal transformer. These devices are certified up to operating temperatures of -25 °C. If the customer requires a higher temperature range, or wants to monitor the DC side of an inverter, HIG99 device type can be used, which is certified up to -40 °C.
Both of these types of insulation monitoring devices have two fault levels and two output relays. Thanks to this, it is possible to signal at one output relay an information about reduced, but yet faultless insulation resistance. At the second relay it is then possible to signal the fault insulation status. This relay can then, when a fault is detected, disconnect the heating source from the heating elements and bring the electric heater to a safe condition. All this information can be signalled to the control room both by signalling relays and by RS485 bus.Nahrávám ...
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